• 대한화학회지
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• 제48권4호
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• pp.339-350
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• 2004

피코초 시간분해능 전자 회절 분광법(TRED)을 이용하여 $CClF_3$ 분자의평형 구조를 연구하였다. 이 분광법의 분해능은 전자파의 선폭에 의하여 결정된다. 본 연구 방법에 의하여 결정된 $CClF_3$ 분자의 결합 길이들을 고전적인 실시간 전자회절 분광법(GED/RT)에 의하여 보고된 결과들과 비교하였다. GED/RT 방법에 의하여 결정된 C-F 결합 길이와 C-Cl 결합 길이는 각각 132.00(2) pm, 175.20(3) pm이고, TRED 방법에 의하여 결정된 C-F, C-Cl 결합 길이는 각각 132.23(13) pm, 177.23(19) pm 로써 이 두 실험 방법에 의하여 결정된 분자 결합 길이는 좋은 일치성을 보여준다.

• 제어로봇시스템학회논문지
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• 제14권8호
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• pp.792-799
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• 2008

Motion estimation is crucial in a remote control for its convenience or accuracy. Time delays, however, can occur in the problem because data communication is required through a network. In this paper, state estimation problem with uncertain time delayed measurements is addressed. In dynamic system with noise, after taking measurements, it often requires some time until that is available in the filter algorithm. Standard filters not considering this time delays cannot be used since the current measurement is related with a past state. These delayed measurements are solved with augmented extended Kalman filter, and the uncertainty of delayed time is also resolved based on an explicit formulation. The proposed method is analyzed and verified by simulations.

• Korean Chemical Engineering Research
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• 제58권2호
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• pp.319-324
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• 2020

전기와류 불안정성은 전기투석 장치, 갈바니 전지, 전해 전지 등의 이온-선택성 이동 현상계에서 발견되는 비선형 이동 현상이다. 이 불안정성은 이온-선택성 표면 근처 공간 전하층의 요동에 의해 발생하며, 불안정성의 발현은 물질 전달 속도를 증가시켜 준다. 따라서 전기와류 불안정성은 물질 전달 측면에서 중요한 의미를 가진다. 최근의 실험적 기법들이 불안정성의 직접적 가시화를 가능하게 해주었으나, 실험적 한계점에 의해 불안정성의 원론적 연구는 제한된 영역에서만 이루어지고 있다. 본 연구에서는 일정 전위 모드에서의 전기와류 불안정성에 대한 수치 해석을 진행하여 전류-시간 곡선과 불안정성의 거동 간의 상관관계를 밝히고자 하였다. 시간-분해 해석을 통하여, 불안정성의 발달 거동을 SCL 형성 - 전기와류 불안정성의 성장 - 정상 상태 도달로 구분 지었다. 더불어, 인가 전위에 따른 전이 시간들의 크기 법칙 또한 수치적으로 유도하였다.

• Architectural research
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• 제25권2호
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• pp.29-40
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• 2023

The purpose of this study is to analyze the conflicts caused by the spatial expansion in two types of urban heritage in Seoul. To explain the national and professional orientation found in each spatial transformation, the study brought the concept of 'historic state' and 'epitome,' thereby examining the operating system of the conflicts. Field observations and stakeholder interviews were performed based on literature and historical research. The study results are as follows. ①In the case of Gwanghwamun and Donuimun, the spatial expansion is to find the historic state of the sites. Gwanghwamun with high national status and substance, conflicts show a pattern that spreads to memory conflicts. Donuimun is relatively unknown and has no substance so that a flexible method of digital restoration was applied. ② In the case of Ikseon-dong and Bukchon hanok, they show heterogeneous spatial expansion. The conflicts in relation to this is caused by the epitome of hanok. In Ikseon-dong, illegal installation of structures(non-epitome) is prevalent, while in Bukchon, there was a process of transferring the new basement(non-epitome) as part of the hanok. ③Conflicts in Gwanghwamun can be coordinated by referring to the digital restoration of Donuimun, and conflicts in Ikseon-dong can be resolved by taking Bukchon as a precedent.

• 한국주조공학회지
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• 제40권3호
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• pp.85-96
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• 2020

The effect of an aluminum scrap addition ratio on the tensile and solidification cracking properties of the AC4A aluminum alloy in the as-cast state and heat-treated state were investigated in this study. Generally, the expected problem of using scrap in aluminum casting is an increase of hydrogen and Fe element inside the aluminum melt. Another issue is an oxide film which has a weak interface with the molten aluminum and acts as potent nucleation sites for internal porosity and crack initiation. Solidification cracking is one of the critical defects that must be resolved to produce high quality castings. A conventional evaluation method for solidification cracking is a relative and qualitative analysis method which does not provide quantitative data on the thermal stress in the solidification process. Therefore, a newly designed solidification cracking test apparatus was used in this study, and the device can provide quantitative data. As a result, after conducting experiments with different scrap addition ratios (0%, 20%, 35%, 50%), the tensile strengths and elongations in the as-cast state were 214, 187.7, 182.1 and 170.4MPa and 4.6%, 3.4%, 3.1% and 2.3%, respectively. In the case of the T6 heat-treated state, the tensile strengths and elongations were 314.9, 294.6, 293.1 and 271.1MPa and 5.4%, 4.6%, 3.8% and 3.1%, respectively. The strength of the solidification cracking was 3.1, 2.4, 2.2and 1.6MPa as the scrap addition ratio increases.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제7권5호
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• pp.467-474
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• 2001

