운량에 따른 대구지방의 야간 천공온도 산정

나욱호,이종원,소레이멘디옵,이현우,Na, Wook-Ho,Lee, Jong-Won,Diop, Souleymane,Lee, Hyun-Woo 경북대학교 농업과학기술연구소 2013 慶北大農學誌 Vol.31 No.1

본 연구의 목적은 온실설계 시 야간복사열 손실량 예측을 위한 천공온도를 산정하는데 필요한 적절한 계산식을 제시하는 것이다. 대구지역의 운량에 따른 야간천공온도를 야간복사계를 이용하여 측정하고 기존의 식들을 이용하여 계산하였다. 천공온도를 계산하기 위한 최적의 식을 찾아내기 위하여 측정값과 계산 값을 비교하였다. 운량의 크기에 따라 대기온도와 천공온도의 차이가 달랐으며 운량이 감소함에 따라 온도차는 점차 증가하였다. 맑은 날이 구름 낀 날과 비온 날에 비해 약 10~20배 정도의 더 높은 온도차를 나타내었으며 온도차가 큰 맑은 날이 복사냉각이 크다는 것을 확인할 수 있었다. 맑은 날에 대하여 계산된 천공온도와 측정된 천공온도와의 상관성을 분석한 결과 Bliss식과 Clark and Allen 식이 다른 식들에 비해 상관성이 비교적 더 높은 것으로 나타났다. 구름낀 날에 대해 계산된 천공온도와 측정온도와의 상관성을 분석한 결과 Fuentes 식이 가장 잘 맞는 것으로 나타났다. 구름낀 날의 천공온도를 산정할 수 있는 새로운 식을 제안하였다. To estimate the radiative heat loss from greenhouses, a new equation for calculating the sky temperature is presented. The sky temperature in the Daegu region was measured using a pyrgeometer and calculated using different equations according to the cloudiness. The calculated and measured results were then compared to identify the best equation for calculating the sky temperature. The difference value between the air and sky temperature was dissimilar and increased as the cloud amount decreased. On clear days the difference value was 10~20 times greater than that on cloudy and rainy days. When analyzing the correlationship between the calculated and measured sky temperatures on clear days, Bliss's and Clark & Allen's equations were found to be superior to the other equations. However, on cloudy days, the best correlationship between the calculated and measured sky temperatures was exhibited by Fuentes's equation. Therefore, a new equation is proposed for calculating the sky temperature on a cloudy day.

온실의 구조설계용 작물하중 산정

나욱호(Wook-Ho Na),이종원(Jong-Won Lee),라쉬드아드난(Adnan Rasheed),곽철순(Cheul-Soon Kwak),이시영(Si-Young Lee),윤용철(Yong-Cheol Yoon),이현우(Hyun-Woo Lee) (사)한국생물환경조절학회 2017 시설원예‧식물공장 Vol.26 No.4

