• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.555-562
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• 1998

Under the influence of non-uniform magnetic field, melt flow in steady state and oxygen concentration in unsteady state are numerically investigated. The strength of the applied characteristic magnetic fields are B=0.1T, 0.2T, and 0.3T, respectively. The buoyancy effects due to the crucible wall heating and the thermocapillary effects due to the surface tention at the free surface are suppressed differentially by the non-uniform magnetic fields. As the intensity of characteristic magnetic fields is increasing, the recirculation region in the meridional plane is moving toward the growing crystal, and is diminishing. The oxygen concentration on the growing surface of crystals is decreasing and the uniformity of the oxygen concentration is increasing as the intensity of the magnetic fields is increasing.

• Computational Structural Engineering
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• v.3 no.3
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• pp.101-111
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• 1990

The elastic analysis of floor slabs using the p-version of finite element method encounters stress singularities at certain types of reentrant corners, openings and cut-outs. Results obtained using the computer code based on C.deg. - hierarchic plate element formulated by Reissner-Mindlin theory are compared with theoretical predictions and with computational results reported in the literature. The convergence rate of h-, p- and hp-version can be estimated on the basis of the energy norm in global sense. If accuracy in terms of the number of degree-of-freedom is used as a criterion, the solutions presented here are the most efficient that have been published up to date. Examples are the rhombic plate with the obtuse angle of 150.deg. and the square plate with cut-outs.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.481-489
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• 2011

In this paper presents new force method by using singular value decomposition. The existing force method has some advantages about analysis of truss structures such as it is easier basic concept than finite element method, which apply to analyze truss structures. However, this method has complex formulation for analysis. Therefore, in this study proposes new force method using singular value decomposition, which is both having easy basic concept and simple computation than existing force method. The proposed method is illustrated through numerical examples.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.4
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• pp.125-134
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• 2015

In this paper, we present an algorithm based on particle filter to determine the state of human movement. We calculate speed from consecutive positioning data with time, latitude and longitude. The speed values are averaged with previous speed values and thus act as basis for particle filter. We use the fact that human speed distribution follows exponential distribution approximately. An algorithm based on particle filter has been developed and utilized. Human movement state are probabilistically described in this research, and the probability is to determine whether a person is in moving state or in stable state. The experimental results are provided in various ways.

• Journal of the Korean association of regional geographers
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• v.9 no.3
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• pp.385-394
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• 2003

Authors tried to classify landforms of civilian-restricted trans-border coastal region of the East Sea by using both field survey and remote sensing data including IKONOS images and digital maps. As a result, authors can draw the boundaries of landform units on satellite images and classify landforms effectively. Typical landforms of undisturbed depositional coastal area such as coastal sand dune, sand bar, lagoons, and tombolo are found within the study area. Also, riverine wetlands and estuarine wetlands are readily discernable on both satellite image and field survey. Even though landforms within the study area are relatively small, they are so dynamically connected that their preservation value is very high.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.4
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• pp.403-414
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• 1997

The distribution of the space debris caused by any source affects the DBS & FSS wave propagation for satellite communication. In this paper, the normalized expansion coefficients are evaluated with varying the volume distribution density of space debris and the operating frequency, and then the attenuation and phase shift are calculated by using the normalized expansion coefficients. Conclusively, the attenuation and phase shift are mostly affected with the real and imaginary part of the amplitude function, respectively, which represented by electric field component of the Bessel function. The results of this paper adapted for the design of the link budget for satellite communication system and the reconsideration of space environment as the space debris increses by geometric progression.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.81-88
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• 2005

This paper analyzes the fuel consumption for the momentum dumping of the COMS which has a single solar array system. First, numerical analyses are conducted to find an optimal momentum dumping time considering the COMS configuration. It is assumed that the momentum dumping is conducted once a day and at a fixed time of a day. Secondly, in an effort to reduce the momentum dumping fuel consumption, this paper proposes a new approach which combines the momentum dumping and the ordinary north/south stationkeeping. Finally, to evaluate the proposed technique, the stationkeeping simulations are conducted and analyzed.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.511-516
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• 2004

