• Title/Summary/Keyword: air conditioner

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Impact of Construction Safety Managers and Project Characteristics on Air Conditioning Installation Safety Scores (건설 안전관리자의 특성 및 프로젝트 특성이 에어컨 설치 공사의 안전 점수에 미치는 영향)

  • Uhm, Miyoung;Kim, Jinyoung;Kim, Hongjo
    • Journal of the Korea Institute of Building Construction
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    • v.24 no.3
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    • pp.381-391
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    • 2024
  • This study examined the factors influencing safety scores in air conditioning installation projects, with a specific focus on the characteristics of safety managers and project-specific details. Given the increase in industrial accidents within this sector and the lack of research on smaller-scale operations, this analysis of 7,046 safety data records from Company A aimed to address this gap. The results indicate that the month of project commencement has the most significant impact on safety scores(correlation coefficient of 0.21), followed by the age of the safety manager(correlation coefficient of 0.06). Interestingly, the educational background of the managers did not appear to influence safety outcomes. Furthermore, project cost was found to have a negative correlation with safety scores(-0.1), suggesting that lower-cost projects may be associated with higher risk levels. These findings underscore the importance of developing tailored safety checklists that take into account the specific timing and scale of air conditioning installation projects. Additionally, the results suggest that incorporating both experienced(older) and less experienced(younger) safety managers into safety strategies may be beneficial for achieving optimal safety outcomes. This balanced approach could leverage the strengths of both groups, potentially enhancing overall risk assessment and mitigation efforts.

Effect of Some Soil Conditioners on Soil Physical Properties and Tobacco Growth (토양개량제 시용이 토양물리성과 담배생육에 미치는 영향)

  • 이철환;진정의;한철수
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.41 no.6
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    • pp.685-691
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    • 1996
  • This experiment was conducted to investigate the effect of some soil conditioners, such as polyvinylalcohol(PVA), zeolite and perlite, on the changes of soil physical properties and on tobacco growth in paddy-upland rotated field. Soil conditioners were treated at the rates of 120kg in PVA, 500kg in zeolite and perlite per l0a, respectively. Ratio of soil aggregates formed from the treated plots tended to. be higher than those from the control in the order of PVA > perlite > zeolite. The wet aggregate stability, mean weight diameter, moisture retention and air permeability from the treated plots tended to be higher than those from the control. Amounts of water-stable aggregates of PV A-treated soil increased with higher soil moisture showing a peak at 50% of moisture content. But with respect to particle of size aggregate formed for crop growth and workability in field, it was presumed that 40% of soil moisture content would be most desirable. Visual characters of soil surface throughout the experiment clearly showed that treated soils were maintaining better surface roughness and porosity than control, but difference in water stable aggregates among treated plots tended to be narrowed. The growths of tobacco, espacially its root zone were better in conditioner treated plots than in non-treated plot showing best in PVA-treated soil.

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Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

Effect of Different Cooling System on Performance and Hair Cortisol on Sows under Heat Stress (고온기 분만사 내 냉방 시설의 종류가 모돈의 번식성적 및 스트레스 지표에 미치는 영향)

  • Oh, Seung-Min;Choi, Yo-Han;Kim, Dong-Woo;Ha, Sang-Hun;Kim, Jo-Eun;Jung, Hyun-Jung;Kim, Jin-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.3
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    • pp.160-168
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    • 2021
  • This study was undertaken to determine the effect of different cooling systems on the performance and hair cortisol of sows under heat stress. During a 21-day experiment, a total of 40 multiparous sows (Landrace×Yorkshire; 242.84±2.89 kg) were allotted to 4 treatments, each with 10 replicates (1 sow per pen). The experimental treatments were CP (Cooling pad), AC (Air conditioner), SC (Snout cooling), and MS (Mist spray). We observed an increase in the average daily feed intake during lactation (p<0.05) in the CP and AC treatment groups. AC treatment had the highest (p<0.05) and SC treatment had the lowest (p<0.05) piglet weight at weaning. During lactation, sows administered SC and MS treatments had higher (p<0.05) hair cortisol accumulation, as compared with the AC and CP treatments. Hair cortisol accumulation in piglets during lactation was highest with MS treatment (p<0.05), and lowest after CP treatment (p<0.05). MS treatment had the highest (p<0.05), and AC treatment had the lowest (p<0.05) respiratory rate and rectal temperature during lactation. In conclusion, our results indicate that a cooling pad and air conditioning cooling system increases the productivity of a sow, as compared to snout cooling and mist spray cooling systems.

