• 한국항해항만학회지
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• 제33권4호
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• pp.255-261
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• 2009

Prediction of the stability for ships is very complex in reality. In this paper, risk based approach is applied to predict the probability of capsize for a certified ship, which is effected by the forces of sea especially the wave loading Safety assessment and risk analysis process are also applied for the probabilistic prediction of stability for ships. The probability of shipsencountering different waves at sea is calculated by the existed statistics data and risk based models. Finally, ship capsizing probability is calculated according to single degree of freedom(SDF) rolling differential equation and basin erosion theory of nonlinear dynamics. Calculation results show that the survival probabilities of ship excited by the forces of the seas, especially in the beam seas status, can be predicted by the risk based method.

• 한국해양공학회지
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• 제22권6호
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• pp.46-51
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• 2008

The effect of the addition of Co and N and subzero treatment on tensile strength and damping capacity was investigated in Fe-Cr-Mn alloy. Austenite was transformed into martensite by cold rollins increasing the degree of cold rollins led to an increase in the volume fraction of martensite. The damping capacity linearly increased with increasing volume fraction of ${\varepsilon}$ martensite in cold rolled specimens and subzero treated specimens after cold rolling. The volume fraction of ${\varepsilon}$ martensite, tensile strength and damping capacity was also increased by the addition of Co, while this treatment decreased the elongation. However, the volume fraction of ${\varepsilon}$ martensite, elongation and damping capacity were reduced by the addition of N, although the tensile strength increased. Tensile strength and damping capacity werealso increased by subzero treatment, while elongation decreased.

• 동력기계공학회지
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• 제8권4호
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• pp.31-37
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• 2004

The damping capacity and strength of Fe-2Al-26Mn alloys have been studied for the development of new materials with high strength and damping capacity. Particularly, the effect of ${\alpha}'\;and\;{\varepsilon}$ martensite phase, which constitutes the microstructure of cold rolled Fe-Al-Mn alloys, has been investigated in terms of the strength and damping capacity of the alloys. The damping capacity rises with increasing the degree of cold rolling and reveals the maximum value at 25% reduction. The damping capacity is strongly affected by the volume fraction of ${\varepsilon}$ martensite, while the other phases, such as ${\alpha}'$ martensite and austenite phase, actually exhibit little effect on damping capacity. Considering that tensile strength increases and elongation decreases with increasing the volume fraction of ${\alpha}'$ martensite, it is proved that tensile strength is mainly affected by the amount of ${\alpha}'$ martensite.

• Applied Microscopy
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• 제7권1호
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• pp.45-49
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• 1977

용탕의 온도는 탄소의 비율을 높이기 위하여 $1500^{\circ}C$ 이하로 해야 하며, 주입온도는 $1460^{\circ}C$ 내외가 적당하다. 주조상태에서 소지의 침상석출물은 orthorhombic $(Fe,\;Mn)_3C$로 판명되었다. 냉간압연비는 클수록 결정이 미세화되고 또한 경도도 증가하였다. 표면탈탄이 얼어 나면 표면층에 martensite가 형성되어 성형하기가 어려우므로 argon 분위기를 쓰는 것이 좋았다. 두께 1 mm 판재의 경우 수인처리 온도가 $950^{\circ}C$ 이하일 때 탄화물 stringer 가 나타났고, $1020^{\circ}C$ 에서 30 분간 가열했을 때 탄화물이 의 소지에 고용되었다. C 함량이 클수록 인장강도와 연신률이 증가하였다. Ni, Cr 및 V 을 미량 첨가했을 때 인장강도 및 연신률이 커졌으며 또한 굽힘성도 좋았다.

• 한국재료학회지
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• 제25권1호
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• pp.9-15
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• 2015

The effect of retained and reversed austenite on the damping capacity in high manganese stainless steel with two phases of martensite and austenite was studied. The two phase structure of martensite and retained austenite was obtained by deformation for various degrees of deformation, and a two phase structure of martensite and reverse austenite was obtained by reverse annealing treatment for various temperatures after 70 % cold rolling. With the increase in the degree of deformation, the retained austenite and damping capacity rapidly decreased, with an increase in the reverse annealing temperature, the reversed austenite and damping capacity rapidly increased. With the volume fraction of the retained and reverse austenite, the damping capacity increased rapidly. At same volume of retained and reversed austenite, the damping capacity of the reversed austenite was higher than the retained austenite. Thus, the damping capacity was affected greatly by the reversed austenite.

• 드라이브 ㆍ 컨트롤
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• 제10권4호
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• pp.14-21
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• 2013

The numerical analysis of the automatic ship mooring system which was equipped in the ship for trying to berth at the pier was performed in this study. The automatic ship mooring using hydraulic winch was a new method that had not need to change the existing devices and to help a pilot ship of outside. The numerical results of the proposed mooring system including ship motion were that the speed and rolling phenomenon of ship was affected by changing in the ship weight and affected the slope maintenance and yaw degree of ship if there has a trim of stern. Also, a static force of ship at the initial movement was important to calculate the mooring power. The moving force and inertial force of ship on the vertical direction was confirmed for the mooring stability. Therefore, the power and velocity of hydraulic mooring winch should be determined by considering the significant characteristics such as weight, velocity, inertial force and moving force of ship.

