• 한국조경학회지
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• 제43권5호
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• pp.65-73
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• 2015

조경용 차양막의 명도가 하절기 옥외공간에서 인간이 느끼는 온열쾌적성에 어떤 영향을 미치는 지를 객관적으로 검증하기 위하여 흑색과 백색 차양막으로 2.5m의 피라미드형 시험구를 조성하여 그 하부 공간의 평균복사온도 변화 특성을 비교 분석하였다. 그리고 현실적인 적용가능성을 검토하기 위하여 95% 일사차단율의 농업용 통기성 흑색 차양망 하부와 비교 검토하였다. 지면으로부터 1.1m, 1.7m, 2.4m 지점에서 계측된 평균복사온도를 비교한 결과, 차양이 없는 대조구의 평균복사온도가 $41.8^{\circ}C$일 때, 막면과 인접한 지상 2.4m 지점의 평균복사온도는 흑색 및 백색막과 통기성 흑색망에서 각각 $49.1^{\circ}C$, $41.6^{\circ}C$, $36.8^{\circ}C$로 분석되어, 흑색막 아래의 값이 현저히 높은 것으로 나타났다. 그러나, 실제 사람이 체감하는 범위인 지상 1.7m 지점의 평균값은 $37^{\circ}C$, $38^{\circ}C$, $33^{\circ}C$로 분석되어 재료의 명도에 의한 차이는 크지 않은 것으로 나타났는데, 이 높이 이하의 위치에서는 흑색막보다 백색막 아래의 평균복사온도 값이 미세하게나마 높은 것으로 나타났다. 통기성 흑색망의 경우 모든 높이에서 가장 낮은 평균복사온도를 보여서 하절기 열환경 개선측면에서 가장 효과적인 것으로 나타났다. 시험에 사용된 차양막 소재의 일사 반사 및 흡수 특성을 분석한 결과, 동일 소재라도 색상의 밝기에 따라서 일사의 반사율과 흡수율, 투과율에서 차이가 발생됨이 확인되었다. 흑색막의 경우, 일사 반사율은 낮고, 흡수율은 높아 막 자체의 온도가 현저히 높아지는 것으로 나타난 반면, 일사 투과율은 상대적으로 낮은 것으로 평가되었다. 백색막의 경우, 일사반사율은 높은 반면, 일사 흡수율이 낮아 막면 자체의 온도는 상대적으로 낮았으나, 일사투과율은 상대적으로 높은 것으로 평가되었다. 결과적으로 막면의 장파복사량과 표면온도는 흑색이 높게 나타났으나, 실제 사람들의 체감 범위에서의 평균복사온도는 흑색막 아래가 미세하게나마 더 낮아지는 결과가 나타난 것은 백색막의 상대적으로 높은 일사투과율의 영향인 것으로 판단되었다.

• 한국조경학회지
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• 제45권2호
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• pp.60-67
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• 2017

하절기 옥외공간에서 조경용 차양 소재의 공극률 차이에 따른 온열환경의 개선 효과를 객관적 물리량으로 검증하기 위해, 도심 건물 옥상에 조성된 암상자 상단에 공극률을 달리한 흑색 막소재의 차양을 설치하고, 그 하부의 평균복사온도의 차이를 계측하여 비교하였다. 적용된 공극률은 각각 0.5, 1. 2, 4, 8, 16, 32% 였으며, 2016년 8월에서 11월까지 세 조씩 순차적으로 비교되었다. 일 최고 흑구온도가 $30^{\circ}C$ 이상인 날의 오전 11시부터 오후 3시까지의 자료를 비교한 결과, 차양과 측벽이 설치되지 않는 개방구의 평균복사온도가 $44.26^{\circ}C$일 때, 무측벽-유차양구, 유측벽-무차양구, 유측벽-유차양구의 값은 각각 33.08, 45.80, $42.03^{\circ}C$로 차양과 측벽 유무에 의한 명확한 차이가 확인되었다. 측정 시기별 평균복사온도 기준치를 보정하기 위하여 대조구의 값을 공변량으로 공극률에 따른 값을 공분산분석(ANCOVA)한 결과, 유측벽-무차양구의 평균 값이 $45.80^{\circ}C$일 때, 0.5, 1, 2, 4, 8, 16, 32% 공극률 차양 하부의 값은 각각 43.40, 43.10, 41.49, 40.43, 39.61, 37.91, $38.12^{\circ}C$로 계산되었다. 공극률과 평균복사온도 사이에는 약 22.5%의 공극률을 최저점으로 하는 U자형의 2차 함수의 관계가 있는 것으로 분석되었다. 결론적으로, 본 연구를 통해서 차양의 공극률이 높아질수록 일정 수준까지는 평균복사온도를 저감시키는 효과가 있음을 확인할 수 있었으며, 그 한계값은 물리적 측정치로는 16%였으며, 통계적 추정치로는 약 22.5%였다.

