• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.330-335
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• 2000

Functional metal prototypes are often required in numerous industrial applications. These components are typically needed in the early stage of a project to determine form, fit and function. Recent R/P(Rapid Prototyping) part are made of soft materials such as plastics, wax, paper, these master models cannot be employed durable test in real harsh working environment. Parts by direct metal rapid tooling method, such as laser sintering, by now are hard to get net shape, pores of the green parts of powder casting method must be infiltrated to get proper strength as tool, and new type of 3D direct tooling system combining fabrication welding arc and cutting process is reported. But a system which can build directly 3D parts of high performance functional material as metal park would get long period of system development, massive investment and other serious obstacles, such as patent. In this paper, through the rapid tooling process as silicon rubber molding using R/P master model, and fabricate wax pattern in that silicon rubber mold using vacuum casting method, then we translated the wax patterns to numerous metal tool prototypes by new investment casting process combined conventional investment casting with rapid prototyping & rapid tooling process. With this wax-injection-mold-free investment casting, we developed new investment casting process of fabricating numerous functional metal prototypes from one master model, combined 3-D CAD, R/P and conventional investment casting and tried to expect net shape measuring total dimension shrinkage from R/P pare to metal part.

• Journal of Life Science
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• v.31 no.11
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• pp.995-1003
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• 2021

Chromatin remodeling regulates gene expression through epigenetic mechanisms. Aberrations in histone modification have been associated with depression-like behaviors in animal models. Additionally, growing evidence also indicates that epigenetic modification is associated with depression. p11 (S100A10) has been implicated in the pathophysiology of depression both in human and rodent models. In the present study, we investigated alterations in histone acetylation and methylation at the promoter of the p11 gene in the hippocampus of mice subjected to chronic unpredictable stress (CUS). C57BL/6 mice were exposed to CUS daily for 3 weeks. Depression-like behaviors were measured with the forced swimming test (FST). The levels of hippocampal p11 expression were analyzed by quantitative real-time polymerase chain reaction (PCR) and Western blotting. The levels of acetylated and methylated histone H3 at the promoter of p11 were measured by chromatin immunoprecipitation followed by real-time PCR. CUS-exposed mice displayed depression-like behaviors with prolonged immobility in FST. CUS led to significant decreases in the expression of p11 at both protein and mRNA levels. Meanwhile, there was a decrease in histone H3 acetylation (Ac-H3) and H3-K4 trimethylation (H3K4met3) and an increase in H3-K27 trimethylation (H3K27met3) at the p11 promoter. These results indicate that chronic stress causes the epigenetic suppression of p11 expression in the hippocampus.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.82-89
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• 1999

미국의 전파항법정책(FRP Federal Radionavigation Plan)은 여전히 SA정책(미국방성에서 GPS 위성 궤도에 오차를 실어 전파발사를 하는 정책)을 유지하고 있고, P(Y)코드 접속에 의한 고정밀 위치정보 사용 역시 미군 및 NATO군 등 미 국방성에서 인가한 사용자에게만 허용되고 있는 관계로 그 외의 사용자는 3차원 고정밀 위치정보가 요구되는 항공기 이착륙 유도시스템, 해ㆍ육상 정밀 구조/탐색 및 육ㆍ해ㆍ공 특수목적 등에 군사용 P(Y)코드대신 DGPS를 사용하고 있다. 본 연구는 한반도 남해안 및 동해안 일부까지를 유효거리로 하고 있는 일본 Marine Radiobeaeon/DGPS 시스템에 대한 한반도 연근해에서의 위치정보 사용 가능성을 확인하기 위해 한반도 남해안에서 측정 가능한 일본 DGPS국을 선택 모델로 하여 DGPS Data 측정실험 및 위치정보 정밀도 분석을 하였다. 연구결과 군사용 P(Y) 코드수준의 정밀도를 유지하고 있어 곧 구축 예정인 한국형 DGPS 국가망과 함께 선택적으로 사용할 수 있음을 확인하였다.

• Korean Journal of Computational Design and Engineering
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• v.15 no.5
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• pp.343-353
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• 2010

Time to market and cost-efficient production are some of the challenge that manufacturing industries face. Modern methods of engineering can't help such organizations attain competitive advantage. To help these situations, MEMPHIS (Middleware for Exchanging Machinery and Product Data in Highly Immersive Systems) was introduced as an approach that enables VE (Virtual Engineering) and links engineering applications with VR (Virtual Reality) solutions. Thus an environment is provided to implement virtual design reviews and enable the application of virtual prototyping methods. However MEMPHIS could just handle Product data for virtual design review and simulation. In this paper, we newly define and develop the extended MEMPHIS that enables virtual manufacturing with Process, Resource and Plant data as well as Product data.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.708-711
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• 2017

