• Elastomers and Composites
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• v.44 no.4
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• pp.373-377
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• 2009

Most of the plastics products are being manufactured by injection molding. Warpage in injection molded affects the product dimension and it causes assembling problem. In this study, warpages in the injection molded part been studied. Specimens are rectangular flat shapes with and without ribs. Amorphous polymers (PC and ABS) and crystalline polymers (PP and PA66) were used for material. Flat shape with ribs showed higher warpage than flat shape without ribs by 6 to 9%. The specimens with ribs that are located parallel to the flow direction has higher warpage than specimens with ribs that are located perpendicular to the flow direction by 25 to 39%. Crystalline polymers have higher warpage than amorphous polymers by 23 to 67%. Warpage decreases as packing time increases and it increases as injection temperature increases.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.610-610
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• 2013

그래핀을 구성하는 탄소 원자는 모두 표면에 존재하기 때문에, 맞닿아 있는 물질에 따라 그래핀의 물리적 특성에 민감한 영향을 미치기도 한다. 본 연구에서는 라만분광법과 원자 힘 현미경(atomic force microscopy, AFM)을 이용하여 통상적인 열처리 조건에서 그래핀에 탄화수소가 흡착될 수 있는 가능성을 탐구하였다. 산소가 없는 조건에서 열처리된 그래핀으로부터 D, G, 2D 봉우리와 겹쳐지는 폭이 넓은 새로운 라만 봉우리들이 관찰되었다. 열처리 시간, 온도 및 진공도에 따른 라만 스펙트럼의 변화와AFM에 의해 확인된 표면의 구조 변화로부터 새로이 관찰된 라만 봉우리는 탄화수소의 탄화에 의해 그래핀의 표면에 형성된 비결정성 탄소물질(amorphous carbon)임을 확인하였다. 기계적 박리법과 화학기상증착법으로 시료를 준비할 때 사용된 폴리머 잔유물이 열처리 과정에서 탄화수소를 배출하는 것으로 판단된다. 이 연구는 그래핀 소자의 작동에 있어서 환경적인 효과를 이해하고 탄화에 의해 그래핀 표면에 만들어진 비결정질 탄소를 정량화하는데 도움을 줄 것이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1020-1023
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• 2008

멀티스레드 프로그램의 효과적인 디버깅을 위해서는 스레드의 비결정성에 의해 야기되는 다양한 수행 양상의 직관적인 이해가 중요하다. 스레드 수행 양상을 시각화하는 기존의 기법들은 공유 변수의 접근사건들 간의 부분 순서를 표현함으로써 시각적 복잡도가 높거나 이전 수행에서 결정된 락킹 순서를 표현하여 잠재되어 있는 다른 수행 양상에 대한 정보를 제공하지 못 한다. 본 논문은 프로그램 수행의 비결정적인 부분 순서는 락의 종류와 속성을 포함하는 코드 블록으로 시각화하고, 결정적인 부분 순서는 블록들을 연결하는 간선으로 시각화한다. 본 연구의 그래프는 플랫폼에 독립적인 Java Swing으로 구현하고 합성 프로그램을 사용하여 효과성을 실험한다.

• Polymer(Korea)
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• v.24 no.1
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• pp.128-132
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• 2000

The miscibility between poly(vinyl chloride) (PVC) and polycaprolactone (PCL)-polyamide block copolymer whose content of PCL block is 62.7 wt%, was studied by differential scanning calorimetry. The PCL segment in the block copolymer and PVC has the miscibility showing single glass transition temperature (T$_{g}$). The miscible PVC molecule inhibited the crystallization of PCL segment, making an amorphous homogeneous phase of PCL and PVC segments at high PVC content. The blends had rubber elasticity at the temperature range between the T$_{g}$ of amorphous homogeneous phase of PCL and PVC segments and the melting temperature of polyamide segment, when both phases coexist.ist.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1854-1866
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• 1997

This paper proposes a new test case generation technique for a nondeterministic finite state machine by improving the existing UIO sequence generation method. First, a new conformance relationis defined, which is one of prerequisites for automatic test case generation. Because fof the nondeterministic property of torpocols, the output of the systems under test is not known deterministically to the tester. Therefore, tree-like test case generation method is introduced for adaptive testing, in which the next input is selected after observing the previous output. Since the test cases are generated with regarding the inputs and outputs as separate events and are represented in tree notation, the test cases are easily converted into TTCN, the international standard test suite specification language.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1065-1069
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• 1998

This study was investigated to improve peformance of carbon negative electrode for lithium ion secondary battery. The carbon electrode was prepared by mixing with graphitic carbon material, natural graphite, and nongraphitic carbon material, petroleum cokes, which was heat-treated at $700^{\circ}C$ for l hour. Its electrochemical and charge-discharge characteristics were tested according to mixing ratio of different two types of carbon material. The carbon electrode prepared with various mixing ratio showed both charateristcs of two different types of carbon materials and the best characteristics as carbon electrode was demonstrated at mixing ratio of 1:1.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.9
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• pp.424-433
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• 2001

The cyclic debugging approach often fails for message passing parallel programs because they non-deterministic characteristics due to message race conditions. This paper identifies the MPI events that affect non-deterministic executions, and then converts the concurrent execution to the sequential one that is controlled in order to make it equivalent to a reference execution by keeping their orders of events in two executions identical. This paper also presents an efficient algorithm for the causal distributed breakpoint which is initiated by any sequential breakpoint in one process, and restores each process to the earliest state that reflects all events that happened causally before the sequential breakpoint. So a cyclic debugging approach can be used in debugging MPI parallel programs as like as in debugging sequential programming environments.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.173-178
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• 2005

Recently plastic parts are molded for the purpose of mass production in multi-cavity system. Therefore, designer is usually designing mold that has geometrically balanced runner lay-out for filling balance at each cavity. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in the cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this study, based on previous studies for filling imbalances in cold-runner mold, filling imbalances in hot-runner mold were investigated by CAE and injection molding experiments. ABS and PMMA as amorphous polymer, PA as crystalline polymer were used to compare the filling imbalances. There were different results of CAE and experiment. The filling imbalances decreased as injection rate increased without regard to kind of resins and were lower than the one of cold-runner.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.598-601
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• 2005

Plastic parts are molded for the purpose of mass production in multi-cavity system. Therefore, designer is usually designing molds that has geometrically balanced runner lay-out for filling balance at each cavities. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this study, based on previous studies for filling imbalances in cold-runner mold, filling imbalances in hot-runner mold were investigated by CAE and injection molding experiments. ABS, PMMA as amorphous polymer and PA, PP as crystalline polymer were used to compare the filling imbalances. The filling imbalances decreased as injection rate increased without regard to kind of resins and were lower than the one of cold-runner.

• Korean Journal of Cognitive Science
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• v.15 no.1
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• pp.25-33
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• 2004

This paper discusses two problems with LR parsing with regard to constructing parsing tables with feature-based grammars. First, we show that traditional LR parsing methods suffer from nontermination and nondeterminism problems when they are applied to feature-based grammars. We then present an LR method for feature-based grammars that avoids both nontermination and nondetermisim by making use of partial information of a feature structure. Second, we describe the problem of adapting LR parsing to feature-based grammars with schematic rules (i.e., rules that do not contain enough information to construct parsing tables). To remedy this problem, we propose a rule inference algorithm which instantiates underspecified rules into more specified ones containing enough information.