Updated on 2022/08/17

写真a

 
UKAI, Masanari
 
Affiliation
Faculty of Science and Engineering, School of Creative Science and Engineering
Job title
Assistant Professor(non-tenure-track)
 

Papers

  • BUILDING WELLNESS PERFORMANCE AND WORK ENGAGEMENT

    Masanari UKAI, Yuto CHIMOTO, Takuya MURAKAMI, Yuya SUZUKI, Shin-ichi TANABE

    Journal of Environmental Engineering (Transactions of AIJ)   86 ( 781 ) 271 - 278  2021.03  [Refereed]

    DOI

  • Required temperature distribution based on clothing insulation and metabolic rate survey in Japan

    Masanari Ukai, Tatsuo Nobe

    Indoor and Built Environment   29 ( 6 ) 775 - 782  2020.07

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    In this study, the authors evaluated clothing insulation and changes in the metabolic rate of individuals in an office environment to determine thermal comfort. Clothing was evaluated using a questionnaire completed by 1306 workers in nine offices. The metabolic rates of 86 workers in three offices were measured using a physical activity meter. The distribution of the temperature at which a person in the room perceived a neutral thermal sensation was then calculated from the determined metabolic rates and clothing insulation values. The results demonstrate a noticeable difference between the average and most frequent values during the summer. Moreover, the required temperature distribution is not normal; rather, it is broad and skewed to the low-temperature side. Therefore, even if a thermally uniform environment is provided at the average required temperature by preventing temporal and spatial variations in the thermal environment, complaints of an unacceptably hot thermal environment are more likely to occur than complaints of an excessively cold thermal environment.

    DOI

  • Study on Cool Chair equipped with warming function

    Jun Koyama, Yusuke Doi, Masanari Ukai, Tatsuo Nobe

    E3S Web of Conferences   111  2019.08

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    Recent air-conditioning systems aim to provide thermal comfort for an unspecified number of residents. However, office workers may perceive the feeling of comfort differently depending on their clothing, metabolic rate, and personal activity level. This may cause difficulties in maintaining an optimal thermal environment. To address this problem, personal air-conditioning has attracted attention, which is highly versatile and can reduce thermal discomfort and provide comfort to all office workers by enabling individual thermal control. Therefore, the authors focused on developing an office chair, the “Cool Chair”, as a chair-type personal air-conditioning system with a cooling function from 2003 to 2016. The authors then added a warming function for year-round operation, creating the “Cool Chair with Warming Function” in 2017. Subjective evaluation results are reported. These experiments using the new chair indicated that the warming function achieves steady state in 30 minutes and the equivalent temperature of the entire body increases by +2°C. In subject experiments, the warming and cooling functions were adjusted according to individual preferences, and the cooling function was used even during winter by some individuals. The authors also confirmed that the feeling of comfort by the subjects improved at both 19°C and 22°C.

    DOI

  • Human-oriented design of an indoor thermal environment

    Masanari Ukai, Tatsuo Nobe

    E3S Web of Conferences   111  2019.08

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    In this study, an initial survey of clothing insulation and changes in the metabolic rate of individuals in office spaces was performed to establish the distribution of room temperatures at which individuals perceived a neutral thermal sensation. Subsequently, the indoor thermal environment in four offices was surveyed during the summer with different air-conditioning systems to determine the thermal environment stability in each case. The results revealed that for the required temperature, there was a noticeable difference between the average and most frequent values. Moreover, it was determined that the required temperature distribution is not normal, but rather, it is skewed to the low-temperature side. In addition, the radiant air-conditioning system was found to generate a narrow distribution of the equivalent temperature and hence, facilitated a more uniform thermal environment compared to a convective (multi-unit) air-conditioning system. Therefore, in buildings with convective air-conditioning systems, even if the planar average thermal environment is categorized as comfortable, it may be possible that workers who are sensitive to the cold or heat will complain of discomfort more frequently than those in buildings with radiant air-conditioning systems because the probability of workers sitting in cold- or hot-spot areas is higher in the former case.