본 연구에서는 온실의 구조설계용 작물하중을 산정하는데 필요한 기초자료를 제공하기 위하여 각국의 온실구조설계용 작물하중 기준들을 비교분석하고 여러 가지 온실작물들에 대하여 작물하중을 직접 측정하고 분석하였다. 설계 작물하중에 대한 각국의 기준들을 비교분석한 결과 나라들 마다 서로 많은 차이를 보여주고 있으며, 우리나라 기준들은 외국의 기준들을 그대로 인용하고 있는 것으로 나타나 우리나라 실정에 맞는 작물하중 기준이 제시될 필요가 있다고 판단된다. 최대 주당 작물하중이 토마토는 두 가지 온실에서 각각 3.3kgf·plant<SUP>-1</SUP>와 3.9kgf·plant<SUP>-1</SUP>로 나타났고, 오이는 0.75kgf·plant<SUP>-1</SUP>, 가지는 1.9kgf·plant<SUP>-1</SUP>, 딸기는 재배베드를 포함하여 2.1kgf·plant<SUP>-1</SUP> 으로 나타났다. 단위면적당 작물하중은 토마토가 평균 8.5kgf·m<SUP>-2</SUP>으로 나타났고, 오이와 가지는 각각 2.1kgf·m<SUP>-2</SUP>과 2.4kgf·m<SUP>-2</SUP>으로 토마토의 하중보다 훨씬 낮게 나타났다. 우리나라 온실설계기준에 제시된 작물하중은 토마토와 오이의 경우 15kgf·m-2으로 본 연구에서 측정된 값보다 훨씬 높았다. 우리나라의 설계기준이 네덜란드의 기준을 그대로 인용한 것으로 판단되기 때문에 이러한 차이를 고려하여 우리나라의 작물하중 설계기준에 대한 재검토가 이루어져야 할 것으로 판단된다. 딸기의 작물하중은 행잉베드를 포함한 중량이 21.0kgf·m<SUP>-2</SUP>로 네덜란드의 설계기준인 30kgf·m<SUP>-2</SUP>보다 훨씬 작았다. This study was conducted to provide basic data needed to calculate the crop loads for the greenhouse design. Four countries’ crop loads for greenhouse structures were compared and the crop loads were measured directly and analyzed for various greenhouse crops, including tomato, strawberry, cucumber, and eggplant. According to the analysis results of four country’s standards for the design crop loads, it was judged that the new design crop loads suit for greenhouse crops in our country should be suggested because our standards just used the design crop loads of other countries. The maximum crop loads per plant of tomato, cucumber, eggplant, and strawberry were 3.9, 0.75, 1.9 and 2.1 kgf·plant<SUP>-1</SUP>, respectively. The crop load per unit area of tomato was 8.5 kgf·m<SUP>-2</SUP>, which was much greater than the cucumber and eggplant’s crop load of 2.1 and 2.4 kgf·m<SUP>-2</SUP> respectively. The crop loads of tomato and cucumber, suggested by the greenhouse structure design standard of Korea, is 15 kgf·m<SUP>-2</SUP>, which is far greater than the values suggested by this research. It was judged that this was because our standard just used the Dutch standard, our crop load standard should be reviewed considering this difference. The crop load of strawberry, including the growing bed, was 21.0 kgf·m<SUP>-2</SUP>, which was much greater than the crop load in the Dutch standard.

대구시 하수종류에 따른 하수처리장 운전실태 및 중수도 시설 도입 방안에 관한 연구

나욱호(Na Wook-Ho),최미영(Choi Mi-Young),도형윤(Do Hyung-Ryun),홍원화(Hong Won-Hwa) 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

It apparently appear water resources necessity rate rapidly, developing system and densified city, increasing population. Further water resource is expected to needed more than current requiring rate. On this matter, there are considered the hygiene water(graywater) operation by classifying as the objectivity and the scale due to the fact sewage is supplied as closed distance in city and settled quantity. This way which sewage is used as quantitative resource and increased operation efficiency that some screening systems have not been properly installed and that virtually raw sewage is being discharged in right place. This method leads secured water resource and easily developed the water type as a secondly treatment as well as reducing treatment expense by defining water type, decreasing a environmental demage risk. The research has focused on this point to analysis the graywater statue in terms of treatment process, systemic operation and the using logistics on based on figure supplied by Daegu City sewage Agency. That data which have obtain through this case study will provide the optimal size facilities of graywater in developing country, especially Korea is crucial step to make a master plan for national water resource.

대구시 하수처리장 운전실태에 따른 중수도 도입 방안 연구

최미영,나욱호,홍원화,김삼열,Choi Mi-Young,Na Wook-Ho,Hong Won-Hwa,Kim Sam-Yeul 한국주거학회 2005 한국주거학회 논문집 Vol.16 No.1

It has seen the significant increase of water consumption rate due to rapid industrialization, high-densities of city, and increasing the population; thereby leads further water resource required in near future. In order to solve this deficit there are one of solution that gray water method demonstrates advantages regarding the questions of optimal water utility and thereby master plan of water. The method of study is analysis of investigation data through interview and research of sewage treatment plants in Daegu City. Through these analysis, this paper examines the capacity of graywater and optimal graywater facility.

