• 한국세라믹학회지
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• 제16권4호
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• pp.206-212
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• 1979

The phase relations and microstructure appeared at 1700℃ in a system of Si3N4-Al2O3-SiO2 were studied. The samples were pressurelessly sintered at 1700℃ for 1hr and reheated at 1600℃ for 1hr under nitrogen atmosphere. The compounds formed were identified by X-ray diffraction method and the microstrues were observed by SEM. The stable phases appeared in this system were X-phase, Si2ON2, β'-Si3N4 and Mullite. From the results of those experiments, it was concluded that the X-phase has very close composition to that proposed by G, K. Layden, Si3Al6O12N2. SEM photographs showed that Si2ON2 was a plate phase and X-phase was a rectagular plate phase.

• 한국정밀공학회지
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• 제19권7호
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• pp.36-42
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• 2002

This paper presents two actuators for levitation using repulsions of permanent magnet and two magnetic levitation tables using the actuators. Here, one actuator for levitation consists of one fixed magnet and one moving magnet, and the other actuator consists of two fixed magnets and one moving magnet. The moving part of the magnetic levitation table contains the moving magnets. repulsive forces caused by the permanent magnets are linearized, and then the equation of motion of the moving part of the table is derived. Using the equation of motion, stability conditions of the moving part are deduced. The stability conditions are analyzed for positional relations of the moving magnets and the minimum number of active control required for stable system. As a result, in the each case of magnetic levitation tables, the requirements for stabilization are expressed by the positional relations and the number of the active controls.

• 한국지구과학회지
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• 제23권1호
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• pp.105-111
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• 2002

The observation of the new biotite isograd (chlorite + chloritoid = andalusite + biotite) in the Mungyong coal field requires the modification of Harte and Hudson's (1979) metapelite grid which eliminates the stability field of staurolite + cordierite assemblages. The newly proposed metapelite grid by Ahn and Nakamura (2000) can define more properly the isograd reaction observed from nature. We discuss first topological interrelations between synthetic system (FASHO-, KFASHO-, KFMASH system) on an isobaric section at 2kbar, where phase relations are well constrained. The following discussion is concentrated on the topological relations between stable reactions. At the last, we discuss the petrogenetic significance of the Ahn's petrogenetic grid compared with theoretically computed grids. Ahn's petrogenetic grid is consistent with synthetic and natural system, and is one of the excellent example of KFMASH approximation in metapelite.

• 한국지진공학회논문집
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• 제10권3호
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• pp.101-111
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• 2006

이 논문에서는 안정대륙권역(Stable Continental Regions, SCRs)에서의 중규모 지진에 의한 근단층지반운동(Near Fault Ground Motion, NFGM) 모델을 처음으로 제시한다. 근단층지반운동은 큰 진폭의 장주기 속도 펄스를 갖는 특징을 가지고 있다. 이 속도 펄스를 모델링하기 위해서는 그 주기와 진폭을 지진의 규모와 단층거리의 함수로 표현할 수 있어야 한다. 그런데 안정대륙권역에서는 관측 자료가 빈약하여 지진데이터로부터 이 관계식을 직접 유도하는 것은 어렵기 때문에 이 연구에서는 간접적인 접근법을 채택하였다. 속도 펄스의 주기와 진폭은 단층파열의 상승시간과 파열속도의 함수임이 알려져 있고 활성구조권역(Active Tectonic Regions, ATRs)에 속하는 미국 서부지역에서는 실험적 공식이 확립되어 있다. 안정대륙권역에서의 상승시간과 단층파열속도의 지진규모에 대한 함수관계는 WUS와 CEUS에서의 자료를 비교하여 도출하였다. 이 관계식들로부터 안정대륙권역에서의 NFGM의 속도 펄스의 주기와 진폭을 지진규모 및 단층 거리에 대한 관계식으로 유도하였다. 안정대륙권역에서의 NFGM의 가속도 시간이력은 추계학적으로 생성된 원역지진지반가속도에 새로운 관계식에 의한 속도 펄스를 중첩하여 얻어진다. 적용 예제로서 탄소성 단자유도 시스템의 근단층지반운동에 대한 응답을 분석하였다.

• 자원환경지질
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• 제36권5호
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• pp.329-338
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• 2003

이 연구는 무주군 적상산 부근에 위치하는 소유역(100$Km^2$)에서 지표수와 천부 지하수의 안정동위원소 조성의 시공간적 변화를 조사하기 위해서 실시되었다. 시료채취는 2001년 8월(여름)과 10월(가을), 2002년 4월(봄), 3회에 걸쳐 실시되었다. 지표수의 동위원소 조성은 계절에 따라 뚜렷이 구분되어 도시되지만 천부 지하수에서는 이러한 변화가 줄어든 것이 관찰되었다. 하지만 지표수와 지하수의 안정동위원소 조성의 변화 폭은 계절별로 서로 유사하게 나타나고 있다. 이것은 이 지역에서 강수, 지표수 및 지하수 사이의 상호작용이 매우 활발하며 지속적으로 일어나고 있음을 의미한다. 무주지역 지표수의 안정동위원소 조성은 남쪽에 위치하는 섬진강의 조성보다는 가벼운 “위도효과”를 나타내고 있다. 또한 하천수에는 동위원소 조성의 계절변화와 아울러 강수의 “고도효과”와 “우량효과”가 잘 반영되어 있음이 관찰되었다.

