• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 춘계학술대회 논문집
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• pp.328-332
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• 1993

Single overload tests are carried out for SS41. Specimens are used hollow type and solid type that stress condition prevail plane stress and plane strain at surface crack. According to the crack initiation and propagation period, single overload applies to three regime and overload ratios change into 1.5, 2.0. Crack retardation zones at initation range aren't different in both specimens respectively, however at propagation range come into large scale in hollow specimen. Delayed load cycles come into large scale in solid type. And the more the overload ratio increase, the larger the retardation zone increase but the magnitude doesn't exactly equal to the expected from the overload ratio.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(2)
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• pp.1353-1354
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• 2005

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.503-506
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• 1998

We demonstrate stable return-to-zere direct pulse modulation of a gain-switched DFB semiconductor laser at a data rate of 2.5 Gbit/s. The effects of change in drive conditions on eye diagrams of the outputs are explored and an optimum operating regime is determined.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.355-355
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• 2018

Natural hydrology systems, including high flow and low flow events, are important for aquatic ecosystem health and are essential for controlling the structure and function of ecological processes in river ecosystems. Ecosystem responses to flow changes have been studied in a variety of ways, but little attention has been given to how episodic typhoons and atmospheric circulation patterns can change these hydrologic regime-ecological response relationships. In this diagnostic study, we use an empirical approach to investigate the salient features of interactions between atmospheric circulation, climate, and runoff in the five major Korean river basins.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.85-90
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• 2004

We have presented characteristics of a transitional behavior from a premixed flame to a triple flame in a lifted flame according to the change of equivalence ratio. The experimental apparatus consisted of a slot burner and a contraction nozzle for a lifted flame. As concentration difference of the both side of slot burner increases, the shape of flame changed from a premixed flame to a triple flame, and the liftoff height is decreased to the minimum value and then increase again. Around this minimum point, it is confirmed a transition regime from premixed flame to triple flame. Consequently, the experimental results of the liftoff height, flame curvature and luminescence intensity showed that the stabilized laminar lifted flame regime is categorized by regimes of premixed flame, triple flame and critical flame. In the visualization experiment of smoke wire, the flow divergence and redirection reappeared in premixed flame as well as triple flame. Thus we cannot express the flame front of lifted flame has a behavior of triple flame with only flow divergence and redirection. To differentiate triple flame and premixed flame, ${\Phi}$ value of partially premixed fraction is employed. The partially premixed fraction ${\Phi}$ was constant in premixed flame. In critical flame small gradient appears over the whole regime. In triple flame, typical diffusion flame shape is obtained as parabolic distribution type due to diffusion flame trailing.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제23권1호
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• pp.39-51
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• 1995

Bidirectional transport trend using the sediment-transport path model was identified in the two areas, sand ridge area and tidal mudflat in Garolim Bay, which is located in the mid-western coast of Korean Peninsular. This model exhibits the two-dimensional view of clear sediment transport trend based on data of changes in sediment statistics such as mean, sorting, and skewness, Garolim Bay was selected to test for the sediment-transport path model developed by McLaren and Bowles [1985]. Line-S, a typical tidal mudflat and representative of the Garolim Bay tidal flats, is well tested by this model, showing a clear seasonal change and coarsening-trend seaward (case C). This indicates that strong ebb currents carried relatively coarser sediments seaward with respect to high energy regime. Seasonally, this energy regime slowly decreases toward the summer in contrast with an increase of energy regime of flood tides, carrying coarser sediments landward (case C) in the summer. However, the Line-D area does not show consistent transport trend with respect to time-series. Separated and scattered events show fining trend landward (case B) in the sand ridge itself. The finining-trend (case B) either seaward and landward is not chiefly important in both the entire Line-D area and sand ridge itself. Also, the coarsening-Trend (case C) landward is not significant in the sand ridge itself. Consequently, in reality, the selection of suitable and representative locations are very important to fit with this model.

• Wind and Structures
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• 제30권4호
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• pp.367-378
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• 2020

