• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.6 no.1
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• pp.3-12
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• 1988

The objective of this paper is to study the characteristics of combination method to correct both angle and distance errors simultaneously based on the least square adjustment methods. Changing the standard errors of distance and angle, the simulation errors of triangultion, trilateration, and combination result in some 39.8%, 33.9%, and 26.3% respectively. As the above, combination method shows more consistent accuracy than other methods. When considering the weight factor about error elements with independence, the diminishing rate of simulated average standard error represents a various change in each method. But considering them simultaneously, it shows a remarkable rate of diminishing 75.5%, 74.1%, and 69.2% in each method. And also, by growing the weight factor, accuracy of triangulation method is growing, whereas that of trilateration is diminishing. Therefore, determining the reasonable weight factors of distance and angle errors simultaneously in the analytical combination method, this method is expected to be one of more accurate and more effective methods for determining horizontal positions on the earth.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.118-119
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• 2013

마리나 시설 내 계류된 선박 및 레저장비를 악천 후 해상상태와 선박 운항에 의해 발생된 파로부터 장비 및 인명의 안전을 위한 파 제거 장치가 필요하다. 본 연구에서는 국내 각 지자체의 수요에 부응하고 시설 및 인명의 안전을 위한 소파 시스템개발을 목적으로 시제품 제작(설계, 해석, 수조시험 등 수행완료)하였다. 실해상 성능시험에서 항주파의 발생을 위해 시험선박 선정하였으며, 소파장치 전후의 파고계측 등을 위해 부가물을 계측하여 파고를 촬영 및 계측하였다. 개발된 소파장치의 실해상 시험임을 감안해 해상 주위의 조류, 풍속, 인근 해역에서 오는 파랑변형 등에 따른 파랑요소를 고려하여 시험하였다. 부소파제는 약 40~80% 의 에너지 감소율을 보였으며, 유의파고 조건에서 42%의 에너지 감소율을 보였다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.127-133
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• 1991

Experiments were conducted to investigate the effect of light shading around the heading stage on grain yield and its components of rice. Early, medium, and late-maturing varieties were trected with the light shading of 50% and 75% from the reduction division stage to 20 days after heading date. Heading date were delayed 2-3 days, whereas the mid -late varieties, Sangpung- byeo, and Bongkwang- byeo were no significantly affected. Culm length was increased and panicle exsersion was reduced as the shading treatments become higher, and the degree of the shading effect was more intensive at 75% of shading. The rate of spikllet degeneration was higher at the secondary rachis branches than the primary rachis branch. The early maturing varieties showed the higher rate of spikelet degeneration. Spikelet number was reduced 12-15, spikelet sterility was increased and ripening rate was declined by the shading treatments. Grain yield was decreased by 30-40% at the shading treatment of 50%, and 50% at the shade treatment of 75%.

• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.497-508
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• 2006

This study was conducted to obtain the basic information on rice cold damage and relationship to be connected with cold tolerance. The 20 rice varieties were screened to cold tolerance under low water temperature condition. The water gradient were controlled to $17^{\circ}C$ at the inlet and $21^{\circ}C$ at outlet of screening field. In the relationship between cold water irrigation and growth of rice varieties, effect on medium maturing cultivars were higher than early maturing cultivars. In relationship of shorting of culm length and panicle exsertion, culm length and panicle exsertion showed positive correlation. Yield of cultivars and culm length and percent of fertile grain showed positive correlation. However, heading date presented negative correlation. In the early maturing cultivars, except 'Kumobyeo', all cultivars range of discoloration value (1-3) was resistant. In the medium maturing cultivars, 'Donghaebyeo' was resistant in both the seedling stage whereas 'Hwajinbyeo' was resistant only in tiller stage. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Unhulled rice yield was increased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.114-121
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• 1997

Latex Coated Urea(LCU) was compared with ordinary urea under different methods of application in terms of N use efficiency and yield of rice, 1995 and 1996. The study was carried out on Jeonbug silty clay loam, in Honam Agricultural Experiment Station. The fertilizer treatments involved (1) conventional application of urea (44kg N/ha at transplanting, 33kg N/ha at five leaves stage, 33kg N/ha. (4) 55kg N/ha at transplanting and 33kg N/ha as urea at panicle initiation stage, and (5) without N. It was found that by combining LCU(as basal application) and urea(as topdressing at panicle initiation stage), at the rate of 80% of conventional rate with ordinary urea is most effective for the saving of N and increasing the use efficiency of N by rice. It was, however, observed that the efficacy of LCU was affected by the temperature during the growth of rice.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.303-309
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• 2006

In this study, functional anion-exchange membranes have been prepared and characterized to improve the permeation fluxes of the anion and urea for peritoneum dialysis. They were prepared by UV and radiation graft polymerization methods. The separation-membrane prepared by UV graft polymerization showed the highest grafting degree when HEMA and VBTAC were mixed by 1:2 ratio. However, the grafting degree decreased slightly at compositions above the 1:2 ratio because of the disruption of UV penetration caused by build-up of homopolymer. In the case of photo-initiator, the grafting degree increased up to 0.2 wt%, above which it decreased to a small extent. For the two membranes prepared by radiation graft polymerization, the VBTAC/HEMA membrane showed 96% grafting degree for 6 h reaction time and the GMA membrane showed over 100% grafting degree for 2 h reaction time. Anion-exchange membranes were prepared with 113% grafting degree and with DEA and TEA exchange groups. The DEA membrane showed the conversion degree of 70% in 4 h reaction time while the TEA membrane showed 30% in 2 h reaction time. The prepared anion-exchange membranes were permeable to only anions and urea, but not cations.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.2
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• pp.53-69
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• 2020