    DOI

  • Field study of thermal environment acceptability using ostracon voting device

    Masanari Ukai, Yuta Ichikawa, Tatsuo Nobe

    Proceedings - Windsor Conference 2014: Counting the Cost of Comfort in a Changing World     668 - 677  2019

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    This study aims to assess the thermal conditions of an indoor environment deemed unacceptable by workers. For this purpose, Ostracon, a voting device, was developed to record the physical environment at the time a worker presses a button to express a complaint. Ostracon was used to record the opinions of 90 workers about their thermal environment in six offices during the summer. The results show that workers found the indoor thermal environment unacceptable even when the static thermal conditions were within a range that was predicted to be comfortable. Moreover, most of the workers' complaints were expressed moments after returning from tasks performed outside the office. This suggests that the workers' complaints were influenced by factors other than the indoor environment such as thermal history.

  • Development and evaluation of chair-mounted isothermal airflow generator cool chair 2016

    Masanari Ukai, Gaku Tateyama, Yusuke Doi, Jun Koyama, Tatsuo Nobe

    ECOS 2018 - Proceedings of the 31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems    2018

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    In an office space, each office worker has his or her own preference for thermal environmental conditions and personal thermal comfort. Recently, as a solution to such problems, personal air-conditioning systems have attracted much attention to improve the thermal comfort of office workers. Using a personal air-conditioning system, each worker can adjust the thermal environment to his or her desired preference. To create a personal air-conditioning system, the authors enhance an office chair using an airflow generator that has an environment adjustment function. This chair, called a “cool chair,” has been under development since 2003. In this study, the authors develop a new model called cool chair 2016 where thermal environmental selection range is improved. In a physical performance test using a thermal manikin, the equivalent temperature of the entire body was noticeably lower than that of a user seated in a normal office chair. Moreover, the results of a trial test by workers in an office show that workers who used the cool chair felt more comfortable.

  • Operational status evaluation of integrated hybrid VRF system

    Atsushi Hashimoto, Masanari Ukai, Yuma Furuhashi, Ken Yasuda, Tatsuo Nobe

    ECOS 2018 - Proceedings of the 31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems    2018

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    Variable refrigerant flow (VRF) systems are used as air conditioning systems in small and medium-sized buildings in Japan. Conventionally, the two most popular types of VRF systems are the Electrical Motor-Driven VRF system (EHP) and the Gas Engine Driven VRF system (GHP). However, in recent years, society has been increasingly demanding energy saving and the best energy mix. This required an air conditioning system that is capable of flexibly using energy according to the application and situation. Consequently, a hybrid air conditioning system (called the Integrated Hybrid VRF system) that satisfies this need was developed. The developed system enables operation in accordance with energy prices and usage situations by connecting a GHP and an EHP in a single refrigerant cycle. Subsequently, in recent years, the Integrated Hybrid VRF system has been utilized in small and medium-sized buildings. However, the actual performance characteristics of this system have not yet been investigated. In this study, measurements were obtained during the actual operation of an Integrated Hybrid VRF system operating in an office building and controlled by a remote monitoring server to enable optimal operation according to the application and situation. In this report, the actual operational status of the Integrated Hybrid VRF system with optimal operational control is presented.

  • Dynamic evaluation method for indoor thermal environmental acceptability using P-R chart

    Masanari Ukai, Tatsuo Nobe

    Proceedings of 10th Windsor Conference: Rethinking Comfort     161 - 175  2018

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    This study was conducted to characterise thermal environmental acceptability for various air-conditioning systems. The authors developed a new thermal comfort index called a P-R chart using the concepts of "provided temperature" and "required temperature" for use in evaluating uniform, high-quality indoor thermal environments and non-uniform, unsteady thermal environments. In this study, first, the authors surveyed the required temperature distribution of workers. Then they surveyed indoor thermal environmental stabilities in the four offices during the summer with different air-conditioning systems to calculate provided temperature distribution. Finally, the indoor thermal acceptability in offices was evaluated using the P-R chart. The results showed that the convective air-conditioning systems caused wide temporal and spatial variations in the thermal environment. Therefore, in buildings with convective air-conditioning systems, even if the planar average thermal environment is categorised as comfortable, it is presumed that workers sensitive to cold or heat will complain of discomfort more frequently than those in buildings with radiant air-conditioning systems and floor-supply displacement HVAC systems, because the probability of workers sitting in cold- or hot-spot areas is higher in the former case.