• 한국주거학회논문집
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• 제9권3호
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• pp.107-118
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• 1998

In order to provide the basic data for planning of stairways design in elderly housing, the study of Ergonomics were exmined. 3 old women and 3 female subjects were tested: 1) The relations between blood pressure and pulse: In case of the old, blood pressure was the highest at 13 cm and pulse was the highest at 23 cm. But in case of the young, the former was the highest at 23 cm and the latter was at 13 cm. 2) EMG: According to the height of stairs, the significant differences on the statistics were not seen. 3) Riviewing that biological characters according to the finishing materials, in case of the old groups, they feel most stable, as they up the wooden stairs. While they feel very dangerous, as they up the stairs where carpet is on. In the biological characters according to the stairs heights and the finishing materials, the most stable conditions for the old are 15 cm-high-stairs, wooden. And even if the stairs used inside the house, the installment of the handrails at both side must be considered.

• 대한수학회지
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• 제45권2호
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• pp.493-511
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• 2008

In this article, we study the relations of horizontally homothetic harmonic morphisms with the stability of totally geodesic submanifolds. Let $\varphi:(M^n,g)\rightarrow(N^m,h)$ be a horizontally homothetic harmonic morphism from a Riemannian manifold into a Riemannian manifold of non-positive sectional curvature and let T be the tensor measuring minimality or totally geodesics of fibers of $\varphi$. We prove that if T is parallel and the horizontal distribution is integrable, then for any totally geodesic submanifold P in N, the inverse set, $\varphi^{-1}$(P), is volume-stable in M. In case that P is a totally geodesic hypersurface the condition on the curvature can be weakened to Ricci curvature.

• Animal cells and systems
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• 제14권4호
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• pp.297-303
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• 2010

To document the basic ecological aspects of Chaoborus species, which has never been reported in Korea, we attempted to identify the species, to monitor seasonal and vertical dynamics, and to elucidate trophic relations of the species in Sang-Chun reservoir. Using morphological characteristics, we identified the collected samples as C. flavicans. Also, we compared the distribution of C. flavicans, Daphnia rosea and chlorophyll a to observed seasonal dynamics. The increase of C. flavicans was observed 1-2 weeks after the increase of D. rosea. Survey of diel vertica migration patterns in the summer season showed that C. flavicans were in hypolimnion at daytime, but moved to the epilimnion at night. Finally, to determine trophic relationships in Sang-Chun reservoir, additional studies on the food web were undertaken by stable isotope analysis. Chaoborus flavicans I-II instars appear to be filter feeders based on carbon isotope values. Trophic levels of C. flavicans III-IV instars were shown to be higher than other zooplankto based on nitrogen isotope values.

• 대한치과보철학회지
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• 제50권4호
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• pp.311-317
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• 2012

총의치 장착시, 환자는 생리적으로 안정된 범위 내에서 자연스럽게 기능하기를 원하며 이를 위해서는, 안모의 회복(심미적 효과), 생물학적으로 안정된 인공치 배열과 외형, 의치 동요가 없는 교합접촉이 반드시 필요하다. 이에 본 증례보고에서는 총의치를 제작하기에 불리한 조건을 가진 환자를 대상으로 인상면, 연마면, 교합면에 있어서의 의치의 안정을 증대시키기 위해, 기능적 변연 형성을 통한 인상채득, 중립대 확인, 생리적 중심위 재확립, 안정된 교합을 형성시켜 주었으며, 임상적으로 기능과 심미적인 측면에 있어서 만족할 만한 결과를 얻었기에 이를 보고하고자 한다.

• Strategy21
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• 통권36호
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• pp.5-32
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• 2015

Geopolitics or Political Geography is an essential academic field that should be studied carefully for a more comprehensive analysis of international security relations. However, because of its tarnished image as an ideology that supported the NAZI German expansion and aggression, geopolitics has not been regarded as a pure academic field and was rejected and expelled from the academic communities starting from the Cold War years in 1945. During the Cold War, ideology, rather than geography, was considered more important in conducting and analyzing international relations. However, after the end of the Cold War and with the beginning of a new era in which territorial and religious confrontations are taking place among nations - including sub national tribal political organizations such as the Al Quaeda and other terrorist organizations - geopolitical analysis again is in vogue among the scholars and analysts on international security affairs. Most of the conflicts in international relations that is occurring now in the post-Cold War years can be explained more effectively with geopolitical concepts. The post - Cold War international relations among East Asian countries are especially better explained with geopolitical concepts. Unlike Europe, where peaceful development took place after the Cold War, China, Japan, Korea, the United States, Taiwan and Vietnam are feeling more insecure in the post-Cold War years. Most of the East Asian nations' economies have burgeoned during the Cold War years under the protection of the international security structure provided by the two superpowers. However, after the Cold War years, the international security structure has not been stable in East Asia and thus most of the East Asian nations began to build up stronger military forces of their own. Because most of the East Asian nations' national security and economy depend on the oceans, these nations desire to obtain more powerful navies and try to occupy islands, islets, or even rocks that may seem like a strategic asset for their economy and security. In this regard, the western Pacific Ocean is becoming a place of confrontation among the East Asian nations. As Robert Kaplan, an eminent international analyst, mentioned, East Asia is a Seascape while Europe is a Landscape. The possibility of international conflict on the waters of East Asia is higher than in any other period in East Asia's international history.