• Horticultural Science & Technology
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• v.33 no.5
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• pp.647-657
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• 2015

To investigate a method for calculation of the heating load for environmental designs of horticultural facilities, measurements of total heating load, infiltration rate, and floor heat flux in a large-scale plastic greenhouse were analyzed comparatively with the calculation results. Effects of ground heat exchange and infiltration loss on the greenhouse heating load were examined. The ranges of the indoor and outdoor temperatures were $13.3{\pm}1.2^{\circ}C$ and $-9.4{\sim}+7.2^{\circ}C$ respectively during the experimental period. It was confirmed that the outdoor temperatures were valid in the range of the design temperatures for the greenhouse heating design in Korea. Average infiltration rate of the experimental greenhouse measured by a gas tracer method was $0.245h^{-1}$. Applying a constant ventilation heat transfer coefficient to the covering area of the greenhouse was found to have a methodological problem in the case of various sizes of greenhouses. Thus, it was considered that the method of using the volume and the infiltration rate of greenhouses was reasonable for the infiltration loss. Floor heat flux measured in the center of the greenhouse tended to increase toward negative slightly according to the differences between indoor and outdoor temperature. By contrast, floor heat flux measured at the side of the greenhouse tended to increase greatly into plus according to the temperature differences. Based on the measured results, a new calculation method for ground heat exchange was developed by adopting the concept of heat loss through the perimeter of greenhouses. The developed method coincided closely with the experimental result. Average transmission heat loss was shown to be directly proportional to the differences between indoor and outdoor temperature, but the average overall heat transfer coefficient tended to decrease. Thus, in calculating the transmission heat loss, the overall heat transfer coefficient must be selected based on design conditions. The overall heat transfer coefficient of the experimental greenhouse averaged $2.73W{\cdot}m^{-2}{\cdot}C^{-1}$, which represents a 60% heat savings rate compared with plastic greenhouses with a single covering. The total heating load included, transmission heat loss of 84.7~95.4%, infiltration loss of 4.4~9.5%, and ground heat exchange of -0.2~+6.3%. The transmission heat loss accounted for larger proportions in groups with low differences between indoor and outdoor temperature, whereas infiltration heat loss played the larger role in groups with high temperature differences. Ground heat exchange could either heighten or lessen the heating load, depending on the difference between indoor and outdoor temperature. Therefore, the selection of a reference temperature difference is important. Since infiltration loss takes on greater importance than ground heat exchange, measures for lessening the infiltration loss are required to conserve energy.

• Korean journal of food and cookery science
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• v.28 no.4
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• pp.391-397
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• 2012

This study was carried out to investigate commercialization of Kimchi made of cabbage (Brassica oleracea var. capitata L.) using pre-fermentation conditions. The pre-fermentation conditions were 0, 18, 24, and 28 h at $20^{\circ}C$, and then the samples were stored at $10^{\circ}C$ to assess changes in quality characteristics. A comparison of the quality characteristics during storage showed that PF24 (pre-fermented cabbage Kimchi during 24 h at $20^{\circ}C$) and PF28 (pre-fermented cabbage Kimchi during 28 h at $20^{\circ}C$) had pH 4.47 and pH 4.23 on the second day of storage, respectively. It was possible to shorten the fermentation time to less than that of PF0 (not pre-fermented cabbage Kimchi at $20^{\circ}C$), by approximately 3 days. Total acidity was 0.26 to 0.29% immediately after making the Kimchi. However, PF0, PF18 (pre-fermented cabbage Kimchi during 18 h at $20^{\circ}C$), PF24 and PF28 became well-fermented when they were stored for 8~14 days, 3~10 days or 2~3 days. The number of lactic acid bacteria increased with the passage of time in all treatment groups regardless of fermentation conditions. However, the longer pre-fermentation time became, the faster the number of lactic acid bacteria increased. Most samples showed similar results late in the storage period; 7.2~7.4 log CFU/mL. PF0 had the greatest volume change 2.1 times increase late in the storage period. The sensory evaluation showed significant differences for flavor, taste, and overall acceptability after a partial storage period. PF28 stored for 2~3 days showed excellent flavor, and PF24 and PF28 stored for 2~3 days showed the highest scores of 6.27 to 6.67. The PF24 and PF28 treated samples were appropriate for commercializing small packed cabbage Kimchi and for alleviating the expansion problem of the packing material. However, because mass commercial production requires a large number of samples to be used at once, the results should be assessed for industrial product development in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.2
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• pp.183-193
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• 1995

