• 자원환경지질
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• 제28권1호
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• pp.79-88
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• 1995

The gravity measurment has been carried out at 48 gravity stations with intervals of 1.0~1.5 km along the survey line between Samcheog, Gosari and Taebaek to study subsurface geology and geologic structure in the northeastern part of the Ockchon zone. The Bouguer gravity anomaly values were obtained from the measured gravity values through the gravity corrections. The subsurface geology and geologic structure were interpreted quantitatively by means of the Fourier series method and Talwani method for 2.5 dimensional body. In the study area, the depth of Conrad discontinuity is about 10 km at Samcheog, northeastern end of the survey line, and it is increased rapidly to about 12.5 km at Miro, 15 km at Gosari and 15.5 km at Dongjeom, southwestern end of the survey line, respectively. The depth of the basement of the Ockchon zone exposed at Samcheog is increased smoothly to about 2 km at 5 km from Samcheog along the survey line, and is exposed again in the area between Singiry and Gosari. Beyond Gosari its depth is increased to about 1.7 km, and displaced 2.3 km downward by Osipcheon fault near Dogyeri and 0.5 km by Baeksan thrust near Cheolam, respectively. Many V-shaped low Bouguer gravity anomalies resulted from the fracture zone associated with faults imply the existence of Osipcheon fault and several inferred faults. The low Bouguer gravity anomaly zone between Tongdong and Dongjeom is caused by Jurassic gneissose granite. A local high Bouguer gravity anomaly at 35 km along the survey line from Samcheog is interpreted by the effect of iron deposit of high density existed at subsurface. The thickness of Great Limestone Group varies from 0.5 km to 1.4 km, that of Pyeongan Supergroup from 0.4 km to 0.9 km, and that of Yangdeog Group is about 0.3 km. The thickness of Jurassic gneissose granite varies from 1.5 to 3.0 km.

• 한국산학기술학회논문지
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• 제17권12호
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• pp.686-691
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• 2016

용접강구조물에서는 용접비드와 같은 응력집중부가 많이 존재한다. 또한 용접부에서는 용접결함이 발생할 가능성이 많다. 반복적인 피로하중이 응력집중부에 작용하면 응력집중부에서 피로균열이 발생하고, 발생된 균열의 전파에 의해 피로파괴사고를 일으킨다. 따라서 피로파괴사고를 미연에 방지하기 위하여 균열발생수명과 균열전파수명과 같은 피로수명의 파악이 필요하다. 본 연구에서는 피로균열전파특성 연구에 사용되는 컴플라이언스를 도출하였다. 이 컴플라이언스는 피로균열의 자동화 측정에 활용할 수 있다. 본 연구에서는 CT시험편에 대하여 in-house FEM program을 사용하여 컴플라이언스를 계산하였다. 이 계산결과는 저자의 앞선 연구에서 본 프로그램을 사용하여 계산한 J integral의 계산결과와 대비하여 a/W와의 관계를 제시하였다. 그리고 또한 CT시험편 Back Face의 중앙부로부터 위아래 방향의 스트레인 분포에 계산을 실시하였다. 이 분포에서는 중심으로부터 위아래로 갈수록 스트레인이 감소하는 경향을 나타내었다. 이상의 계산과정으로부터 균열진전시험의 자동수행을 위한 컴플라이언스를 얻을 수 있었다. 이것으로부터 CT 시험편의 피로균열진전시험의 자동화에 활용이 가능하게 되었다.

• 한국인터넷방송통신학회논문지
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• 제12권3호
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• pp.29-35
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• 2012

본 논문에서는 MPEG(Moving Picture Experts Group) 영상 디코더에서 영상을 압축, 비교, 복원, 저장한후 디코딩 처리하는 방법을 종래의 픽셀 단위로 처리하는 방법과는 다르게 영상의 단위 화소 주변을 군집화소로 분류한 후 이를 클러스터링하여 오버랩정도를 결정 한다. 오버랩 정도의 임계치값을 결정하는데는 패턴식별을 취한후 샘플 패턴에 대한 기하구조의 파악과 결정함수의 도출로 활용된다. 특징공간이 4차원 이상이면 주어진 패턴 구조를 시각적으로 관찰할 수 없다. 이 때, 분포구조를 고찰해 볼수 있는 방법은 군집중심간의 거리, 군집별 패턴의 수 및 표준편차 등을 이용하는 방법이다. 임계치 값을 넘는 중복화면은 소거되고 넘지않는 군집화면은 패턴인식으로 복원된후 동영상으로 구현된다. 이방법이 기존의 픽셀 단위 처리하는 방법 과는 20%정도의 메모리 감축과 15%정도의 화면 복원에 성능이 향상된 것으로 판정된다.

