• Journal of Pharmaceutical Investigation
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• 제40권5호
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• pp.285-289
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• 2010

Manufacturing a multi-layered tablet such as Xatral XL$^{(R)}$ is more complex and expensive than monolayered tablets, but mono-layered tablets may have less favorable release properties depending on the pharmacodynamics and pharmacokinetics of the active ingredient. We therefore sought to develop a monolayer tablet with a similar dissolution profile to the commercial alfuzosin sustained-release triple layered tablet (Xatral XL$^{(R)}$). We prepared four different mono-layered alfuzosin tablets with different concentrations of hydroxypropyl methycellulose and PVP K-90. Fomulation III with alfuzosion/mg-stearate/ HPMC/ PVP K-90 (10/5/110/95 mg/tab) has a similar dissolution rate to Xatral XL$^{(R)}$, with a similarity factor score of 81.4. However, the swelling and erosion rates of the two formulations were different, and NIR analysis showed differences in the mechanisms of drug release. Thus, although formulation III and Xatral XL$^{(R)}$ show similar dissolution rates, the mechanisms of drug release are different.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2018년도 제58차 하계학술대회논문집 26권2호
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• pp.262-264
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• 2018

Many of users play Mobil Social Network Games (M-SNG). M-SNGs are played through social network, and typically features multiplayer and asynchronous gameplay mechanics. It is most often implemented as mobile devices with mobile instant messenger app. Kakaotalk provids mobile game platform. The purpose of this study is to find significant factors that have effects on the commitment of M-SNGs. We also conduct multi-group comparison test to study the difference in factors of models between time t and time t1. Time t is October, 2012 and time t1 is April, 2016. This study is to empirically test the research model using data collected from M-SNGs' users. We survey two different groups of time t and time t1 people with the same model. We use structural equation model analysis with AMOS 18.0 and compare two models of different times. This study is to give academicians and practitioners insight about its effects and implications

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.363-370
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• 2002

This paper presents a production planning algorithm for minimizing the costs of production and subcontracting in SCM (supply chain management) environment. In our SCM environment, the several local plants that aye dispersed geographically produce parts and products. In this environment, we have to decide the production volumes of both parts and products considering the BOM (bill-of-material) structure to meet the fixed order quantity or forecasted demand quantity. Each plant produces the specified parts of product with finite production capacity. There exist subcontracting decisions relevant to the production capacity of each plant except the core process plant, and when we use the subcontractor's capacities we should be charged for the fixed subcontracting fees. The objective of this study is to solve the production planning problem, which minimizes the total costs of production, inventory, setup, and subcontracting under constraints of production and subcontracting capacity. For this problem, an integrated production planning model based on the multi-level capacitated lot sizing problem was formulated, and efficient decomposition algorithm was proposed. The experimental investigation shows that the proposed heuristic generates quite good solutions at very low computational costs.

• 품질경영학회지
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• 제51권4호
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• pp.589-606
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• 2023

Purpose: This study investigates the effects of scuba diving resort service quality on customer satisfaction and revisit intention, considering the moderating effects of perceived risk by scuba divers such as individual, social, and physical risks. Methods: This study surveyed scuba divers using scuba diving resorts in South Korea. The data were analyzed using multi-regression and hierarchical regression analysis. Results: The results of this study are as follows; all five service quality dimensions (tangibles, reliability, responsiveness, assurance, and empathy) significantly affected customer satisfaction and customer satisfaction also affected revisit intention. However, no moderating effect by perceived risk were observed between customer satisfaction and revisit intention. The cause of these results is believed to be the nature of scuba diving as a adventure sport. Conclusion: These results implies that scuba divers' purchase action can be different from the general service users from the perspective of perceived risk. Considering the uniqueness of adventure sports of scuba diving, the managers of scuba diving resorts need to act actively paying attention to all dimensions of service quality, and customer satisfaction.