딸기 고설재배용 베드 재료별 근권부 온도 변화

이종원(Jong-Won Lee),나욱호(Wook-Ho Na),이현우(Hyun-Woo Lee) 한국원예학회 2013 한국원예학회 학술발표요지 Vol.2013 No.10

온실 난방용 튜브 네트워크 및 팬 코일 장치를 사용하는 히트 펌프 시스템의 성능 평가

미스바딘아데레미아데산야 ( Misbaudeen Aderemi Adesanya ),나욱호 ( Wook-ho Na ),아니스라비우 ( Anis Rabiu ),카짐오페에미오군로 ( Qazeem Opeyemi Ogunlowo ),티모시데넨악펜푼 ( Timothy Denen Akpenpuun ),윤용철 ( Yong-cheol Yoon ),이현우 ( Hyun-woo 한국농공학회 2022 한국농공학회 학술대회초록집 Vol.2022 No.-

Energy consumption in greenhouse accounts for about 40-50% of the total production cost in many countries. Saving energy and reducing greenhouse gas emissions (GHG) in the food supply chain are part of the sustainable development goals to reduce the bottlenecks in the agricultural energy-sector. Several countries have made concerted effort for the improvement of greenhouse efficiency by replacing the traditional carbon-based energy systems with heat pump systems (HPS). The South Korean government has planned to key into this policy by proposing a reduction of GHG to 18.1% by 2030 and completely neutralizing it by 2050, through continuous application of HPS in the energy-consuming sector. This study, through experimental investigation, analyzes the performance of six integrated HPS installed at Yeoju-si, Gyeonggi-do, western South Korea. The HPS use night thermal energy storage (NTES) as a buffer and tube rails and fan coil units as terminal units to supply hot water to the greenhouse. Two of the HPS are ground source heat pumps (GSHP) while others are hybrid heat pumps (HHP) using air as air source heat pump (ASHP) and evaporative heat source from tank thermal energy storage (TTES) and borehole thermal energy storage (BTES). The average monthly coefficient of performance (COP) of the ASHP varies between 0.94 - 2.32. It has the lowest value of 0.94 due to defrosting operation in January when the mean monthly temperature was -3.6 ℃. The GSHP has the highest COP ranging from 3.24 - 3.84, then HHP using heat source from BTES, 1.84 - 2.84 and TTES, 1.17 - 2.68. During the investigation, at least 50 ℃ water temperature was maintained in the NTES. In extreme low weather conditions, electric boiler installed between the NTES and the greenhouse increases the inlet tube water temperature to constant 55 ℃. The HPS configuration supplied 85% of the total energy consumed by the greenhouse in the coldest month, reducing the GHG that would have been emitted if the energy supply system was completely carbon-based. The terminal unit capacity compared with other tube emission standards was also sufficient to maintain the greenhouse internal temperature and is recommended for future use and further study.

Overall Heat Transfer Coefficient Measurement of Covering Materials with Thermal Screens for Greenhouse using the Hot Box Method

소레이멘 디옵,이종원,나욱호,이현우,Diop, Souleymane,Lee, Jong-Won,Na, Wook-Ho,Lee, Hyun-Woo The Korean Society of Agricultural Engineers 2012 한국농공학회논문집 Vol.54 No.5