Analysis of Differences in Indoor Environment and Fatigue Response According to Ventilation in Lecture Hall (대형강의실의 환기여부에 따른 실내환경과 피로감 반응의 차이분석)

  • Oh, Ye-Seul;Hwang, Jin-A;Choi, Yoon-Jung
    • Korean Journal of Human Ecology
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    • v.19 no.2
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    • pp.417-428
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    • 2010
  • The purpose of this study was to analyze differences of the indoor environment and student's fatigue response according to ventilation in university lecture hall. The experiments consisted of measuring the indoor environmental parameters and a survey of student's responses. The experiments were in the lecture hall that the actual lecture was conducted in on the $25^{th}$ of May 2009 (not opening windows and door- A) and the $1^{st}$ of June 2009 (opening windows and door- B). The experimental variable was ventilation by opening the windows and door, and the controlled conditions were indoor temperature by air conditioner, volume of the microphone and VTR, lighting conditions and teaching method. The results are as follows: 1) The indoor temperature was maintained in controlling A, B but the $CO_2$ and relative humidity of A (average 3579ppm, 62.6%) was higher than B (average 1697ppm, 48.1%). 2) There were differences in the student's subjective responses and student's fatigue responses between A and B. 3) Therefore, it was found that ventilation by opening the windows and door was a valid way to improve the relative humidity and to reduce $CO_2$ in the lecture hall.

Technology for Real-Time Identification of Steady State of Heat-Pump System to Develop Fault Detection and Diagnosis System (열펌프의 고장감지 및 진단시스템 구축을 위한 실시간 정상상태 진단기법 개발)

  • Kim, Min-Sung;Yoon, Seok-Ho;Kim, Min-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.4
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    • pp.333-339
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    • 2010
  • Identification of a steady state is the first step in developing a fault detection and diagnosis (FDD) system of a heat pump. In a complete FDD system, the steady-state detector will be included as a module in a self-learning algorithm, which enables the working system's reference model to "tune" itself to its particular installation. In this study, a steady-state detector of a residential air conditioner based on moving windows was designed. Seven representative measurements were selected as key features for steady-state detection. The optimized moving-window size and the feature thresholds were decided on the basis of a startup-transient test and no-fault steady-state test. Performance of the steady-state detector was verified during an indoor load-change test. In this study, a general methodology for designing a moving-window steady-state detector for applications involving vapor compression has been established.

An Investigation of Ingredients and Hazardous Substances in Some Consumer Products - Focusing on Cleaners and Disinfectants - (일부 생활화학용품에 함유된 성분 및 유해물질 조사 - 세정제와 소독제를 중심으로 -)

  • Heo, Da-An;Huh, Eun-Hae;Park, Ji Young;Moon, Kyong Whan;Lee, Kiyoung
    • Journal of Environmental Health Sciences
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    • v.41 no.5
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    • pp.314-326
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    • 2015
  • Objectives: This study was conducted to identify the ingredients used in ten consumer product categories and determine hazardous substances among these ingredients. Methods: A total of 542 commercial products in ten consumer product categories were selected. The consumer products were sticker removers, washing machine cleaners, multi-purpose cleaners, mold removers, glass cleaners, chlorinated sanitizers, air conditioner cleaners, disposal cleaners, drain cleaners and disinfectant sprays. The company list was complied from governmental records and a market survey. The respective companies were contacted for a list of ingredients found in the 542 products. Results: The corresponding companies listed 163 ingredients. According to European Union (EU) Directive 67/548/EEC, 38 of the 163 ingredients were classified as dangerous substances. Among these substances, 28 ingredients were hazardous to the skin, 15 were hazardous to the eye, and nine were hazardous if inhaled. Three ingredients were classified as CMR (carcinogenic, mutagenic or toxic for reproduction) substances: liquefied petroleum gases (LPG) with carcinogenicity and mutagenicity, and VM&P naphtha and ligroine with carcinogenicity. Conclusion: Various chemicals, including hazardous substances, were used in consumer products. Risk assessment of consumer products is required in order to protect the population from health risks.