• 인지과학
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• 제23권4호
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• pp.425-455
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• 2012

다차원 구어 단기기억 기제는 크게 음운적 통로와 어휘-의미적 통로로 구분된다. 전자를 음운단기기억, 후자를 의미단기기억이라고 할 수 있는데, 단기기억 과제를 정상적으로 수행하기 위해서는 두 통로 모두의 정보를 활발히 활용하여야 한다. 그리고 음운단기기억은 다시 음운입력완충기와 음운출력완충기로 나누어지며, 음운입력완충기는 음운자극의 입력 시, 음운출력완충기는 음운 산출 시에 작동한다. 본 연구에서는 유사한 수준의 전도 실어증 증상을 보이는 세 명의 환자에 대해, 각각의 언어 수행력을 구어 단기기억의 다차원적 측면에서 분석하였다. 그러기 위하여 세 명의 전도 실어증 환자들에게 단어 수준과 문장 수준에서 스스로 말하기, 따라말하기, 스스로 쓰기, 받아쓰기의 네 가지 양태의 언어과제를 실시하여 수행력을 비교 분석하였고, 숫자폭검사와 언어학습검사를 이용하여 음운단기기억력과 의미단기기억력을 평가하였다. 그 결과 세 대상자들은 네 양태의 언어 검사에서 다양한 수행력과 오반응 유형을 보였고, 단기기억력 검사 결과도 동일하게 나타나지 않았다. 즉 전도 실어증 환자들의 언어 수행력은 의미단기기억 또는 음운단기기억의 결함으로 설명될 수 있으며, 음운단기기억 가운데에서도 음운입력완충기, 음운출력완충기 혹은 둘 다의 결함 여부에 따라 언어특성이 상이하게 나타날 가능성을 제시하고 있다. 본 연구에서는 전도 실어증 환자들의 언어 검사와 단기기억력 검사 결과를 바탕으로, 언어와 다차원 구어 단기기억력과의 관계에 대하여 논의하고 있다.

• 정보처리학회논문지B
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• 제13B권4호
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• pp.439-448
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• 2006

Kohonen SOM(Self-Organizing Map)이나 MLP(Multi-Layer Perceptron), SVM(Support Vector Machine)과 같은 기존의 인식 및 클러스터링 알고리즘들은 새로운 입력 패턴에 대한 적응성이 떨어지고 학습 패턴 자체의 복잡도에 대한 학습률의 의존도가 크게 나타나는 등 여러 가지 단점이 있다. 이러한 학습 알고리즘의 단점은 문제의 학습 패턴자체의 특성을 잃지 않고 문제의 복잡도를 낮출 수 있다면 보완할 수 있다. 패턴 자체의 특성을 유지하며 복잡도를 낮추는 방법론은 여러 가지가 있으며, 본 논문에서는 커널 공간 해석 기법을 접근 방법으로 한다. 본 논문에서 제안하는 kSOM(kernel based SOM)은 원 공간의 데이터가 갖는 복잡도를 무한대에 가까운 초 고차원의 공간으로 대응시킴으로써 데이터의 분포가 원 공간의 분포에 비해 상대적으로 성긴(spase) 구조적 특정을 지니게 하여 클러스터링 및 인식률의 상승을 보장하는 메커니즘 을 제안한다. 클러스터링 및 인식률의 산출은 본 논문에서 제안한 새로운 유사성 탐색 및 갱신 기법에 근거하여 수행한다. CEDAR DB를 이용한 필기체 문자 클러스터링 및 인식 실험을 통해 기존의 SOM과 본 논문에서 제안한 kSOM과 성능을 비교한다.

• 한국표면공학회지
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• 제38권6호
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• pp.207-211
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• 2005

In this work a multi-layered nanostructured TiAIN/CrN superlattice coatings was synthesized using closed-field unbalanced magnetron sputtering method and the relationships between their superlattice period (1), micro-structure, hardness and elastic modulus were investigated. In addition, wear test at $500^{\circ}C$ and oxidation resistance test at $900^{\circ}C$ were performed to investigate high temperature properties of these thin films. The coatings were characterized in terms of microstructure and mechanical properties by transmission electron microscopy (TEM) and nano-indentation test. Results from TEM analysis showed that superlattice periods was inversely proportional to the jig rotation speed. The maximum hardness and elastic modulus of 37 GPa and 375 GPa were observed at superalttice period of 6.1 nm and 4.4 nm, respectively. An higher value of microhardness from TiAIN/CrN thin films than either TiAIN (30 GPa) or CrN (26 GPa) was noted while the elastic modulus was approximately an average of TiAIN and CrN films. These enhancement effects in superlattice films could be attributed to the resistance to dislocation glide across interface between the CrN and TiAIN layers. Much improved plastic deformation resistance ($H^3/E^2$) of 0.36 from TiAIN/CrN coatings was observed, compared with 0.15 and 0.16 from TiAIN and CrN, respectively. Also the wear resistance at $500^{\circ}C$ was largely increased than those of single TiAIN and CrN coatings and TiAIN/CrN coatings showed much reduced weight gain after exposure at $900^{\circ}C$ for 20 hours.