본 연구의 목적은 국내에서 상용되고 있는 온실 피복재 및 보온재의 조합에 따른 관류열전달계수를 핫박스를 이용하여 평가하는 것이다. 온실용 일중 및 이중 피복재와 이중 보온재의 조합에 대하여 야간천공복사 차단여부에 따른 관류열전달계수를 핫박스를 이용하여 실외에서 측정하였다. 처리조건은 일중피복, 이중피복, 이중피복과 이중 마트보온재 및 이중피복과 이중 다겹보온재의 조합조건과 천공복사 유무에 따른 조건이며 총 8가지이다. 제작된 핫박스는 상시 변화하는 외부의 기상조건하에서도 내부온도를 설정된 온도로 일정하게 잘 유지할 수 있었다. 온실 피복재 및 보온재의 관류열전달계수를 측정하는 실내용 측정장치는 반드시 야간천공복사를 모의할 수 있는 측정장치가 되어야 할 것이다. 야간복사를 차단함으로서 온실의 열 손실을 줄여 보온효과를 얻을 수 있을 것으로 분석되었다. 모든 피복방식에 대해 야간복사 차단장치 유무에 관계없이 높은 풍속에서의 관류열전달계수가 낮은 풍속에서보다 더 큰 것으로 나타났다. 본 연구에서 사용된 측정기법을 사용하면 국내에서 생산되는 피복재 및 보온재의 관류열전달 특성을 정량적으로 비교할 수 있을 것으로 기대된다.

Measurement of Convective Heat Transfer Coefficients of Horizontal Thermal Screens under Natural Conditions

Adeel Rafiq(라피크아딜),Wook Ho Na(나욱호),Adnan Rasheed(라쉬드아드난),Hyeon Tae Kim(김현태),Hyun Woo Lee(이현우) (사)한국생물환경조절학회 2020 생물환경조절학회지 Vol.29 No.1

대류열전달은 겨울철 온실 열손실의 중요한 원인이 되며, 일반적으로 복사열에 의한 손실보다 더 크다. 스크린의 대류열전달계수를 자연상태에서 측정한 연구가 수행된 바는 있지만 상하면의 재질이 동일하고 공극이 없는 스크린에 대해서는 적용을 할 수 없는 방법이다. 이러한 재질의 스크린은 한국에서 많이 사용되고 있으나 대류열전달 특성을 파악하는데 많은 어려움이 있는 실정이다. 본 연구에서는 공극이 없는 3가지 종류의 스크린에 대해 대류열전달계수를 구하였으며, 계수를 산정하기 위하여 복사열수지 이론에 근거하여 산정방법을 개발하였다. 실험장치에 스크린을 설치하고 일사량, 장파복사량, 대기온도, 스크린 및 흑색천의 표면온도, 풍속 등을 측정하였다. 스크린의 표면온도와 주변온도의 차이에 따른 대류열전달계수를 산정하였다. 풍속이 거의 없는 상태에서 온도의 차이가 증가함에 따라 계수는 감소하는 것으로 나타났다. Convective heat transfer is the main component of greenhouse energy loss because the energy loss by this mechanism is greater than those of the other two components (radiative and conductive). Previous studies have examined the convective heat transfer coefficients under natural conditions, but they are not applicable to symmetric thermal screens with zero porosity, and such screens are largely produced and used in Korea. However, the properties of these materials have not been reported in the literature, which causes selectivity issues for users. Therefore, in this study, three screens having similar color and zero porosity were selected, and a mathematical procedure based on radiation balance equations was developed to determine their convective heat transfer coefficients. To conduct the experiment, a hollow wooden structure was built and the thermal screen was tacked over this frame; the theoretical model was applied underneath and over the screen. Input parameters included three components: 1) solar and thermal fluxes; 2) temperature of the screen, black cloth, and ambient air; and 3) wind velocity. The convective heat transfer coefficients were determined as functions of the air–screen temperature difference under open-air environmental conditions. It was observed from the outcomes that the heat transfer coefficients decreased with the increase of the air–screen temperature difference provided that the wind velocity was nearly zero.