Two-dimensional Delayed Detached Eddy Simulation (DDES) was carried out to investigate the uniform flow over a twin-box bridge deck (TBBD) with various gap ratios of L/C=5.1%, 12.8%, 25.6%, 38.5%, 73.3% and 108.2% (L: the gap-width between two girders, C: the chord length of a single girder) at Reynolds number, Re=4×104. The aerodynamic coefficients of the prototype deck with gap ratio of 73.3% obtained from the present simulation were compared with the previous experimental and numerical data for different attack angles to validate the present numerical method. Particular attention is devoted to the fluctuating pressure distribution and forces, shear layer reattachment position, wake velocity and flow pattern in order to understand the effects of gap ratio on dynamic flow interaction with the twin-box bridge deck. The flow structure is sensitive to the gap, thus a change in L/C thus leads to single-side shedding regime at L/C≤25.6%, and co-shedding regime at L/C≥35.8% distinguished by drastic changes in flow structure and vortex shedding. The gap-ratio-dependent Strouhal number gradually increases from 0.12 to 0.27, though the domain frequencies of vortices shedding from two girders are identical. The mean and fluctuating pressure distributions is significantly influenced by the flow pattern, and thus the fluctuating lift force on two girders increases or decreases with increasing of L/C in the single-side shedding and co-shedding regime, respectively. In addition, the flow mechanisms for the variation in aerodynamic performance with respect to gap ratios are discussed in detail.

• Journal of health informatics and statistics
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• 제43권4호
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• pp.274-281
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• 2018

Objectives: The purpose of this study is to comprehensively compare the trends of health administration and health policy in the field of health care using the semantic network analysis in the inaugural address of the Ministry of Health and Welfare of each regime in Korea. Methods: This study used a language network analysis method that uses Korean Key Words In Context (KrKwic) program and NetMiner program in sequence. The analysis was conducted by Minister Hwa-joong Kim during the Moo-hyun Roh government, Minister Jae-hee Jeon during the Myung-bak Lee government, Minister Young Jin of Geun-hye Park government and Government Jae-in Moon's inaugural address of Neung-Hoo Park Minister, respectively. Results: The key words differentiated by each regime are that the Moo-hyun Roh Government's Minister Hwa-joong Kim had high connection centrality values in the words 'balanced development', 'comprehensive' and 'reform'. Minister Jae-Hee Jeon of Myung-bak Lee Government had high connection centrality values in the words 'poverty' and 'return'. In the case of Minister Young Jin of Geun-hye Park Government had high connection centrality values in the words 'demand', 'Customized' and 'Life cycle'. In the case of Minister Neung-Hoo Park of Jae In Moon Government had high connection centrality values in the words 'Welfare state', 'Embracing' and 'Soundness'. Conclusions: If the role of health administration in the health care field and the health care policies are constantly changed according to the policies of each regime, it is inconsistent and it is difficult to approach from the long term perspective for public health promotion. In the future, health policy should be developed and implemented with a long-term perspective and consistency based on the consensus and participation of the people with less influence on the change and direction of each government's policies.

• 정보관리학회지
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• 제41권1호
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• pp.107-132
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• 2024

이 연구에서는 한국언론진흥재단의 빅카인즈에서 제공하는 1990년부터 2022년까지 약 30년간의 5·18 관련 뉴스데이터를 빈도분석과 네트워크 분석하였다. 구체적으로 시기별과 지역별 기사량을 분석하여 양적 변화 추이를 살펴보았으며 동시 출현 키워드를 활용한 정부별 네트워크 분석을 통해 정부별 주요 키워드 간의 연결 구조를 탐색하였다. 분석 결과, 시기적으로는 사회적 이슈가 많았던 2019년의 보도량이 가장 많은 것으로 나타났으며 지역적으로는 전라권의 보도량이 가장 많은 것으로 나타났다. 그리고 네트워크 분석 결과, 정권이 5·18을 바라보는 인식과 정책에 따라 뉴스데이터 내 5·18과 관련된 단어에 차이가 있었다. 5·18 뉴스데이터 분석을 종합한 결과, 5·18이 지역과 상관없이 시간이 지남에 따라 민주화운동으로 자리매김해 나가고 있었으나 동시에 5·18에 대한 왜곡이 해소되지 못하고 있음을 확인하였다.

• International Journal of Automotive Technology
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• 제6권1호
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• pp.45-52
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• 2005

Interrupted creep tests for investigating the structural degradation during creep were conducted for a Mod.9Cr-1Mo steel in the range of stress from 71 to 167 MPa and temperature from 873 to 923 K. The change of hardness and tempered martensitic lath width was measured in grip and gauge parts of interrupted creep specimens. The lath structure was thermally stable in static conditions. However, it was not stable during creep, and the structural change was enhanced by creep strain. The relation between the change in lath width and creep strain was described quantitatively. The change in Vickers hardness was expressed by a single valued function of creep LCR(life consumption ratio). Based on the empirical relation between strain and lath width, a model was proposed to describe the relation between change in hardness and creep LCR. The comparison of the model with the empirical relation suggests that about 65% of hardness loss is due to the decrease of dislocation density accompanied by the movement of lath boundaries. The role of precipitates on subboundaries was discussed in connection with the abnormal subgrain growth appearing in low stress regime.