  • Measurement survey on thermal and acoustic environment in natural ventilating office building

    Gaku Tateyama, Masanari Ukai, Hiroshi Muramatsu, Tatsuo Nobe

    Healthy Buildings Europe 2017    2017

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    The authors investigated an office building in Japan incorporating energy-saving features and environmental technology. The building is medium-sized and incorporates two air-conditioning systems: a natural ventilation system and radiation air-conditioning system. The temperature environment of the building and its psychological effects on office workers were surveyed using a questionnaire. The measurements of the natural ventilation system were made in 2016. The natural ventilation system of this building reduces the indoor temperature by first opening the window. The ceiling uses the heat storage capacity of concrete to retain a low temperature in the room during the night. Air flows through the room with the natural ventilation system. Further, various problems occur because of noise, and the building has a constantly fluctuating environment. However, according to the results, even in such a natural ventilation system in which the indoor environment changes, office workers are able to conduct business without much dissatisfaction.

  • Simplified on-site performance evaluation method for VRF systems

    Yasuhiro Sugata, Mitsuhide Yasuda, Masanari Ukai, Tatsuo Nobe

    Healthy Buildings Europe 2017    2017

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    Few case studies have examined the actual operation of variable refrigerant flow systems. The installation conditions for each case, such as the number of indoor units connected, piping length, height difference, and refrigerant filling budget, are not fixed. Therefore, accurately grasping the changes in performance is difficult. Moreover, specifying the performance evaluation method is necessary because of the complex and diverse operating conditions for each case. The system performance intended by the air conditioning designer/builder is not attained because the actual driving situation differs for each property. Therefore, possible complaints of the system being “too hot” or “too cold” raise a concern.

  • Thermal comfort investigation of air-conditioning system with variable airflow in office

    Takuya Wakao, Masanari Ukai, Tatsuo Nobe

    Healthy Buildings Europe 2017    2017

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    This work clarified the effectiveness and comfort of an air-conditioning system with variable airflow by measurement and questionnaire survey. This air-conditioning system can create horizontal and vertical airflows by a special air outlet. In addition, this system can adjust air volume. Thus, with this system, one can make choices in line with one's airflow preferences, within different air-conditioning zones. Airflow can be set using a five-stage mode, through a user interface that is installed in the room. The measurement results confirmed that air speed difference was attached to each thermal sensation setting, and air volume adjustment functioned effectively. The questionnaire results confirmed that over 90% of officer workers are somewhat comfortable and that the air-conditioning system is extremely comfortable.

  • Comparison between thermal environmental stabilities of radiant and convective air-conditioning systems

    Masanari Ukai, Tatsuo Nobe

    Healthy Buildings Europe 2017    2017

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    Radiant air-conditioning systems and floor-supply displacement heating, ventilation, and air conditioning (HVAC) systems have recently attracted considerable attention. However, such systems have not yet seen widespread use because the degree to which they increase thermal comfort is not clear. In this study, the authors measured the planar thermal deviation during summer in four offices: two offices employed a radiant air-conditioning system and a floor-supply displacement HVAC system, and the other two offices employed convective air-conditioning systems. The results showed that the convective air-conditioning system caused wide temporal and spatial variations in the thermal environment. Therefore, in buildings with convective air-conditioning systems, even if the planar average thermal environment was categorized as comfortable, it was presumed that workers who were sensitive to cold or heat complained of discomfort more often than those in buildings with radiant air-conditioning systems because the probability of workers sitting in cold or hot spots increased.

  • Study on the energy-saving system which using renewable energy for Earth Building TACHIKAWA Part 3 . The Measurement of Thermal Environment and Questionnaire on Comfort in fall

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2016   273 - 276  2016

    DOI CiNii

  • Study on Probabilistic Thermal Acceptability Evaluation (Part4) Application of P-R chart to Offices in Summer

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2016   185 - 188  2016

    DOI CiNii

  • Self-stabilizing urban ZEB with high thermal capacity to store renewable energy:Part1.Introduction system and outline of the building

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2016   305 - 308  2016

    DOI CiNii

  • Part 2. Thermal environment evaluation Self-stabilizing urban ZEB with high thermal capacity to store renewable energy

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2016   309 - 312  2016

    DOI CiNii

  • 都市における自然エネルギーと躯体熱容量を活用した自律安定型ZEBに関する研究 (第3報)計算モデルによる吸着式冷凍システムの運用法検討

    富樫 英介, 村松 宏, 舘山 岳, 矢田 達也, 鵜飼 真成, 野部 達夫

    空気調和・衛生工学会大会 学術講演論文集   2016   313 - 316  2016

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    <p>研究対象施設にはマイクロコジェネレーションシステムを用いた冷温水供給系統と空気熱源ヒートポンプによる冷温水供給系統がある。両系統の同時起動が不要な低負荷時に、いずれの系統を優先的に起動すべきかは、外界条件や電力およびガス料金などに依存する。本報では簡単なエネルギーフローモデルを作成し、マイクロコジェネレーションシステムと空気熱源ヒートポンプの起動判定を行う方法を示す。</p>