TRNSYS 및 Hotbox 방법을 이용한 온실 스크린의 관류열전달계수 평가

아니스라비우 ( Anis Rabiu ),나욱호 ( Wook Ho Na ),아드난라시드 ( Adnan Rasheed ),미스바우딘아데레미아데산야 ( Misbaudeen Aderemi Adesanya ),카짐오페에미오군로 ( Qazeem Opeyemi Ogunlowo ),( Timothy Denen Akpenpuun ),이현우 ( Hyun-woo Lee ) 한국농공학회 2022 한국농공학회 학술대회초록집 Vol.2022 No.-

The high energy consumption in the greenhouse during the winter season dictates a need to develop various thermal screens for energy-saving purposes. However, there is limited data on the precise properties of thermal screens, while little research has investigated a methodological approach for measuring the screen’s energy-saving capacity for greenhouse energy efficiency. This research aims to investigate the thermophysical, radiative, and aerodynamic properties of selected commercial greenhouse thermal screens. The TRNSYS model was used to simulate the heat flux and derive the thermal retention qualities of the thermal screens through their measured properties. The model was validated by comparing the simulated and experimental heat transfer coefficients, expressed as the U-values, thereby determining the thermal retention of the screens. In addition, the simulated U-value was compared to the experimental U-value in material permeability to examine the influence of screen porosity on heat loss. The statistical analysis t-test was conducted to compare the U-values obtained from the simulation and the experimental hotbox. The simulation U-values (for computed permeability) indicated that samples M1 and M3 exhibited the lowest U-value of 4.4 W m?? K??, while white polyester, Luxous, PH-super, PH-66, M2, Clima45(0), and New-Lux showed higher U-values of 82%, 105%, 161%, 123%, 41%, 102%, and 118%, respectively. The R² value of 0.88 indicated the model’s fitness using the coefficient of variation. Because of their low material porosity, M1, M2, and M3 samples showed better greenhouse thermal retention over others. Conclusively, the permeability features of the greenhouse energy screen materials have a substantial impact on their U-values.

TRNSYS에서 분할된 온실 모델의 정확도에 대한 분할면 특성의 영향

카짐오페에미오군로오 ( Qazeem Opeyemi Ogunlowo ),나욱호 ( Wook Ho Na ),아니스라비우 ( Anis Rabiu ),미스바우딘아데레미아데산야 ( Misbaudeen Aderemi Adesanya ),티모시데넨악펜푼 ( Timothy Denen Akpenpuun ),김현태 ( Hyeon Tae Kim ),이현우 ( Hyun Woo 한국농공학회 2022 한국농공학회 학술대회초록집 Vol.2022 No.-

TRNSYS is a common tool that has been recently used to model and simulate greenhouse energy demand and utilization using building energy simulation (BES). Previously, a single thermal point was used for validation without considering the distribution of greenhouse climate parameters, especially the temperature. Often, temperature variation leads to thermal stratification, which has prompted researchers to propose volume discretization in dynamic greenhouse simulation. The effect of surface characterization defined by TRNSYS on the accuracy of such discretized BES model needs to be investigated. Therefore, the objectives of this study are to develop discretized BES models based on surface characterization defined in TRNSYS and to determine the best model under a free-floating regime. The combination of these factors, namely, the number of layers [double (D) and single (S)], geometry mode [3D and manual (M)], and layer type [massless (M) and no glazing window (W)], led to the development of five models: D_3D_M, D_3D_W, D_M_M, S_3D_W, and S_M_M. The simulation was performed in a standard radiation mode, and the output parameters were temperature and relative humidity (RH). R² and the root square mean error (RSME) were used to check the fitness and degree of deviation, respectively, to validate the models. Analysis of variance (ANOVA) was employed to investigate the significant difference among the models. In contrast, contour plots were used to compare the distribution pattern between the significant models and experimental data. Validation of the models showed that the obtained R² values ranged from 0.86 to 0.95, and the RSME values for the temperature were between 2.64℃ and 3.91℃. These values were 0.91-0.93 and 19.72%-30.32% for RH. The ANOVA (p < 0.05) result exhibited significant differences between the S-scenario models and experimental central points in temperature and RH. The D- and S-layer scenarios with a 3D geometry and massless layer exhibited similar distribution with their corresponding experimental greenhouses. Hence, 3D_M was regarded as the best combination in the discretized BES model.