Assuming that fishing nets are porous structures to suck water into their mouth and then filtrate water out of them, the flow resistance N of nets with wall area S under the velicity v was taken by $R=kSv^2$, and the coefficient k was derived as $$k=c\;Re^{-m}(\frac{S_n}{S_m})n(\frac{S_n}{S})$$ where $R_e$ is the Reynolds' number, $S_m$ the area of net mouth, $S_n$ the total area of net projected to the plane perpendicular to the water flow. Then, the propriety of the above equation and the values of c, m and n were investigated by the experimental results on plane nettings carried out hitherto. The value of c and m were fixed respectively by $240(kg\cdot sec^2/m^4)$ and 0.1 when the representative size on $R_e$ was taken by the ratio k of the volume of bars to the area of meshes, i. e., $$\lambda={\frac{\pi\;d^2}{21\;sin\;2\varphi}$$ where d is the diameter of bars, 21 the mesh size, and 2n the angle between two adjacent bars. The value of n was larger than 1.0 as 1.2 because the wakes occurring at the knots and bars increased the resistance by obstructing the filtration of water through the meshes. In case in which the influence of $R_e$ was negligible, the value of $cR_e\;^{-m}$ became a constant distinguished by the regions of the attack angle $ \theta$ of nettings to the water flow, i. e., 100$(kg\cdot sec^2/m^4)\;in\;45^{\circ}<\theta \leq90^{\circ}\;and\;100(S_m/S)^{0.6}\;(kg\cdot sec^2/m^4)\;in\;0^{\circ}<\theta \leq45^{\circ}$. Thus, the coefficient $k(kg\cdot sec^2/m^4)$ of plane nettings could be obtained by utilizing the above values with $S_m\;and\;S_n$ given respectively by $$S_m=S\;sin\theta$$ and $$S_n=\frac{d}{I}\;\cdot\;\frac{\sqrt{1-cos^2\varphi cos^2\theta}} {sin\varphi\;cos\varphi} \cdot S$$ But, on the occasion of $\theta=0^{\circ}$ k was decided by the roughness of netting surface and so expressed as $$k=9(\frac{d}{I\;cos\varphi})^{0.8}$$ In these results, however, the values of c and m were regarded to be not sufficiently exact because they were obtained from insufficient data and the actual nets had no use for k at $\theta=0^{\circ}$. Therefore, the exact expression of $k(kg\cdotsec^2/m^4)$, for actual nets could De made in the case of no influence of $R_e$ as follows; $$k=100(\frac{S_n}{S_m})^{1.2}\;(\frac{S_m}{S})\;.\;for\;45^{\circ}<\theta \leq90^{\circ}$$, $$k=100(\frac{S_n}{S_m})^{1.2}\;(\frac{S_m}{S})^{1.6}\;.\;for\;0^{\circ}<\theta \leq45^{\circ}$$

• (The)Study of the Eastern Classic
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• no.49
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• pp.73-107
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• 2012

Yeoheon Jang Hyeongwang(1554-1637), one of the greatest Mid-Joseon Confucianists did systematic studies on universe and nature. It can be considered that he inherited the academic tradition of Cho Sik (曺植) and Jeong Gu(鄭逑) and followed their steps of fengshui (風水) and compilation of geographical records. His living and thought and deserve researching with regard to geographical studies. This paper attempts to analyze Yeoheon's recognition of geography in general. In other words, I shall prove that his view of geography is Neo-Confucian. At the same time, I shall discuss how he named people's residence, how he understanded the Joseon territory, what he thought about fengshui, and what significance the complication of geographical records by his disciples had. Yeoheon considered that land is composed of water, fire, earth, and rock, and understanded the land according to the theory of Zhouyi (周易). He analyzed geographic environments by the system of Zhouyi. His study of geography is basically intended for practical use, and as a result is necessary for people to choose where to live and where to cultivate. In his opinion, it is essential to divide the land of the Joseon by means of geographical differences in order to help people to find a better place to live. We can see his Confucian view from the fact that he placed a greater emphasis on human beings over nature. Therefore, the practical use for humans is the first priority in his study of geography. Meanwhile, he considered nature itself as only the object of study. He realized the vitality of life by making a close observation of nature and attained the mind of the Heaven and Earth in a detached way. He, as a follower of Neo-Confucianism, enjoyed the land by feeling comfortable with his present status and by being satisfied with himself. He put his Confucian view of universe and world into practice in his life. As a part of his efforts, he named his residence and surrounding natural environments with the polar star and 28 stars, and accordingly they are reconstructed in a system of universe. The Confucian tradition of dongcheon gugok (洞天九曲) starting with Zhu Xi's administration of wuyi jiugu (武夷九曲) was widely prevalent during the Joseon period, but Yeoheon's system of organizing places is original. His sense of naming places reflects his ideas of following his predecessors, comparing natural objects to human emotions, and desiring to live in retirement. Yeoheon understanded the Joseon territory with comparison of the Chinese land. He expressed his knowledge in the form of changing geographical features of a district, appreciating natural beauty, locating towns, and being familiar with a region, and proposing his own climatology and view of the reality. His recognition of the Joseon territory resolves itself into the following several points. He regarded the Joseon territory as one organism, and considered the territory to be composed of ki (氣) as Neo-Confucianists usually do. In addition, he understanded not only natural environments but also towns from a perspective of the fengshui and adopted a comparative methodology in dividing regions. He also applied climatology to analyze persons and customs. He employed the methodology of fengshui from the comprehensive theory of the Yijing. It is because he was influenced by Cho Sik and Jeng Gu. Yeoheon chose dwelling places for people, or gave advice on several places of his hometown relying on his knowledge of fengshui. When it comes to his theory of fengshui, he agreed with the theory of topography with regards to the fengshui of tombs, but criticized the custom of delaying funerals in order to turn fortune in one's favor. In addition, he accepted that it is necessary to complement a town by creating forests around it. We need to pay attention to the fact that Yeoheon's disciples complied several geographical records. It proves that they inherited the tradition of "valuing practical use and governing on behalf of the people" from Cho Sik and Jeong Gu. Yeoheon put a great emphasis on geographical records and encouraged his disciples to compile them. In other words, he emphasized that they, as administrator or intellectual, need to be erudite in the history and custom of a region where they have lived, and have to establish a standard to encourage or warn people in the region while considering the geographical records. His opinion functioned as a guideline for his successors to compile geographical records later. This paper only analyzed several facts with regard to Yeoheon's knowledge of geography and an academic tradition concerning the study of geography. In the future, I shall discuss how his predecessors and successors understanded geography and how the tradition of compiling geographical records was transferred and developed between them. I believe that this study will contribute to establishing the history of geography, which the Joseon Confucianists researched for a long time but we have not paid an enough attention to until now.