• 설비공학논문집
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• 제21권12호
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• pp.715-732
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• 2009

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2008. 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 in thermal and fluid engineering have been surveyed in the categories of general fluid flow, fluid machinery and piping, new and renewable energy, and fire. Well-developed CFD technologies were widely applied in developing facilities and their systems. New research topics include fire, fuel cell, and solar energy. Research was mainly focused on flow distribution and optimization in the fields of fluid machinery and piping. Topics related to the development of fans and compressors had been popular, but were no longer investigated widely. Research papers on micro heat exchangers using nanofluids and micro pumps were also not presented during this period. There were some studies on thermal reliability and performance in the fields of new and renewable energy. Numerical simulations of smoke ventilation and the spread of fire were the main topics in the field of fire. (2) Research works on heat transfer presented in 2008 have been reviewed in the categories of heat transfer characteristics, industrial heat exchangers, and ground heat exchangers. Research on heat transfer characteristics included thermal transport in cryogenic vessels, dish solar collectors, radiative thermal reflectors, variable conductance heat pipes, and flow condensation and evaporation of refrigerants. In the area of industrial heat exchangers, examined are research on micro-channel plate heat exchangers, liquid cooled cold plates, fin-tube heat exchangers, and frost behavior of heat exchanger fins. Measurements on ground thermal conductivity and on the thermal diffusion characteristics of ground heat exchangers were reported. (3) In the field of refrigeration, many studies were presented on simultaneous heating and cooling heat pump systems. Switching between various operation modes and optimizing the refrigerant charge were considered in this research. Studies of heat pump systems using unutilized energy sources such as sewage water and river water were reported. Evaporative cooling was studied both theoretically and experimentally as a potential alternative to the conventional methods. (4) Research papers on building facilities have been reviewed and divided into studies on heat and cold sources, air conditioning and air cleaning, ventilation, automatic control of heat sources with piping systems, and sound reduction in hydraulic turbine dynamo rooms. In particular, considered were efficient and effective uses of energy resulting in reduced environmental pollution and operating costs. (5) In the field of building environments, many studies focused on health and comfort. Ventilation. system performance was considered to be important in improving indoor air conditions. Due to high oil prices, various tests were planned to examine building energy consumption and to cut life cycle costs.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.8-9
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• 2017

Soybean yield has been low and unstable in Japan and other areas in East Asia, despite long history of cultivation. This is contrasting with consistent increase of yield in North and South America. This presentation tries to describe perspective of breaking stagnation of soybean yield in East Asia, considering the factors of the different yields between regions. Large amount of rainfall with occasional dry-spell in the summer is a nature of monsoon climate and as frequently stated excess water is the factor of low and unstable soybean yield. For example, there exists a great deal of field-to-field variation in yield of 'Tanbaguro' soybean, which is reputed for high market value and thus cultivated intensively and this results in low average yield. According to our field survey, a major portion of yield variation occurs in early growth period. Soybean production on drained paddy fields is also vulnerable to drought stress after flowering. An analysis at the above study site demonstrated a substantial field-to-field variation of canopy transpiration activity in the mid-summer, but the variation of pod-set was not as large as that of early growth. As frequently mentioned by the contest winners of good practice farming, avoidance of excess water problem in the early growth period is of greatest importance. A series of technological development took place in Japan in crop management for stable crop establishment and growth, that includes seed-bed preparation with ridge and/or chisel ploughing, adjustment of seed moisture content, seed treatment with mancozeb+metalaxyl and the water table control system, FOEAS. A unique success is seen in the tidal swamp area in South Sumatra with the Saturated Soil Culture (SSC), which is for managing acidity problem of pyrite soils. In 2016, an average yield of $2.4tha^{-1}$ was recorded for a 450 ha area with SSC (Ghulamahdi 2017, personal communication). This is a sort of raised bed culture and thus the moisture condition is kept markedly stable during growth period. For genetic control, too, many attempts are on-going for better emergence and plant growth after emergence under excess water. There seems to exist two aspects of excess water resistance, one related to phytophthora resistance and the other with better growth under excess water. The improvement for the latter is particularly challenging and genomic approach is expected to be effectively utilized. The crop model simulation would estimate/evaluate the impact of environmental and genetic factors. But comprehensive crop models for soybean are mainly for cultivations on upland fields and crop response to excess water is not fully accounted for. A soybean model for production on drained paddy fields under monsoon climate is demanded to coordinate technological development under changing climate. We recently recognized that the yield potential of recent US cultivars is greater than that of Japanese cultivars and this also may be responsible for different yield trends. Cultivar comparisons proved that higher yields are associated with greater biomass production specifically during early seed filling, in which high and well sustained activity of leaf gas exchange is related. In fact, the leaf stomatal conductance is considered to have been improved during last a couple of decades in the USA through selections for high yield in several crop species. It is suspected that priority to product quality of soybean as food crop, especially large seed size in Japan, did not allow efficient improvement of productivity. We also recently found a substantial variation of yielding performance under an environment of Indonesia among divergent cultivars from tropical and temperate regions through in a part biomass productivity. Gas exchange activity again seems to be involved. Unlike in North America where transpiration adjustment is considered necessary to avoid terminal drought, under the monsoon climate with wet summer plants with higher activity of gas exchange than current level might be advantageous. In order to explore higher or better-adjusted canopy function, the methodological development is demanded for canopy-level evaluation of transpiration activity. The stagnation of soybean yield would be broken through controlling variable water environment and breeding efforts to improve the quality-oriented cultivars for stable and high yield.