    DOI CiNii

  • Study on Acceptability in Thermal Environment(Part4)Influence of Attribute of Office Worker on Acceptability in Thermal Environment

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2014   149 - 152  2016

    DOI CiNii

  • Field Study of Thermal Environment Acceptability in Offices Using Ostracon

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2014   13 - 16  2016

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  • Study on Acceptability in Thermal Environment (Part3) Field Study on Unacceptable of Indoor Thermal Environment in Middle Season

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2014   145 - 148  2016

    DOI CiNii

  • Study on the Air-Conditioning System Corresponding to ZEB

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2014   117 - 120  2016

    DOI CiNii

  • Study on the Air-Conditioning System Corresponding to ZEB (Part 1)Outline of the Air-Conditioning System, and the Experimental Result of Ambient Air-Conditioning

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2014   113 - 116  2016

    DOI CiNii

  • ZEBを目指した都市型超高層オフィスビルの研究 (第13報)夏期におけるアンケート調査と受容度申告

    橋本 祐, 伊藤 清, 高 博也, 鵜飼 真成, 高橋 満博, 野部 達夫

    空気調和・衛生工学会大会 学術講演論文集   2014   189 - 192  2016

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    <p>S社本社における執務者の快適性の把握を目的とし,2012年,2013年に実施された夏期アンケート調査,本年度夏期に実施されたオストラコンによる受容度申告調査について報告する。結果として2013年のアンケート調査にあたり,室内設定温湿度が2012年の調査時から変更があったため各項目における回答の変化が認められた。オストラコン調査では温冷感申告,受容申告は快適範囲内外に見られたが,受容申告「受け入れられる」の申告は快適範囲外における申告割合の方が多い結果となった。</p>

    DOI CiNii

  • Research on the Verification of the Component Engineering and its Optimization for Smart Building Construction (Part 2) Study of Gas Consumption of the Waste Heat Recovery Absorption Hot and Chilled Water Generator in the CGS Combination System 2

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2015   149 - 153  2016

    DOI CiNii

  • Study on simple on-site measurement method of VRF (Part 1) Proposal of measurement using Weighted Average method

    Techinical Papers of Annual Meeting the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   2015   185 - 189  2016

    DOI CiNii

  • A study on probabilistic thermal acceptability evaluation

    Masanari Ukai, Goo Tsusaka, Tatsuo Nobe

    Proceedings - 9th International Windsor Conference 2016: Making Comfort Relevant     985 - 993  2016

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    This study aims to establish a new thermal comfort index for evaluating air-conditioning systems, and introduces a new thermal comfort index for the provided and required temperatures. The authors performed comparison verification experiments on the temperature distribution of radiant air-conditioning and convective air-conditioning systems. The results showed the temperature provided by the convective air-conditioning system to have a wide distribution, unlike that of the radiant air-conditioning system. Based on these results, the authors propose a probabilistic thermal acceptability evaluation using the concepts of "provided temperature" and "required temperature". The authors consider this evaluation method to be applicable for non-steady thermal environments as well as uniform high quality indoor thermal environments using radiant air-conditioning systems, and personalized air-conditioning systems.

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Misc

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Specific Research

  • ひとりひとりが最高の生産性を発揮できるパーソナル空調

    2021  

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    本研究では、執務者が自由に温熱環境を調整できるパーソナル空調に対する動的評価法を考案した。温熱環境の調整手法が着衣による調整に限られた場合、対流空調の環境下において、等価温度の設定値が26.0℃付近における非受容者率が低いが、それでも30%程度の執務者は熱的な不満を感じていると試算された。一方で、パーソナル空調が使用できる場合、タスク域の環境制御範囲が-1.0℃のケースでは設定等価温度26.5℃付近で非受容者率が20%程度となり、タスク域の環境制御範囲が-3.0℃のケースでは設定等価温度が25.5℃から28.0℃の間であれば非受容者率が10%を下回る試算となった。

 

Syllabus

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