• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.563-574
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• 2009

This paper briefly describes the fundamental strategies--path-tracing, pin-pointing, and path-switching--in the computational elastic bifurcation theory of geometrically non-linear single-load-parameter conservative elastic spatial structures. The stability points in the non-linear elasticity may be classified into limit points and bifurcation points. For the limit points, the path tracing scheme that successively computes the regular equilibrium points on the equilibrium path, and the pinpointing scheme that precisely locates the singular equilibrium points were sufficient for the computational stability analysis. For the bifurcation points, however, a specific procedure for path-switching was also necessary to detect the branching paths to be traced in the post-buckling region. After the introduction, a general theory of elastic stability based on the energy concept was given. Then path tracing, an indirect method of detecting multiple bifurcation points, and path switching strategies were described. Next, some numerical examples of bifurcation analysis were carried out for a trussed stardome, and a pin-supported plane circular arch was described. Finally, concluding remarks were given.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1694-1704
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• 2015

In this paper, a robust trajectory tracking control method of a wheeled mobile robot is newly proposed combining the PDC and the ISMC. The PDC is a relatively simple and easy control method for nonlinear system compared to the other non-linear control methods. And the ISMC can have robust and stable control characteristics against model uncertainties and disturbances from the initial time by placing the states on the sliding plane with desired nominal dynamics. Therefore, the proposed PDC+ISMC trajectory tracking control method shows robust trajectory tracking performance in spite of external disturbance. The tracking performance of the proposed method is verified through simulations. Even though the disturbance increases, the proposed method keeps the performance of the PDC method when there is no disturbance. However, the PDC trajectory tracking control method has increasing tracking error unlike the proposed method when the disturbance increases.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.29-32
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• 1996

기존의 안과 진단 및 치료 기기의 안구 고정장치는 진단 및 치료에 있어서 피검사자와 검사자에 사이에 충분한 협조가 되지 않을 경우 진단의 비효율성과 치료의 안정성등의 문제가 발생하고있다. 따라서 이러한 문제를 보완하기 위하여 SLO의 전면 세극등을 소형의 반사경으로 대치하고 표시등을 후면의 먼거리에 수직으로 배열시켜서 피검사자에게 적당한 높이의 고정등을 선택하게하여 수직방향의 안구 위치를 고정시키고 SLO(Scanning Laser Ophthalmoscope)의 좌우 회전기능으로 표적의 수평방향을 근절시킨 후에 검사자의 조작으로 원격조정되는 서보장치를 이용하여 다시 반사경을 전방향으로 미세하게 회전되게하여 정확한 위치로 안구를 이동시키게 하는 원격조정 표적 추적장치를 개발하였다. 이에 따라 피검사자는 거울에 비친 먼거리의 허상을 보게 되어 세극등을 이용한 근접주사방식의 단점인 안구의 축동, 폭주등으로 인한 환자의 눈의 피로를 최소화하면서 피검사자의 안구를 검사자가 원하는 위치로 고정시킬 수 있게 함으로써 임상실험에서 안과 진단의 정확성과 관리도를 높이고 치료의 효율성과 안전성을 증가시킬 수 있는 원격조정 추적장치로써의 성능을 확인하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.579-586
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• 2019

Pilot Point Method (PPM) is one of the popular methods to search hydraulic conductivities in the inverse method using groundwater flow equations. In this study, the Simultaneous Search based Pilot Point Method (SSBM) was applied with diverse information (e.g. hydraulic heads and/or tracer concentration) applications over previously developed sensitivity based Pilot Point Method (e.g. D-optimality based Pilot Point Method: DBM). In the case of DBM, due to the minimized the variance size, tracer concentration can be recognized as a tool to control the searching space of hydraulic conductivities. SSBM reduced the procedure of hydraulic conductivity searching, though it produced more variance for exploring hydraulic conductivities. In addition, SSBM was dependent on the initial hydraulic conductivity values for search finalized hydraulic conductivities. When tracer concentration was applied, searching hydraulic conductivities was more preferable than only when hydraulic head was applied. Applications of various data for searching hydraulic conductivities is recommended as a more efficient way.