• 대한원격탐사학회지
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• 제38권5_3호
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• pp.939-951
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• 2022

자율주행차에 있어 가장 중요한 요소는 차량 주변 환경과 정확한 위치를 인식하는 것이며, 이를 위해 다양한 센서와 항법 시스템 등이 활용된다. 하지만 센서와 항법 시스템의 한계와 오차로 인해 차량 주변 환경과 위치 인식에 어려움이 있다. 이러한 한계를 극복하고 안전하고 편리한 자율주행을 위해서 고정밀의 인프라 정보를 제공하는 정밀도로지도(high definition map, HD map)의 필요성은 증대되고 있다. 정밀도로지도는 모바일 매핑 시스템(mobile mapping system, MMS)을 통해 획득된 3차원 point cloud 데이터를 이용하여 작성된다. 하지만 정밀도로지도 작성에 많은 양의 점을 필요로 하고 작성 항목이 많아 수작업이 요구되어 많은 비용과 시간이 소요된다. 본 연구는 정밀도로지도의 필수 요소인 차선을 포함한 도로, 연석, 보도, 중앙분리대, 기타 6개의 클래스로 MMS point cloud 데이터를 유의미한정보로 분할하여 정밀도로지도의 효율적인 작성에 목적을 둔다. 분할에는 머신러닝 모델인 random forest (RF), support vector machine (SVM), k-nearest neighbor (KNN) 그리고 gradient boosting machine (GBM)을 사용하였고 MMS point cloud 데이터의 기하학적, 색상, 강도 특성과 차선 분할을 위해 추가한 도로 설계적 특성을 고려하여 11개의 변수를 선정하였다. 부산광역시 미남역 일대 5차선도로 130 m 구간의 MMS point cloud 데이터를 사용하였으며, 분할 결과 각 모델의 평균 F1 score는 RF 95.43%, SVM 92.1%, GBM 91.05%, KNN 82.63%로 나타났다. 가장 좋은 분할 성능을 보인 모델은 RF이며 클래스 별 F1 score는 도로, 보도, 연석, 중앙분리대, 차선에서 F1 score가 각각 99.3%, 95.5%, 94.5%, 93.5%, 90.1% 로 나타났다. RF 모델의 변수 중요도 결과는 본 연구에서 추가한 도로 설계적 특성의 변수 XY dist., Z dist. 모두 mean decrease accuracy (MDA), mean decrease gini (MDG)가 높게 나타났다. 이는 도로 설계적 특성을 고려한 변수가 차선을 포함한 여러 클래스 분할에 중요하게 작용하였음을 뜻한다. 본 연구를 통해 MMS point cloud를 머신러닝 기반으로 차선을 포함한 여러 클래스로 분할 가능성을 확인하고 정밀도로지도 작성 시 수작업으로 인한 비용과 시간 소모를 줄이는데 도움이 될 것으로 기대한다.

• 한국환경생태학회지
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• 제38권4호
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• pp.388-404
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• 2024

국가 수준에서의 식물다양성보전의 대상은 제한적인 분포를 나타내는 특산식물이다. 본 연구에서는 한국특산식물인 동강할미꽃의 분포 현황을 조사하고 평가하였다. 다음으로 생육지의 식생환경을 조사하였고 각 개체군의 구조를 평가하였다. 이와 더불어 각 개체군의 활력을 평가하고 비교하였다. 추가적으로 연간생장특성을 관찰하였다. 동강할미꽃의 분포지는 크게 석회암 바위절벽, 능선 바위지대, 석회암지대의 산지 정상부 및 풍화작용에 의해 형성된 사질토양의 생육지로 구분되었다. 함께 분포하는 식물은 지리적인 위치에 따라 구분되었고 각각의 생육지를 반영하였다. 측정된 식물체의 잎 수를 이용하여 평가한 개체군 구조는 안정적인 개체군과 상대적으로 불안정한 개체군이 구분되었다. 상대적으로 어린 개체로 구성된 개체군은 능선 바위지대와 석회암지대의 산지 정상부 및 풍화작용에 의해 형성된 사질토양의 생육지에서 관찰되었다. 석회암 바위절벽의 개체군에서 성숙한 개체의 꽃 수가 가장 많았다. 반면에 석회암 산지의 정상부에 위치한 개체군은 잎 수는 많았지만 식물체의 키가 작고 화서의 수도 가장 적었다. 석회암 지대의 바위절벽에 분포하는 개체는 정착 이후 오랜 기간 동안 생육하면서 종자를 생산하고 확산시킨다고 판단되었다. 반면에 석회암 능선의 분포지와 석회암지대의 산지 정상부 및 풍화작용에 의해 형성된 사질토양의 생육지에서는 환경적인 요인으로 개체의 생장이 제한되었고 석회암의 절벽 분포지에 비해 상대적으로 짧은 생활사 주기를 나타내는 것으로 추정되었다. 동강할미꽃은 이른 봄철에 개화하고 여름철이 시작되기 이전에 열매 성숙과 종자 확산이 완성되었다. 생육지는 여름철을 기준으로 하루 중 7시간 내외로 햇볕을 받는 공간으로 평가되었다. 이것은 생장을 위해 강한 햇볕을 필요로 하는 동강할미꽃이 건조한 조건에서 정착하고 생존하여 생활사를 만들 수 있는 조건으로 생각되었다. 본 연구를 통해 확보된 현황 자료를 바탕으로 동강할미꽃은 위기종(EN)으로 평가하는 것이 타당하다고 평가되었다. 또한 수집된 정보는 향후 IUCN의 국가적색목록평가를 위한 중요한 정보가 될 것으로 예상되었다. 동강할미꽃은 강원도 평창군, 정선군의 석회암 바위 절벽에서 다양한 형질의 개체가 관찰됨에 따라 핵심적인 분포지로 높은 가치를 나타냄을 제안하였다.