• Geosystem Engineering
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• 제21권6호
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• pp.309-317
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• 2018

We employ a three-dimensional indirect boundary element method (BEM) to simulate temperature change around an underground liquefied natural gas storage cavern. The indirect BEM (IBEM) uses fictitious heat source strength on boundary elements as basic variables which are solved from equations of boundary conditions and then used to compute the temperature change at other points in the considered problem domain. The IBEM requires evaluation of singular integration for temperature change due to heat conduction from a constant heat source on a planar (triangular) region. The singularity can be eliminated by a semi-analytical integration scheme. However, it is found that the semi-analytical integration scheme yields sharp temperature gradient for points close to vertices of triangle. This affects the accuracy of heat flux, if they are evaluated by finite difference method at these points. This difficulty can be overcome by a combination of using a direct numerical integration for these points and the semi-analytical scheme for other points distance away from the vertices. The IBEM and the hybrid integration scheme have been verified with an analytic solution and then used to the application of the underground storage.

• 제어로봇시스템학회논문지
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• 제7권3호
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• pp.269-275
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• 2001

In land navigation applications, two kinds of GPS/DR integration schemes are commonly used; the loosely-coupled integration scheme and the tightly-coupled one. The loosely-coupled integration filter has a simple structure and is easy to implement. When the number of visible satellites is insufficient, however, it cannot calibrate the errors of the DR sensors. On the contrary the tigthly-coupled integration filter can sup-press the growth of the error in the DR output even when the visibility is poor. However, it has larger com-putation load due to the state dimension and is inconsistent because of the variation in the measurement dimension. This paper presents a GPS/DR integration scheme with dual integration mode. During when the number of visible satellites is sufficient, the proposed scheme operates in a loosely-coupled integration mode. When the visibility becomes poor, it is switched into a tightly-coupled integration mode. Consequently, the pro-posed scheme can calibrate the DR sensors even when the visibility is poor. In addition, its computation time remains constant even if the number of visible satellites increases. Field experiment results show that the performance of the proposed integration method is almost similar to that of the tightly-coupled one.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.986-998
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• 2003

In this paper, an adaptive numerical integration scheme, which does not need non-overlapping and contiguous integration meshes, is proposed for the MLPG (Meshless Local Petrov-Galerkin) method. In the proposed algorithm, the integration points are located between the neighboring nodes to properly consider the irregular nodal distribution, and the nodal points are also included as integration points. For numerical integration without well-defined meshes, the Shepard shape function is adopted to approximate the integrand in the local symmetric weak form, by the values of the integrand at the integration points. This procedure makes it possible to integrate the local symmetric weak form without any integration meshes (non-overlapping and contiguous integration domains). The convergence tests are performed, to investigate the present scheme and several numerical examples are analyzed by using the proposed scheme.

• 현장농수산연구지
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• 제25권2호
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• pp.20-29
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• 2023

This study suggests integration scheme for agricultural governance of South and North Korea after unification by comparing and analyzing their current agricultural governance, assuming drastic changes of economic system in integration process after unification. The North Korea's critical food shortage will force reformation of its agricultural governance to be the top priority in integration process after unification. The agricultural governance of South and North Korea has comparable structures. However, the North Korea's agricultural governance is extremely inefficient because it is established for political purposes. The integration scheme suggested includes expansion of Rural Development Administration, integration of research institutes, establishment of branch of Korea National University of Agriculture and Fisheries, transformation of existing North Korea's organization into South Korea's system and preparation of training programs for North Korea's officials.

• 한국통신학회논문지
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• 제30권5B호
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• pp.264-273
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• 2005

최근 들어 무선 네트워크 연동이 중요한 이슈로 부각되고 있으며, 대표적으로 3G 네트워크와 곧 도입될 예정인 WiBro 네트워크와의 연동에 관심이 집중되고 있다. 3G-WiBro 연동망이 구성될 경우 사용자는 서비스 지역에 따라 최적의 서비스를 제공받을 수 있으며, 사업자는 망 구축 및 운용비용을 절감할 수 있기 때문이다. 이를 위해 본 논문에서는 3G-WiBro 연동망에서 고속 핸드오프 지원을 위한 효율적인 연동 구조 및 세부적인 연동 방안을 제안한다. 본 논문에서 제안한 Smoothly Coupled Integration 방안은 Loosely Coupled Integration 방안과 Tightly Coupled Integration 방안의 장점을 수용할 수 있으며, 아울러 3G 네트워크와 WiBro 네트워크가 개별적으로 동작하면서도 고속 핸드오프 지원을 통한 Seamless 서비스와 이동성을 제공할 수 있는 구조를 갖고 있다. 제안한 방안의 성능을 검증하기 위해 OPNET을 이용한 컴퓨터 시뮬레이션을 수행하였으며, 이를 통해 제안한 방안의 우수성이 검증되었다.