• 한국항공우주학회지
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• 제35권1호
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• pp.18-26
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• 2007

날개들이 편대를 이루면서 비행하는 경우의 정상상태 공력특성에 대하여 와류격자법을 이용하여 해석하였다. 2개의 날개가 편대 비행 상태에 있을 때, 선도 날개에 의하여 후방 날개의 부분 양력계수가 높아짐을 알 수 있었다. 3개 이상의 날개를 일렬 및 V자편대 배치하여 양항비에 대하여 해석하였는데, 날개가 편대의 후방에 위치할수록 커지고, 가로 간격이 벌어질수록 작아짐을 알 수 있었다. 가로세로비가 증가할수록 전방 날개와 후방 날개의 양항비 차이가 커짐을 알 수 있었다. 후방 날개의 높이를 변화시켰을 경우, 같은 높이에서 최대 양항비를 나타내었다. 3개, 9개, 15개의 날개를 편대 비행했을 경우 날개 수가 많아질수록 편대 비행의 이득이 증가함을 알 수 있었다.

• 한국항공우주학회지
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• 제41권10호
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• pp.761-769
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• 2013

헬리콥터의 후류가 공기력에 미치는 영향은 매우 크다. 하지만 후류의 형상은 매우 복잡하며 예상하기 힘들다. 본 연구에서는 수치적인 방법을 통하여 후류를 자세히 관찰할 것이다. 후류에서의 와류를 자세히 관찰하기 위한 수치적 방법으로는 와류격자법과 자유후류법을 사용하였다. 본 연구에서 제자리 비행에서의 후류 형상을 관찰하였다. 적절한 추력계수를 갖는 제자리 비행에서는 익단 와류 뿐 아니라 블레이드의 안쪽에서 발생하는 counter-rotating vortex도 관찰할 수 있다. 이러한 와류들이 아래로 내려가면서 익단 와류와 counter-rotating vortex가 서로 가까워지며 서로에게 영향을 끼치게 된다. 이에 따라 와류들은 자체적인 불안정성으로 인해 형상이 변한다.

• 대한치과보철학회지
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• 제36권2호
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• pp.293-301
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• 1998

The purpose of this study was to investigate the effects of load on root that was applied to edentulous area in three simulated situation, in each case the guiding planes of abutment were right vertical, 95 degrees, or 100 degrees to residual ridge. The 2-dimensional finite element method was used and the finite element model was prepared as fellows. Right mandibular 1st and 2nd molar was lost and the 2nd premolar with distal rest was used as primary abutment which had three different degrees of guiding plane. Then 150N of compressive force was applied to central fossae of the 1st and 2nd molars and von Mises stress and displacement was measured. The results were as follows; 1. Irrespective of slopes of guiding planes, the stress was concentrated on mesial side of root apex and distal side of coronal portion of root, in particular on junction with distal alveolar bone. As slopes of guiding planes were increased. stress on root and compact bone surrounding abutment was increased but no considerable effect was seen on compact bone of residual ridge. 2. Distal side of coronal portion of root limited by periodontal ligament was displaced distally and mesial side of apical portion was mesially. With slope of guiding plane increasing, the pattern of displacement was similar with one another but the quantity was increased. 3. Both abutment & alveolar bone were displaced downward and root of abutment, especially distal side of coronal portion, was displaced severely. As the guiding plane was tiffed more mesially over $90^{\circ}$, the degree of displacement was also increased.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.285-286
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• 1998

Virtual Brain-endoscopy is an effective method to detect lesion in brain. Brain is the most part of the human and is not easy part to operate so that reconstructing in 3D may be very helpful to doctors. In this paper, it is suggested that to increase the reliability, method of matching 3D object with the 2D CT slice. 3D Brain-endoscopy is reconstructed with 35 slices of 2D CT images. There is a plate in 3D brain-endoscopy so as to drag upward or downward to match the relevant 2D CT image. Relevant CT image guides the user to recognize the exact part he or she is investigating. VRML Script is used to make the change in images and PlaneSensor node is used to transmit the y coordinate value with the CT image. The result is test on the PC which has the following spec. 400MHz Clock-speed, 512MB ram, and FireGL 3000 3D accelerator is set up. The VRML file size is 3.83MB. There was no delay in controlling the 3D world and no collision in changing the CT images. This brain-endoscopy can be also put to practical use on medical education through internet.