수치표고모델, 정사영상과 같은 공간영상정보를 구축하기 위해서는 입체영상을 이동한 영상정합(image matching)의 과정이 필수적이며, 단영상 또는 스테레오 영상을 이용하여 대상물의 3차원 정보를 재구성하고 복원하는 기술은 사진측량 및 컴퓨터 비전 분야의 주요 연구 중의 하나이다. 본 연구에서는 화소값의 유사성과 상호관계성을 고려하는 MRF 모델을 이용하여 영상정합을 수행하였다. MRF 모델은 공간분석이나 물리적 현상의 전후관계(contextural dependencies)의 분석을 위한 확률이론의 한 분야로 다양한 공간정보를 통합할 수 있는 방법을 제공한다. 본 연구에서는 기준영상의 화소에 시차를 할당하는 접근 방법으로 확률모델의 일종인 마르코프 랜덤필드(MRF)모델에 기반한 영상정합기법을 제안하였고, 공간내 화소의 상호관계를 고려해주므로 대상물의 경계부분에서의 매칭 정확도를 향상시켰다. 영상정합문제에서의 MRF 기본가정은 영상 내 특정화소의 시차는 그 주위화소의 시차에 의한 부분정보에 따라 결정이 가능하다는 것이다. 깁스분포(gibbs distribution)를 사용하여 사후(posteriori) 확률값을 유도해내고, 이를 최대사후확률(MAP: Maximum a Posteriori)추정법을 이용하여 에너지함수를 생성하였다. 생성된 에너지함수의 최적화(Optimization)를 위하여 본 연구에서는 전역최적화기법인 multiway cut 기법을 사용하여 영상정합에 있어 에너지함수를 최소로 하는 이미지화소에 대한 시차레이블을 구하여 영상정합을 수행하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.231-231
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• 2023

토양침식은 지표의 토양이 바람이나 물에 의해 분리되어 이송되는 자연현상이다. 우리나라에서는 주로 물에 의한 토양침식이 발생하며 특히 단기간 집중적으로 내리는 강우에 의해 토양침식이 일어난다. 토양의 침식현상은 농경지 유실, 하공구조물에서의 퇴적토 발생, 수질 오염등 다양한 문제를 일으키며 기후변화로 인한 집중강우의 빈도 및 강도 증가는 토양침식에 의한 피해를 증가 시키고 있다. 이러한 문제를 파악하기 위해 경험적 방법에 의해 개발된 범용토양유실공식인 USLE 모형이 널리 사용되고 있으나 연간 토양침식량을 산정하기 위해 개발된 USLE모형은 강우기간이 짧고 강우강도가 높은 집중호우와 같은 단기 강우사상을 모의할 수 없고 모든 지역을 표현하는 데 한계가 있다. 이에 따라 단기 강우사상을 고려할 수 있는 물리기반 침식모형인 SSEM모형을 활용하였다. SSEM모형은 운동파 방정식의 수치해석과 물리적 기반 접근방식을 통해 토양침식과정을 계산하여 집중호우로 인해 발생하는 토양침식을 보다 정확하게 추정할 수 있다. 이러한 모형의 적용성을 확인하기 위해 우리나라의 의암댐유역 선정하였으며, 지형 및 강우 그리고 댐자료 등 기초자료 수집과 수집된 데이터는 연구 대상에 대한 토양침식량 산정 및 매개변수 추정과 보정하는 데 사용되었다. 이 결과 다른 토지이용에 비해 농경지와 나지에서 많은 침식이 일어나며 도심지에서의 퇴적이 발생하였다.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.102-111
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• 2006

The increased occurrence of hyperglycemia and oxidative stress in streptozotocin (STZ) induced type I diabetes has been implicated in the etiology and pathology of disease complication. STZ has known to be genotoxic in a variety of assays including tests for microbial mutagenesis and unscheduled DNA synthesis in rat kidney. Diabetes mellitus (DM) is a pathologic condition, resulting in severe metabolic imbalances and non-physiologic changes in many tissues. We examined the effect of gamma radiation and KWNP on preventing the development of insulin dependent diabetes mellitus using streptozotocin-induced Fisher 344 diabetic rats. The hematological values (red blood cell and white blood cell), serum biochemical constituents-alkaline phosphatase (ALP), total cholesterol, triglycerides and insulin-were checked and the organs (testis, spleen and kidney) were weighed. The gonad indices of the STZ treated groups were much lower than the value of the control group. But the gonad indices of the KWNP treated groups were higher than those of the treated groups. The ratio of the weight of kidney to the body weight of the STZ treated groups was higher than that of the control group. The value of the diabetic group treated with KWNP after irradiation (F group) was lower than the other STZ treated groups. The white blood cell and ALP values of the F group were lower than the other STZ groups, as well. The cholesterol and triglyceride values of all the KWNP treated groups were significantly lower than the other groups. A significant increase (about 10 times) of insulin was detected in the F group. The results of hematological assay showed the distinctive damage in the irradiated and STZ treated groups. The quantity of apoptotic cells in seminiferous tubule of testis confirmed a serious damage as assessed in the STZ treated groups. These experimental results have revealed that treatment of the products of KWNP after irradiation has the antidiabetic effect in the STZ-induced diabetic rats. But the F group showed higher recuperative power. These experimental results have revealed that treatment of the gamma irradiation and KWNP have the recovering effect in the STZ-induced diabetic rats.