Assessment of Thermal Comfort in a General Hospital in Winter Using Predicted Mean Vote (PMV) (Predicted Mean Vote(PMV)를 이용한 겨울철 종합병원의 실내 온·열 환경의 평가)

  • Lee, Boram;Kim, Jeonghoon;Kim, KyooSang;Kim, Hyejin;Lee, Kiyoung
    • Journal of Environmental Health Sciences
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    • v.41 no.6
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    • pp.389-396
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    • 2015
  • Objectives: A hospital is a complex building that serves many different purposes. It has a major impact on patient's well-being as well as on the work efficiency of the hospital staff. Thermal comfort is one of the major factors in indoor comfort. The purpose of this study was to determine thermal comfort in various locations in a hospital. Methods: Various indoor environmental conditions in a general hospital were measured in February 2014. The predicted mean vote (PMV) and carbon dioxide ($CO_2$) concentration were measured simultaneously in the lobby, office, restaurant, and ward. Results: The ward was the most thermally comfortable location (PMV=0.44) and the lobby was the most uncomfortable (PMV = -1.39). However, the $CO_2$ concentration was the highest in the ward (896 ppm) and the lowest in the lobby (572 ppm). The average PMV value was the most comfortable in the ward and the lowest in the lobby. In contrast, for concentration of carbon dioxide, the highest average was in the ward and the lowest in the lobby. Due to air conditioner operation, during operating hours the PMV showed values close to 0 compared to the non-operating time. Correlation between PMV and $CO_2$ differed by location. Conclusion: The PMV and concentration of carbon dioxide of the hospital lobby, office, restaurant and ward varied. The relationship between PMV and carbon dioxide differed by location. Consideration of how to apply PMV and carbon dioxide is needed when evaluating indoor comfort.

A Study on Relationships Between Residential Environments and the Social Maturity of Middle School Students (중학생의 주거 환경과 사회적 성숙도와의 관계 연구)

  • Kim, See-Hee;Kwark, Kyung-Sook
    • Korean Journal of Human Ecology
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    • v.19 no.1
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    • pp.215-225
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    • 2010
  • This study had the purpose of presenting a residential environment solution as a desirable educational environment for middle school students to grow soundly and to achieve proper self-realization while providing basic materials to build up a suitable residential environment by comparing and analyzing what relationships exist between different home backgrounds, residential environments and middle school students' social maturity. This research was conducted from Feb. 11, 2008 to Feb. 13, 2008. The subject of this research was 601 students in 3 middle schools located in Gyunggi-do. The data analyzed used the SPSS 11.5 version. The summary of this study's results is as follows. First, in terms of home background, the higher the parents' educational background and social and economic position, the greater the students' social maturity. Second, in terms of home environment, the more spacious the living space, the better the water and sewage system and rest room, the more convenient the air conditioner and kitchen system, the better the lighting, ventilation, soundproofness, insulation, the less the danger in relation to fire, crime, traffic accidents, disaster, the greater the students' social maturity. Third, in terms of the home environment related to the correlation between the residential environment and social maturity, all areas such as housing facilities, housing structural environment and housing safety showed static correlations and proved that the residential environment has an important influence on social maturity. Accordingly, in order to build up an ideal residential environment, we should make efforts to expand and improve better facilities at home considering privacy, lighting, ventilation, soundproofness, heating etc. and remove unsound factors that obstruct students social maturity and build up clean and safe residential environment with good relations with their neighbors.

Economic Analsys of Cooling-Heating System Using Ground Source Heat in Multi Family Apartment (공동주택에서 지열 냉난방 시스템 적용시 경제성 분석)

  • Park, Yongboo;Park, Jongbae;Lim, Haesik;Baek, Sungkoon
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.3
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    • pp.11-18
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    • 2007
  • This paper studied the economical efficiency of ground source heat pump system under various conditions in apartments which have important effects on the housing market. And this study analysed the initial cost increase, saved managing cost and recovery time of initial cost. Analysis result showed as time of heating-cooling and water heating increases, the amount of saved managing cost increased much than the initial construction cost, so recovery time shortened. And as the net area of apartment increases, the recovery time increased. The study of the relation between the installation type and recovery time of initial construction cost showed when heat-cooling system adapted ground source heat and water heating system adapted waste heat, the initial construction cost was recovered most quickly. When Ground Source Heating system was used for the heating-cooling and water heating system, ground source heating system was used for the heating-cooling and waste heat used for water heating, and ground source heating system was used for the heating-cooling and LNG used for water heating, the construction cost increased 72,000, 66,900 and 62,300 won each per $m^2$ compared to the current system (package air-conditioner, heating and water heating using LNG).

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