전기적 신호의 이상으로 발생하는 심방 부정맥은 심방세동으로 발전하는 대표적 심장 질환이다. 이러한 원인에는 세포 내 이온 채널의 유전적 결함으로 인한 기전이 알려져 있다. 지속적인 연구로 밝혀진 대표적인 유전적 질환 중 하나로서 KCNH2 유전자 돌연변이가 있다. 본 연구에서는 KCNH2 유전자 돌연변이가 심방부정맥을 유발하는 연관성연구를 기반으로 심실에서의 심장 질환 발현 연관성을 확인하고 심실부정맥과 심실세동 가능성을 예측하였다. 이를 위해 Ten tusscher 세포 모델에 KCNH2 유전자의 N588K, L532P 변이를 적용하여 2차원과 3차원 시뮬레이션을 진행하였다. wild-type(WT)과 mutant-type(MT)의 전기전도 패턴을 비교했다. 그 결과 WT의 전도파형이 일찍 자가소멸(self-termination) 되는 것과 대조적으로 MT는 회귀성 파형이 유지되었다(WT : 3.6초간 유지, MT : 지속적). 따라서 본 연구를 통해 KCNH2 유전자 돌연변이가 심실 조직의 취약성 (Action Potential Duration 감소, WT : 270 ms, N588K : 130 ms, L532P : 100 ms)을 증가시켜 부정맥의 요인이 됨을 확인하였다.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.115-119
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• 2005

The catalytic hydrolysis reactivities of dinuclear nickel (II) complex, ${\mu}-aquapentaaqua[{\mu}-3,6-bis(6'-methyl-2'-pyridyl)pyridazine]chlorodinickel\;(II)$ trichloride trihydrate (APNT) for bis(p-nitrophenyl) phosphate (BNPP) as a DNA model compound were investigated. The dissociation constants of APNT were $pKa_1=7.9$ and $pKa_2=9.6$, respectively. The hydrolysis rate constant of BNPP compound by APNT was showed the rate enhancement of about 370,000 times in the case of none catalyst at pH 7.0 and $50^{\circ}C$. Based on the findings, we proposed the catalytic cycle for the hydrolysis of BNPP by APNT complex. The metal ions of dinuclear nickel (II) complex significantly enhance the transfer rate of phosphoryl group in the catalytic process and the water molecules as nucleophile and proton transfer agent act in different steps.

• Journal of KIISE
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• v.44 no.3
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• pp.306-313
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• 2017

Named entity recognition (NER) seeks to locate and classify named entities in text into pre-defined categories such as names of persons, organizations, locations, expressions of times, etc. Recently, many state-of-the-art NER systems have been implemented with bidirectional LSTM CRFs. Deep learning models based on long short-term memory (LSTM) generally depend on word representations as input. In this paper, we propose an approach to expand word representation by using pre-trained word embedding, part of speech (POS) tag embedding, syllable embedding and named entity dictionary feature vectors. Our experiments show that the proposed approach creates useful word representations as an input of bidirectional LSTM CRFs. Our final presentation shows its efficacy to be 8.05%p higher than baseline NERs with only the pre-trained word embedding vector.

• Journal of the Korea Society of Computer and Information
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• v.15 no.5
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• pp.13-21
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• 2010

The Optimal results of Kalman Filtering on the Inverted Pendulum System requires an effective factor such as the noise covariance matrix Q, the measurement noise covariance matrix R and the initial error covariance matrix $P_0$. We present a special case where the optimality of the filter is not destroyed and not sensitive to scaling of these covariance matrix because these factors are unknown or are known only approximately in the practical situation. Moreover, the error covariance matrices issued by this method predict errors in the state estimate consistent with the scaled covariance matrices and not the issued state estimates. Various results using the scalar gain $\delta$ are derived to described the relations among the three covariance matrices, Kalman Gain and the error covariance matrices. This paper is described as follows: Section III a brief overview of the Inverted Pendulum system. Section IV deals with the mathematical dynamic model of the system used for the computer simulation. Section V presents a various simulation results using the scalar gain.

• The Journal of Korean Institute of Information Technology
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• v.17 no.9
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• pp.19-30
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• 2019

Photovoltaic power generation requires MPPT algorithm to track stable and efficient maximum power output power point according to external changes such as solar radiation and temperature. This study implemented a model that could track MPP more quickly than original MPPT algorithm using artificial neural network. The proposed model finds the current and voltage of MPP using the original MPPT algorithm for various combinations of insolation and temperature for training data of artificial neural networks. The acquired MPP data was learned using the input node as insolation and temperature and the output node as the current and voltage. The Experiment results show tracking time of the original algorithms P&O, InC and Fuzzy were respectively 0.428t, 0.49t and 0.4076t for the 0t~0.3t range, and MPP tracking time of the proposed model was 0.32511t and it is 0.1t faster than the original algorithms.

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.133-142
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• 2005

The settling concentration of fine suspended solid particles(alumina(Al$_2$O$_3$) and quartz(SiO$_2$)) is investigated with the physico-chemical effects(initial concentration, pH and NaCl). Laboratory tests have confirmed the significant influence of increasing initial concentration and salinity which can lead to flocculation due to the intermolecular attraction. Furthermore, the influence of the pH value on the concentration-time corves of alumina has been on firmed. Besides a numerical model to predict the behaviour of cohesive deposit under still water is analyzed by solving the unsteady one-dimensional diffusion-advection equation with a explicit, implicit, Crank-Nicolson and finite difference scheme. The model predicts the existence of an equilibrium concentration. Application of the model with implicit centered difference to data from settling experiments shows a similar distribution.