• 응용통계연구
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• 제29권1호
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• pp.99-112
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• 2016

비대칭 점프확산 모형은 자산 가격의 비대칭적 변동을 효과적으로 설명하는 모형으로 활용되어 왔다. 그러나 다변량 모형으로 확장한 다변량 비대칭 라플라스 점프확산 모형은 가능도함수가 닫힌 해로 존재하지 않아 모형의 추론에 한계가 존재하였다. 본 논문에서는 이러한 한계점을 극복하기 위해 자료 확장 기법을 제안하고 새로운 베이지안 추론 방법을 개발한다. 본 논문에서 제안된 모형은 단일 점프와 공통 점프 뿐만 아니라 모든 가능한 조합으로 발생하는 점프를 반영한 확장된 다변량 비대칭 라플라스 점프확산 모형이다. 이러한 모형을 분석하기 위해 붕괴된 깁스 샘플러를 고안한 베이지안 방법을 개발하였다. 본 논문에서 제안된 모형과 방법을 모의실험 자료 및 2005년 1월 3일부터 2015년 9월 30일까지 관찰된 일별 KOSPI, S&P500, 그리고 Nikkei225에 적용하여 효율성을 검증하였다.

• 산업경영시스템학회지
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• 제40권2호
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• pp.51-59
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• 2017

Due to the rapid change of global business environment, the growth of China's steel industry and the inflow of cheap products, domestic steel industry is faced on downward trend. The change of business paradigms from a quantitative growth to a qualitative product is needed in this steel industry. In this environment, it is very important for domestic steel distribution companies to secure their competitiveness by selecting good supply companies through a efficient procurement strategy and effective method. This study tried to find out the success factors of steel distribution industry based on survey research from experts. Weighted values of each factors were found by using AHP (analytic hierarchy process) analysis. The weighted values were applied to DEA(data envelopment analysis) model and eventually the best steel supply company were selected. This paper used 29 domestic steel distribution firms for case example and 5 steps of decision process to select good vendors were suggested. This study used quality, price, delivery and finance as a selection criteria. Using this four criterions, nine variable were suggested. Which were product diversity, base price, discount, payment position, average delivery date, urgency order responsibility and financial condition. These variables were used as a output variable of DEA. Sales and facilities were used as an input variable. Pairwise comparison was conducted using these variables. The weighted value calculated by AHP pairwise comparison were used for DEA analysis. Through the analysis of DEA efficiency process, good DMU (decision making unit) were recommended as a steel supply company. The domestic case example was used to show the effectiveness of this study.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.247-252
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• 2009

The LMC method of construction which have application to the road bridge is being considered the least relative importance about the watertight performance, because it focused on the durability of concrete. However, The LMC which is being expanded scope of application to the method of construction has grown importance about the watertight performance on the usability and maintenance side as well as durability. In this study, The latex concrete of two types which are different from mingled-ratio of the latex made a comparison to the compressive strength, watertight performance, dynamic wheel load resistance performance and confirmed what it has resistibility about chemical action through the chemical resistance test. The initial strength and watertight performance showed that were tendency the downward at 14 days. However, The long-term strength after 28 days showed that it has firm performance. In consequence, The initial curing of latex concrete is required to scrupulous care and attention at the site application. As a chemical resistance test result, The specimen that is steeped in sulphuric acid solution of 2% discovered the delamination phenomenon. However, it was confirmed that delamination phenomenon don't have an effect on the compressive strength. Moreover, As a dynamic wheel load resistance test result, The latex concrete was concluded to confirming the durability and running stability, because it had hardly any thickness reduction of latex concrete surface about dynamic wheel load and rarely found crack and delamination.