사용자가 하나의 캐릭터 이상을 애니메이션 하기를 원할때 캐릭터들 사이에 충돌과 같은 기대되지 않은 동작 애니메이션을 생성할 수 있다. 그러므로, 이러한 문제가 적절한 제어 메커니즘을 이용하여 해결되어야 한다. 본 논문은 사용자의 의도를 반영한 애니메이션 시나리오를 표현하기 위해 캐릭터의 동작 애니메이션을 제어하는 에이전트 기반 시스템을 제안한다. 이 시스템은 3차원 공간상에서 캐릭터가 움직이는 경로에 따라 캐릭터들간의 충돌을 회피하고 동작의 형태를 조정하는 방법을 제공한다. 에이전트는 동작을 동기화하기 위해 다른 에이전트와 통신한다. 에이전트는 캐릭터의 동작을 조정하는 여러 지능적인 에이전트로 확장되어진다. 에이전트 시스템은 의도된 동작 애니메이션 뿐만 아니라 전체 캐릭터 애니메이션에 대한 동작의 스케쥴링을 가능하게 한다. 에이전트들의 정보를 전달하고 에이전트들의 현 상태를 추론하는 방법으로써 에이전트의 대화를 위한 페트리넷 분석을 이용하여 오토마타 모델을 디자인한다. 에이전트 기술을 이용하여 캐릭터의 동작을 제어하기 위한 에이전트 시스템을 구현한다. 인체 모델 캐릭터의 동작을 제어하는 예를 보이고, 동작 제어의 가능성을 보인다.

• 한국세라믹학회지
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• 제29권9호
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• pp.739-749
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• 1992

The sols prepared by dialyzing solutions, in which the hydrolyzed precipitates of TEOT or directly Ti(OC3H7)4 were resolved, were the nanoparticulate sol with the average particle size less than 7 nm and the anatase crystal phase. In the pH range of 1.5 to 2.9, the particle size of the nanoparticulate TiO2 sols (0.09 mol/ι) increased gradually upto 15 nm~26nm with the increase of pH in the initial aging state but the sols were transparent all the time, and stable without growin any more after 30 days. When the slipcasted porous alumina tubes were coated by the sol-gel dipping method, the minimum particle size and the aging time for forming the coated gel layer at the given pH were optimized. For obtaining the very thin crack-free and reproducible membrane coating, the use of a nanoparticulate TiO2 sol (0.09 mol/ι) aged for about 30 dyas at pH=2.0 was found to be the best.

• Journal of Communications and Networks
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• 제13권4호
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• pp.385-392
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• 2011

A loop can take place in the process of managing tree topology for mobility management of mobile nodes in infrastructure-based mobile ad hoc networks. The formation of a loop degrades an effective bandwidth of the wireless network by passing an identical message repeatedly within the same loop. Therefore, the loop should be resolved to revert the system back to the normal state. In this paper, we propose a simple and novel mechanism that detects and resolves a loop quickly by tracking the depth of trees. The mobility management approach that employs the loop resolution method is evaluated comparatively with the original tree-based one and the hybrid one. It is shown that the proposed approach far outperforms the other approaches, and it is robust against the rapid changes in network topology.

• Journal of Communications and Networks
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• 제13권4호
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• pp.377-384
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• 2011

Cooperative beamforming has previously been proven to be an efficient way to improve the cooperative diversity. This method generally requires all relay nodes to participate in beamforming, which can be seen as "all participate" cooperative beamforming. However, not all relay nodes have constructive impacts on the end-to-end bit error rate (BER) performance. Based on this observation, we propose a new cooperative scheme which only selects those "appropriate" relay nodes to perform cooperative beamforming. Such relay nodes can be simply determined with mean channel gains. Therefore, the selection complexity is significantly reduced as global instantaneous channel state information is not required. This scheme guarantees that energy is only allocated to the "appropriate" relay nodes, and hence provides superior diversity. We also prove that power allocation among source and selected relay nodes is a convex problem, and can be resolved with lower computational complexity. Simulation results demonstrate that our scheme achieves an essential improvement in terms of BER performance for both optimal and limited feedback scenarios, as well as high energy-efficiency for the energy-constrained networks.

• Journal of Photoscience
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• 제11권2호
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• pp.77-81
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• 2004

Deoxygadusol (DO) and structurally related mycosporine-like amino acids, i.e. mycosporine glycine (MO) and mycosporine taurine (MT), were isolated from phytoplankton Prorocentrum micans and studied for the reactivity toward singlet oxygen. These water-soluble compounds with a cyclohexenone chromophore were all shown to be highly effective in quenching singlet oxygen ($^1$ $O_2$), with the efficiencies being significantly larger compared with histidine, a well-known $^1$ $O_2$ quencher. The $^1$ $O_2$ reaction rate constant ( $k_{Q}$) of DG was determined to be 5.4 ${\times}$ 10$^{7}$ $M^{-1}$ $s^{-1}$ by a steady state method based on competitive inhibition of rubrene oxidation. The feasibility of this method was confirmed by estimating the $k_{Q}$ values for MG and two other quenchers, furfuryl alcohol and 1,4-diazabicyclo [2,2,2]octane, and comparing with those values determined by the time-resolved $^1$ $O_2$ decay method in the previous work.ork.