• Korean Journal of Construction Engineering and Management
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• v.15 no.1
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• pp.3-10
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• 2014

High-rise buildings need thorough cost management because of large size and high risk. Cost management makes a budget by establishing and analyzing detail element at planning phase, needs cost control as each design phase, then reflected to next design. This research develops a schematic estimation model based on vertical and horizontal elements at design phase for structure cost of high-rise buildings to reduce error range and use data as design management. Usability of the model is confirmed by case study. The estimation model is expected to contribute to making the cost model more effective and satisfactory to concerned in construction or budget department and manage keeping track of the cost.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.2 no.2
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• pp.178-184
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• 1999

Purpose: The aims of this study were to evaluate the clinical manifestations and prognosis of the syndromic and nonsyndromic intrahepatic bile duct paucity (IHBDP). Methods: We studied histology of 42 infants with neonatal cholestasis. Fourteen patients were diagnosed as IHBDP. We evaluated the clinical manifestations, courses and prognosis retrospectively. Results: Underlying disease of the 42 infants with neonatal cholestasis were biliary atresia in 23, intrahepatic bile duct paucity in 14 (Alagille syndrome in 4 and nonsyndromic IHBDP in 10), neonatal hepatitis in 5 infants. The mean ratio of the bile ducts per portal tract was 0.087 (range: 0~0.5). The manifestations in 4 patients with Alagille syndrome demonstrated as follows: characteristic face in 3, chronic cholestasis in 4, posterior embryotoxon in 2, vertebral anomalies in 2, peripheral pulmonary stenosis in 2. One of 4 patients of Alagille syndrome improved cholestasis and the other 3 patients were remained their cholestasis and growth retardation. All patients of the nonsyndromic IHBDP were idiopathic. Seven out of 8 patients of nonsyndromic IHBDP showed improvement of cholestasis, and one patient received liver transplantation due to cirrhosis. Conclusion: This study suggested that IHBDP should be considered in the differential diagnosis of neonatal cholestasis. The outcome of idiopathic IHBDP was better than predicted.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10a
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• pp.475-478
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• 2006

실감형 게임은 사람의 신체 움직임 및 오감을 최대한 반영한 리얼리티를 추구하는 전문적인 게임이다. 현재 개발된 실감형 게임들은 비 장애우를 대상으로 만들어 졌기 때문에 많은 움직임을 필요로 한다. 하지만 신체적 불편함을 가진 장애우들은 이러한 게임들을 이용하는데 어려움이 있다. 따라서 본 논문에서는 PC상에서 최소의 얼굴 움직임을 사용하여 수행할 수 있는 실감형 게임 시스템을 제안한다. 제안된 실감형 게임 시스템은 웹 카메라로부터 얻어진 영상에서 신경망 기반의 텍스쳐 분류기를 이용하여 눈 영역을 추출한다. 추출된 눈 영역은 Mean-shift 알고리즘을 이용하여 실시간으로 추적되어지고, 그 결과로 마우스의 움직임이 제어된다. 구현된 flash게임과 연동하여 게임을 눈의 움직임으로 제어 할 수 있다. 제안된 시스템의 효율성을 검증하기 위하여 장애우와 비 장애우로 분류하여 성능을 평가 하였다. 그 결과 제안된 시스템이 보다 편리하고 친숙하게 신체 장애우 에게 활용 될 수 있으며 복잡한 환경에서도 확실한 얼굴 추적을 통하여 실감형 게임 시스템을 실행 할 수 있음이 증명되었다.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.2
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• pp.130-135
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• 2007

This paper deals with a controller design for a 2 dimensional aeroelatic model which has unknown parameters including polynomial type nonlinearity. Actually in case of state and acuator signal having magnitude, rate and bandwidth limitations, the controller can't be implemented and so in each case, a filter is used for implementation. First, error signals are defined upon the backstepping theory, and tracking error signals are also defined due to command signal and filter signals and then compensated tracking error signals are defined. Lastly, a Lyapunov function is defined for the stabilization and from this method, an adaptive law is derived. Simulations are done for the demonstrtion of the effectiveness of the algorithms.

• Informatization Policy
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• v.28 no.2
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• pp.3-33
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• 2021

The purpose of this study is to analyze the research trends in the field of Blockchain that is one of the core technologies of the 4^th Industry, and present future research orientation. In this study, (1) Blockchain technologies in business perspective are summarized; (2) analysis criteria of Blockchain fields are established; and (3) results of analysis are presented and future research orientation is proposed. Major findings are as follows: (1) related research is being activate with the advent of the 3rd generation blockchain which aims for distributed applications. (2) major concerns of the technology (engineering) field is blockchain scalability and of the business (application) field is blockchain-based supply chain traceability. (3) Compared to overseas, domestic research results are very poor. (4) to catchup the gap, the spreading of awareness that blockchain is not a technology but a business means is required.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.175-180
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• 2005

Incorrections between model and plant are parameter, system order uncertainties and modeling error due to disturbance like friction. Therefore to achieve a good tracking performance, adaptive discrete time sliding mode tracking controller is used under time-varying desired position. Based on the diophantine equation, a new discrete time sliding function is defined and utilized for the control law. Robustness is increased by using both a recursive least-square method and a sliding function-based nonlinear feedback. The effectiveness of the proposed control algorithm is proved by the results of simulation and experiment.