• 설비공학논문집
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• 제22권7호
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• pp.492-507
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• 2010

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2009. 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) Research trends of thermal and fluid engineering have been surveyed as groups of general thermal and fluid flow, fluid machinery and piping, and new and renewable energy. Various topics were covered in the field of general thermal and fluid flow such as an expander, a capillary tube, the flow of micro-channel water blocks, the friction and anti-wear characteristics of nano oils with mixtures of refrigerant oils, etc. Research issues mainly focused on the design of micro-pumps and fans, the heat resistance reliability of axial smoke exhaust fans, and hood systems in the field of fluid machinery and piping. Studies on ground water sources were executed concerning two well type geothermal heat pumps and multi-heat pumps in the field of new and renewable energy. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics and industrial heat exchangers. Researches on heat transfer characteristics included the heat transfer in thermoelectric cooling systems, refrigerants, evaporators, dryers, desiccant rotors. In the area of industrial heat exchangers, researches on high temperature ceramic heat exchangers, plate heat exchangers, frosting on fins of heat exchangers were performed. (3) In the field of refrigeration, papers were presented on alternative refrigerants, system improvements, and the utilization of various energy sources. Refrigeration systems with alternative refrigerants such as hydrocarbons, mixed refrigerants, and $CO_2$ were studied. Efforts to improve the performance of refrigeration systems were made applying various ideas of suction line heat exchangers, subcooling bypass lines and gas injection systems. Studies on heat pump systems using unutilized energy sources such as river water, underground water, and waste heat were also reported. (4) Research trend in the field of mechanical building facilities has been found to be mainly focused on field applications rather than performance improvements. In the area of cogeneration systems, papers on energy and economic analysis, LCC analysis and cost estimating were reported. Studies on ventilation and heat recovery systems introduced the effect on fire and smoke control, and energy reduction. Papers on district cooling and heating systems dealt with design capacity evaluation, application plan and field application. Also, the maintenance and management of building service equipments were presented for HVAC systems. (5) In the field of architectural environment, various studies were carried to improve indoor air quality and to analyze the heat load characteristics of buildings by energy simulation. These studies helped to understand the physics related to building load characteristics and to improve the quality of architectural environment where human beings reside in.

• 한국환경보건학회지
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• 제42권2호
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• pp.92-101
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• 2016

Objectives: Outdoor workers are exposed to thermally stressful work environments. In this study, heat stress indices for harbor workers in summer were calculated to evaluate thermal comfort based on a human heat balance model. These indices are Physiological Subjective Temperature (PST), Dehydration Risk (DhR), and Overheating Risk (OhR) according to respective stage of cargo work in a harbor. In addition, we constructed a forecast system to provide heat stress information. Methods: Thermophysiological indices in this study were calculated using the MENEX model (i.e. the human heat balance model), which used as inputs the meteorological parameters, clothing insulation, and metabolic rate for each stage of cargo work in the harbor of Masan over the course of seven days, including a four-day heat wave. The forecast heat stress information constructed for Masan harbor was based on meteorological data supported by the Dong-Nae Forecast from the KMA (Korea Metrological Administration) and other input parameters. Results: According to higher metabolic rate, thermophysiological indices showed a critical level. In particular, PST was evaluated as reaching the 'Very hot' or 'Hot' level during all seven days, despite the heat occurring over only four. It is important in a regard to consider the work environment conditions (i.e. labor intensity and clothing in harbor). On a webpage, the forecast thermophysiological indices show as infographics to be easily understand. This webpage is comprised of indices for both current conditions and the forecast, with brief guidance. Conclusion: Thermophysiological indices show the risk level to health during a heat wave period. Heat stress information could help to protect the health of harbor workers. Further, this study could extend the applicability of these indices to a variety of outdoor workers in consideration of work environments.