• The Journal of Asian Finance, Economics and Business
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• 제9권5호
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• pp.19-27
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• 2022

The size of the government is one of the most fundamental debates of open economies. In any economy, government plays an important role, but a pertinent level of economic prosperity has never been obtained in history without government. Therefore, the objective of this paper investigates the association of government size, economic volatility, and institutional quality for 182 economies from the time period 1996-2016 is collected from the World Bank database. GE is defined as the General government's final consumption expenditure. Health expenditure is represented by HE. Government expenditure on education is denoted by EDUEXP. The economic volatility is measured by the rolling standard deviation of GDP per capita growth rate, Population growth, Trade openness, GINI represented Gini index which measures the degree to which the income distributed or consumption expenses among citizens deviates from a perfectly equal distribution. The results proposed that economic volatility has a significant effect on government size and institutional qualities. Moreover, the paper extends the investigation by finding the link between economic volatility with government health and education expenditure separately. The policy implication drawn from this analysis is that controlling economic volatility may reduce the size of government and also significantly affect health and education expenditures.

• 아태비즈니스연구
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• 제13권4호
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• pp.109-121
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• 2022

Purpose - This study investigates how earnings volatility influences current stock price informativeness about expectations of future earnings. Design/methodology/approach - I adopt the FERC model developed by Collins et al. (1994) and modified by Lundholm and Myers (2002) to investigate the connection between earnings volatility and future earnings reflected in current returns. I define five-year rolling standard deviations of earnings and components as earnings volatility measures and the degree of deviation of earnings from cash flows over the same five-year, which is developed by Jayaraman (2008). Finding - My results show that earnings volatility delays current stock price response to future operation expectations. They also verify that as earnings are more divergent from cash flows, current returns are less timely incorporating value-relevant future operation. Research implications or Originality This study shows that when volatile earnings deliver obscure and unreliable information about future operation expectations, they cause the market to be conflicting in understandings their implications and make it difficult in attaining correct future cashflow estimates.

• 치위생과학회지
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• 제9권3호
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• pp.345-351
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• 2009

본 연구는 당뇨병 환자들의 구강건강지식 정도 및 구강관리실태와의 관련성을 파악하여 구강건강에 대한 교육의 필요성 도출과 구강건강교육 프로그램을 개발하는데 필요한 기초 자료로 활용하고자 당뇨병 환자 121명을 대상으로 설문 조사한 자료를 통하여 다음과 같은 결론을 얻었다. 1. 일반적 특성에 따른 구강건강 지식정도는 여자가 남자보다 높았고, 연령별로는 20개 이하와 50대 이상인 집단에서 구강건강 지식이 높았으며, 당뇨 유병기간이 길수록 지식정도가 높은 것으로 조사되었다. 2. 구강관리실태 중 잇솔질 방법은 전체 연구 대상자의 21.5%만이 회전법이라 답하였으며, 구강건강 지식정도가 상인 경우 당뇨 진단 후 치과치료 경험이 많았으며, 구강질병 상담자는 치과의사가 가장 많은 것으로 나타났다. 3. 연구 대상자가 치과치료를 망설이는 이유로는 모든 집단에서 '치료비용이 비싸서'라고 답하였고, '당뇨와 구강질환이 상관이 없어서'라는 항목의 경우 구강건강 지식정도가 상인 집단에서 가상 높게 나타났다. 4. 구강건강 지식정도와 구강건강교육 여부의 경우 구강건강 교육용 받았었거나, 받고 있는 당뇨병 환자일수록 구강건강 지식정도가 높게 나타났다. 5. 구강건강 지식정도가 중인 집단에서 대부분의 구강관리행위에 높은 점수를 부여하는 것으로 조사되었으나 통계적 유의성을 보이지 않았다.

• 한국구조물진단유지관리공학회 논문집
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• 제15권4호
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• pp.204-211
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• 2011

고속철 교량의 동적응답을 보다 정밀하게 해석하기 위한 동적해석방법을 개발하였다. 차후 증가될 초고속(450km/h)을 포함하여 고속 주행하는 KTX 동력차에 의한 교량의 동적거동을 면밀한 속도변수분석과 정밀한 해석을 위한 고속철, 교량 그리고 궤도구조물의 상호작용을 포함한 수치모델을 구성하였다. 네 가지 40~25미터 단순지간의 PSC 박스교를 3차원 유한 프레임요소 모델로 개발하였다. 스펙트럼밀도함수로 산출된 궤도불규칙값과 궤도간 상이한 거리차이를 수치모델화 하였다. 고속철차량은 (KTX) 38자유도로 구성하였다. 38자유도 모델은 3방향 변위와 상응하는 회전각을 고려하였다. 동적증폭계수는 다양한 불규칙 궤도, 켐버, 주행속도, 자갈도상과 같은 주행조건에 의해 결정된다. 이와 같은 동적증폭계수를 해석하기위한 Newmark-${\beta}$ 기법과 Runge-Kutta기법을 적용하여 고속철 속도별과 경간별로 면밀하게 비교 분석하였다.