• 한국지반공학회지:지반
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• 제14권4호
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• pp.129-140
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• 1998

탄소성 유한 요소 해석은 기지의 변형률 증분에 대한 응력 적분을 필요로 하며, 탄소성 구성 모델의 경우 특별한 경우를 제외하고는 해석적인 응력 적분이 불가능하고 수치적인 방법을 필요로 한다. 이때 응력 수치 적분의 정확도가 비선형 유한요소해의 전체적인 정확도에 상당히 큰 영향을 미치게 된다. 본 연구에서는 탄소성 구성 관계의 응력 적분을 위하여 외연적 방법중의 하나로서 Sloan이 제안한 단계분할 절차를 보완하여 안정적이고 정착한 응력 수치 적분법을 제시하고자 한다. 수정 오일러 절차에 따른 오차 조절의 기본 개념은 그대로 사용하고 오차를 평가하는 기준에 응력 수준이 영향을 미치는 단점을 보완하여 응력 수준에 관계없는 안정적이고 정확한 수치 적분법을 제시하였으며, 그 결과의 신뢰성을 삼축시험모사를 이용하여 검증하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.453-458
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• 2004

This study proposes a new two-level condensation scheme for the construction of a reduced system. In the first step, the candidate area is selected for the construction of the reduced system by energy estimation in element-level. In the second step, primary degrees of freedom are selected by sequential elimination from the candidate degrees of freedom linked to the selected elements. Numerical examples demonstrate that the proposed method saves the computational cost effectively and provides a reduced system which predicts the eigenvalues accurately. Moreover, the well-constructed reduced system can present the reliable behavior of the structure under arbitrary dynamic loads comparing to that of global system. Time integration in a reduced system can save the computing time remarkably. Through a few numerical examples, the efficiency and reliability of the proposed scheme are verified.

• Journal of Power Electronics
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• 제12권3호
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• pp.439-447
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• 2012

In this paper, an input-series auxiliary power supply scheme is proposed, which is suitable for high input voltage and multiple-output applications. The power supply scheme is based on a two-transistor forward topology, all of the series modules have a common duty ratio, all the switches are turned on and off simultaneously, and the whole circuit has a single power transformer. It does not require an additional controller but still achieves efficient input voltage sharing (IVS) for each series module through its inherent transformer-integration strategy. The IVS process of this power supply scheme is analyzed in detail and the design considerations for the related parameters are given. Finally, a 100W multiple-output auxiliary power supply prototype is built, and the experimental results verify the feasibility of the proposed scheme and the validity of the theoretical analysis.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2336-2347
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• 2018

The azeotrope of methyl acetate methanol and water was isolated using extractive distillation with water as entrainer. The pressure-swing extractive distillation (PSED) process and vapor side-stream distillation column (VSDC) with the rectifier process were designed to separate the methyl acetate, methanol and water mixture. It was revealed that the VSDC with the rectifier process had a reduction in energy consumption than the PSED process. Four control schemes of the two process were investigated: Double temperature control scheme (CS1), $Q_R/F$ feedforward control of reboiler duty scheme for PESD (CS2), $Q_R/F$ feedback control scheme for VSDC (CS3), the feedback control scheme of sensitive plate temperature of side-drawing distillation column to dominate the compressor shaft speed (CS4). Feed flow and composition disturbance were used to evaluate the dynamic performance. As a result, CS4 is a preferable choice for separation of methyl acetate-methanol-water mixture. A control scheme combining the operating parameters of dynamic equipment with the control indicators of static equipment was proposed in this paper. It means using the sensitive plate temperature of side-drawing column to control the compressor shaft speed. This is a new control scheme for extractive distillation.

• 대한감각통합치료학회지
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• 제7권1호
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• pp.47-57
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• 2009

목적: 본 논문에서는 감각통합치료프로그램이 발달장애아동의 신체도식과 실행능력에 어떠한 영향을 미치는가에 대하여 알아보았다. 연구방법: 30명의 발달장애아를 대상으로 6주 동안 Ayres의 감각통합이론을 근거로 변형된 발달장애아 감각통합 치료프로그램을 적용하여 실시하였다. 연구 대상자의 실행능력의 평가는 신체도식 검사(한점 모방 검사, 신체 6퍼즐 맞추기 검사), 실행검사(언어지시실행, 구강실행, 순서실행) 및 감각통합실행검사(SIPT)를 통하여 데이터를 수집하였으며 치료 전과 치료 후의 변화를 알아보기 위하여 대응표본 t-검정으로 통계처리 하였다. 결과: 1. 감각통합치료프로그램이 발달장애아의 신체도식능력, 즉 한 점 모방과 신체 6 퍼즐 맞추기 능력에서 치료 전 후에서 유의한 차이를 나타내었다(p<0.01). 2. 감각통합치료프로그램이 발달장애아의 실행능력, 즉 언어지시실행, 구강실행 과 순서실행 모두에서 치료 전 후에서 유의한 차이를 나타내었다(p<0.01). 3. 감각통합치료프로그램이 발달장애아의 감각통합실행능력(SIPT)에서 유의한 치료 효과를 나타내었다(p<0.01).