• 한국재료학회지
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• 제19권12호
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• pp.667-673
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• 2009

The electrocatalytic characteristics of oxygen reduction reaction of the $PtxM_{(1-x)}$ (M = Co, Cu, Ni) supported on multi-walled carbon nanotubes (MWNTs) have been evaluated in a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The $Pt_xM_{(1-x)}$/MWNTs catalysts with a Pt : M atomic ratio of about 3 : 1 were synthesized and applied to the cathode of PEMFC. The crystalline structure and morphology images of the $Pt_xM_{(1-x)}$ particles were characterized by X-ray diffraction and transmission electron microscopy, respectively. The results showed that the crystalline structure of the Pt alloy particles in Pt/MWNTs and $Pt_xM_{(1-x)}$/MWNTs catalysts are seen as FCC, and synthesized $Pt_xM_{(1-x)}$ crystals have lattice parameters smaller than the pure Pt crystal. According to the electrochemical surface area (ESA) calculated with cyclic voltammetry analysis, $Pt_{0.77}Co_{0.23}$/MWNTs catalyst has higher ESA than the other catalysts. The evaluation of a unit cell test using Pt/MWNTs or $Pt_xM_{(1-x)}$/MWNTs as the cathode catalysts demonstrated higher cell performance than did a commercial Pt/C catalyst. Among the MWNTs-supported Pt and $Pt_xM_{(1-x)}$ (M = Co, Cu, Ni) catalysts, the $Pt_{0.77}Co_{0.23}$/MWNTs shows the highest performance with the cathode catalyst of PEMFC because they had the largest ESA.

• 한국기계가공학회지
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• 제20권6호
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• pp.100-107
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• 2021

As a significant technology in the smartization era promoted by the Fourth Industrial Revolution, the secondary battery industry has recently attracted significant attention. The demand for lithium-ion batteries (LIBs), which exhibit excellent performance, is considerably increasing in different industrial fields. During the manufacturing process of LIBs, it is necessary to join the cathode and anode sheets with thicknesses of several tens of micrometers to lead taps of the cathode and anode with thicknesses of several hundreds of micrometers. Ultrasonic welding exhibits excellent bonding when bonded with very thin plates, such as negative and positive electrodes of LIBs, and dissimilar and highly conductive materials. In addition, ultrasonic welding has a small heat-affected zone. In LIBs, Cu is mainly used as the negative electrode sheet, whereas Cu or Ni is used as the negative electrode tab. In this study, one or two electrode sheets (t0.025 mm Cu) were welded to one lead tab (t0.1 mm Cu). The welding energy and pressure were used as welding parameters to determine the welding strength of the interface between two or three welded materials. Finally, the effects of these welding parameters on the welding strength were investigated.

• 한국지구과학회지
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• 제43권1호
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• pp.140-150
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• 2022

이 논문은 울릉도, 독도를 포함하는 동해 울릉분지 해저 화산그룹(가칭: 울릉도-독도 화산그룹)의 분화사를 복원하고 미래 분화 가능성을 평가하기 위해 진행중인 육상-해양 복합 다중스케일 화산연구의 개념과 지금까지의 결과를 소개하는데 목적을 둔다. 다중채널 탄성파반사자료 해석을 통해 유추되는 울릉도-독도 화산그룹의 주 활동 시기는 대략 5-2.5 Ma로, 동쪽 끝의 이사부평정해산에서 처음 시작되어 서쪽의 울릉도로 전파된 것으로 해석된다. 울릉도의 육상부는 5단계에 걸쳐 생성되었으며 최종 단계에 접어들어 폭발성 분화를 통해 폭 약 3 km의 칼데라 지형과 그 내부에 화산돔을 형성하였다. 울릉도의 마지막 분화 산물인 알봉 화산돔과 그 하부의 수증기마그마성 분화로부터 기원된 층단위 N-1 화산쇄설층은 기존 포놀라이트질 마그마방으로 유입된 보다 염기성의 새로운 마그마의 분화로부터 생성되었다. 층단위 N-1과 알봉 분석이 갖는 조면안산암질 전암조성은 기존 포놀라이트질 마그마방 하부에 존재한 고철질 집적암이 새로 주입된 마그마를 오염시킨 결과로, 그 자체가 마그마의 조성을 지시하지는 않는다. 층단위 N-1과 알봉 화산돔에서 확인되는 새로운 마그마 주입의 증거들은 최근 밝혀진 울릉도의 높은 지온구배 및 분화주기와 더불어 울릉도가 여전히 작동중인 마그마 배관체계를 갖는 활화산임을 암시한다.