• Asian-Australasian Journal of Animal Sciences
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• 제30권5호
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• pp.749-754
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• 2017

Objective: The objective of the present study was to investigate the effects of farrowing month (FM), parity and sex on the growth performance of Berkshire swine raised in alternative production systems. Methods: A total of 40 farrowing records from 27 sows and 1,258 body weight (BW) records from 274 piglets collected over a two-year period were used for the analysis. The BWs were recorded at birth, weaning (28 d), 56, 84, 112, and 140 days. Any BW not recorded on schedule was recalculated to conform the days of age among corresponding BW records, using growth curves drawn with polynomial functions whose power was determined by the number of existing observations for each individual. Results: The mean parity (${\pm}$standard deviation) of the sows was $3.42{\pm}2.14$. The sows that farrowed in June had the lowest number of total born with an average of $6.25{\pm}2.22$ piglets per sow. However, the lowest average number of piglets weaned at day 28 was found in sows that farrowed in May, as well as the highest number recorded for the stillborn piglets with an average of 2.67 piglets per sow. Moreover, the smallest increase in weight from birth to weaning occurred in piglets that were farrowed in May, which also corresponds with the average daily gain (ADG) of 0.29 kg and the last recorded weight measurement on day 140 of $41.69{\pm}1.45kg$. Contrastingly, the highest growth rate was found among pigs farrowed in June, with the largest increase in weight of 7.55 kg from birth to weaning, the highest ADG of 0.51 kg from birth to 140 day of age and the highest BW of $74.70{\pm}1.86kg$ recorded on day 140. Conclusion: Pigs farrowed in June also had the least number of piglets that died between birth and weaning. The zone of thermal comfort found in sows reared in indoor confinement systems did not improve the reproductive performance of the sows reared in an outdoor, alternative production system, while the growth performance of the piglets was improved when the ambient temperature was consistently hot or consistently cold.

• 한국의류산업학회지
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• 제7권3호
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• pp.321-326
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• 2005

The purpose of this study was to investigate the effect of body fat on energy metabolic response and subjective sensations under the hot environment. Fifteen female university students volunteered as subjects. We organized subjects into three groups: low body fat group(group L : less than 20% of body fat), medium body fat group(group M : 20%~30% of body fat) and high body fat group(group H: more than 30% of body fat). The experiment was conducted with $32^{\circ}C$, 60%RH. The subjects repeated 'Exercise' and 'Rest' period. The results of this study are as follows ; The oxygen uptake value of AM is higher than PM. The value of group H is the highest in three fat groups. But it showed group L is the highest in oxygen uptake per weight. %body fat is the lower, oxygen uptake is the higher. In Calorie, group L has higher value in AM in than in PM. In M group and group H, a value of PM is higher than AM. In group H, difference of AM and PM is the highest. From a view point of three groups, a value of group H is the highest. This support that calorie increases as oxygen uptake increase. The heart rate values of group L and group H are the higher in AM than in PM. This support that heart rate was relation to oxygen uptake. In all three groups, the value of blood pressure is higher in AM than in PM. Subjective sensations of temperature sensation, thermal comfort, and wetness sensation are higher in Am than in Pm. This explains that subject sensations are similar to experimental data, such as oxygen uptake, heart rate, blood pressure. In oxygen uptake, heart rate and blood pressure, general tend to showed higher AM than PM. This showed that heart rate, oxygen uptake increase in AM, as blood pressure increase, too. From a view point of %body fat, group H is higher than the others in oxygen uptake, heart rate and blood pressure.

• 설비공학논문집
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• 제20권12호
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• pp.844-861
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• 2008

The papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during the year of 2007 have been reviewed. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro nano fluid, micropump and fuel cell. Traditional CFD was still popular and widely used in research and development. Studies about fans and pumps were performed in the field of fluid machinery. Characteristics of flow and fin shape optimization are studied in the field of piping system. (2) The research works on heat transfer have been reviewed in the field of heat transfer characteristics, heat exchangers, and desiccant cooling systems. The research on heat transfer characteristics includes thermal transport in pulse tubes, high temperature superconductors, ground heat exchangers, fuel cell stacks and ice slurry systems. For the heat 'exchangers, the research on pin-tube heat exchanger, plate heat exchanger, condensers and gas coolers has been cordially implemented. The research works on heat transfer augmenting tubes have been also reported. For the desiccant cooling systems, the studies on the design and operating conditions for desiccant rotors as well as performance index are noticeable. (3) In the field of refrigeration, many papers were presented on the air conditioning system using CO2 as a refrigerant. The issues on the two-stage compression, the oil selection, and the appropriate oil charge were treated. The subjects of alternative refrigerants were also studied steadily. Hydrocarbons, DME and their mixtures were considered and various heat transfer correlations were proposed. (4) Research papers have been reviewed in the field of building facilities by grouping into the researches on heat and cold sources, air conditioning and air cleaning, ventilation and fire research including tunnel ventilation, flow control of piping system, and sound research with drain system. Main focuses have been addressed to the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies were mostly focused on analyzing the indoor environment in various spaces like cars, old tombs, machine rooms, and etc. in an architectural environmental field. Moreover, subjects of various fields such as the evaluation of noise, thermal environment, indoor air quality and development of energy analysis program were researched by various methods of survey, simulation, and field experiment.