The increase of the impermeable area due to industrialization and urban development distorts the hydrological circulation system and cause serious stream drying phenomena. In order to manage this, it is necessary to develop a technology for impact assessment of stream drying phenomena, which enables quantitative evaluation and prediction. In this study, the cause of streamflow reduction was assessed for dam and weir watersheds in the five major river basins of South Korea by using distributed hydrological model DrySAT-WFT (Drying Stream Assessment Tool and Water Flow Tracking) and GIS time series data. For the modeling, the 5 influencing factors of stream drying phenomena (soil erosion, forest growth, road-river disconnection, groundwater use, urban development) were selected and prepared as GIS-based time series spatial data from 1976 to 2015. The DrySAT-WFT was calibrated and validated from 2005 to 2015 at 8 multipurpose dam watershed (Chungju, Soyang, Andong, Imha, Hapcheon, Seomjin river, Juam, and Yongdam) and 4 gauging stations (Osucheon, Mihocheon, Maruek, and Chogang) respectively. The calibration results showed that the coefficient of determination (R²) was 0.76 in average (0.66 to 0.84) and the Nash-Sutcliffe model efficiency was 0.62 in average (0.52 to 0.72). Based on the 2010s (2006~2015) weather condition for the whole period, the streamflow impact was estimated by applying GIS data for each decade (1980s: 1976~1985, 1990s: 1986~1995, 2000s: 1996~2005, 2010s: 2006~2015). The results showed that the 2010s averaged-wet streamflow (Q95) showed decrease of 4.1~6.3%, the 2010s averaged-normal streamflow (Q185) showed decreased of 6.7~9.1% and the 2010s averaged-drought streamflow (Q355) showed decrease of 8.4~10.4% compared to 1980s streamflows respectively on the whole. During 1975~2015, the increase of groundwater use covered 40.5% contribution and the next was forest growth with 29.0% contribution among the 5 influencing factors.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2001.03a
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• pp.97-108
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• 2001

절리가 발달한 암반의 거동평가를 위한 해석적 방법은 연속체 모델과 불연속체 모델을 사용하는 방법으로 대별할 수 있으며, 연속체 모델을 사용할 경우에는 유한요소법이나 유한차분법을 이용하는 방법이 주종을 이루고 있다. 불연속체 모델은 개별 블록들의 움직임을 일일이 계산하므로 매우 매력적인 방법이지만 현재의 지반조사 기술수준으로는 지반내의 절리발달사항을 정확히 파악하기가 매우 어려우며, 컴퓨터의 계산용량이 너무 과다해지는 단점이 있다. 따라서, 불연속면을 포함한 암반을 연속체로 가정한 편재절리 모델(ubiquitous joint model)을 이용한 연구가 요구된다. 한편, 터널의 경우는 사면의 경우와는 달리 파괴면의 형상을 사전에 가정하기 어렵기 때문에 한계평형법에 기초한 해석법 등을 적용하여 안전율을 구하기가 곤란하다. 이러한 이유에서 터널을 대상으로 한 수치해석은 안전율을 구하기보다는 안정성을 평가하는 데만 제한적으로 사용되어 왔다. 본 논문에서는 편재절리모델을 이용한 절리암반터널의 거동 평가기법과 수치해석에 의해 터널의 안전율을 구하는 방법을 제시하는 데에 그 목적이 있다. 이를 위해 터널의 안전율 구하는 방법을 강도감소기법에 근거하여 제시하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1364-1365
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• 2008

가스 절연 개폐장치(Gas Insulated Switchgear)의 고체 스페이서에 다양한 유전율 분포를 가진 경사기능성 재료(Functionally Graded Material)를 적용할 때, 전계의 완화를 예상할 수 있다. FGM 스페이서는 전계의 집중을 완화시킬 수 있고, 내부의 전계를 더 균일하게 분포시킬 수 있다. 본 연구에서는 유한요소법을 이용하여 상용 GIS의 FGM 스페이서에서 전계의 세기를 계산하였다. 계산 결과를 통해 스페이서의 유전율이 빠르게 변화하는 경우, 더 효율적으로 최대전계를 감소시켰고, 스페이서 내부의 전계를 균일하게 하였다. 결과적으로 FGM 스페이서는 단일 유전율을 가진 스페이서에 비해 절연 성능을 향상시킬 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.887-890
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• 2003

본 논문에서는 현재 개발되고 있는 10Mbps급 전력선통신 모뎀이 일반 사용자의 환경에서 어떠한 성능을 보여주는 지를 살펴보기 위하여 다양한 노이즈 요소가 존재하는 실험실에 두 대의 모뎀을 설치하고서 RFC 2544에서 규정하고 있는 처리율, 셀 손실율, 그리고 지연시간 톡성을 분석하였다. 그 결과로서 프레임 사이즈가 커질수록, 즉 단위 시간당 프레임의 수가 감소할수록 높은 처리율과 낮은 지연 시간, 그리고 낮은 프레임 손실율을 보임을 알 수 있었다.