• 한국해양공학회지
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• 제16권2호
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• pp.60-66
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• 2002

The remote measurement system(RMS) as a new experimental method is limited in its application to crack measurement at elevated temperatures because of the oxide layer on the specimen surface. Since TiAIN and Cr coating layers have a high resistance to oxidation and wear, this paper proposed a TiAIN and Cr coating technique for specimens to facilitate the measurement of crack growth behavior using RMS. To investigate the effects of the coating layer, tension and fatigue tests were carried out at room temperature and at $538^{\circ}C$. The test material was 1Cr-1Mo-0.25V steel which is widely used as a turbine rotor material. From the experimental results, it was found that the mechanical properties of the TiAIN and Cr coated specimens were similar to those of the substrate. Accordingly, the TiAIN and Cr coated layer had hardly any influence on the fatigue crack propagation.

• 한국안전학회지
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• 제16권3호
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• pp.7-11
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• 2001

In this study, specimens were classified four welded specimens and a base metal to investigate fatigue life and crack growth rate of pure titanium welding materials, and Ti was used in turbine equipment of nuclear power generation, etc. The summarized results are as follows; 1) Specimen-2 was bigger 712% than base metal, when it was compared with other welding materials, 2) As the result of specimens data, specimen-2 crack behavior rate res lower 30 times than base metal, and so total fracture life was very influenced by it, 3) Notch tip of Specimen-2 was offsetted 6.7mm from boundary H.A.Z, and if formed 25% in total fracture length, 4) As the considering of da/dN and $\Delta$K, Paris' law is incongruous in this study, because fro inclines nsf on one date.

• 한국해양공학회지
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• 제8권2호
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• pp.115-123
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• 1994

Under variable amplitude loading conditions, retardation or accelerated condition of fatigue crack growth occurs with every cycle, Because fatigue crack growth behavior varied depend on load time history. The modeling of stress amplitude with storm loading acted to ships and offshore structures applied this paper. The crack closure behavior examine by recording the variation in load-strain relationship. By taking process mentioned above, fatigue crack growth rate, crack length, stress intensity factor, and crack closure stress intensity factor were obtained from the stress cycles of each type of storm ; A(6m), B(7m), C(8m), D(9m), E(11m) and F(15m) which was wave height. It showed that the good agreement with between the experiment results and simulation of storm loads. So this estimated method of crack propagtion rate gives a good criterion for the safe design of vessels and marine structure.

• 한국안전학회지
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• 제17권4호
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• pp.11-18
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• 2002

We proposed a new experimental method which is required to easily observe the growth behavior of fatigue cracks. In the proposed method, the image data of cracks were stored into the computer while the cyclic loading was interrupted. After testing, crack length was determined using an image processing software which was developed by authors. By comparing the data measured by the image processing system with those by the manual measurement with a microscope, the effectiveness of the image processing system was established. If the proposed method is used to monitor and observe the crack growth behavior automatically, the time and efforts for fatigue test could be dramatically reduced.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.81-84
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• 2006

To investigate the characteristics of water droplet on the gas diffusion layer from both upper-view and side-view of flow channel, a rig test apparatus was designed and fabricated with L-shape acryl plate in a $1mm{\times}1mm$ micro-channel. This experimental device is used to simulate the single droplet growth and its transport process under fuel cell operating condition. As a first step, we investigated the growth and transport of single water droplet with working temperature and air flow velocity. The contact angle and its hysteresis of water droplet at departing moment are measured and analyzed. It is expected that this study can provide the basic understanding of liquid water droplet behavior in gas flow channel and GDL interface during the PEM fuel cell operation.

• 한국표면공학회지
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• 제44권3호
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• pp.75-81
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• 2011

Growth behaviors of iron-nitride on S45C steels at low pressure gas nitriding were examined. Surfaces of the steels covered with fine and porous oxide during the pre-oxidation using $N_2O$ gas. Well faceted particles connected with them were observed after 1 min nitriding. They grew steadily and filled inter-pores during additional nitriding process. From the X-ray diffraction analysis, ${\gamma}'$-iron nitride was dominantly formed at the initial stage but the amount of ${\varepsilon}$-iron nitride was rapidly increased as nitriding treatment time. The porous layer was formed on the particles and thickened up to half of nitride layer after 60 min nitriding. The observed growth behaviors were discussed in internal stress related with volume expansion involved in transforming from iron to iron-nitrides.

• Child Health Nursing Research
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• 제8권4호
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• pp.414-421
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• 2002

The purpose of this study is to analyze the concept of caretaking behavior for children. This study adopts the methode of Walker and Avant in analysis. Based on the results of the study, the attributes, precedents, and consequences of caretaking behavior for children are follows ; 1. The affirmative attributes of caretaking behavior are affection binding, nutritional guidance, education, caring, protection moral training and acquisition of parents' role. The negative attributes of caretaking behavior are inconsistent moral training, incapability of affection binding and overprotection. 2. The precedent of caretaking behavior are postpartum contact with their babies, cognizance capacity of child-caretaking, economic support, level of preparation for child-caretaking and self-consciousness as parents. 3. The affirmative consequences of caretaking behavior are promotion of child growth and development, formation of maternal-infantile attachment, development of children sociality, satisfaction of parental role and reinforcement of relationship between the members of family. The negative consequences of caretaking behavior are burden and conflict to parental role, children's illness, role conflict and role stress among the members of the family and family breaking up.

• 한국결정성장학회지
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• 제22권3호
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• pp.115-121
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• 2012

사파이어 단결정은 GaN계 화합물 증착이 용이하여 고휘도의 청색을 구현하기 위한 LED(Light Emitting Diode)용 기판으로 크게 각광받고 있다. 공업용 사파이어의 제조 방법으로는 Kyropoulos법, Czochralski법 HEM(Heat Exchager Method)등 다양한 방법이 시도되고 있으며, 그 중 Kyropoulos법은 고품질의 대구경 사파이어 단결정 성장이 가능한 대표적인 방법으로 알려져 있다. 그러나 Kyropoulos 공정의 특성상 결정성장로 내에서 용융 사파이어의 유동장이 단결정의 최종 품질을 결정하는데, 유동장의 변화와 이에 따르는 결정성장 거동을 관찰하기가 어렵다는 단점이 있다. 대구경화와 동시에 고품질의 사파이어 단결정을 생산하기 위해서는 성장로내의 유동장 해석을 통해 결정 성장조건을 최적화 하는 것이 필요하다. 본 연구에서는 유한요소법을 기반으로 한 전산유동해석을 통해 Kyropoulos 성장로 내의 도가니 형상의 종횡비(h/d)에 따른 용융 사파이어의 대류거동을 관찰하여 도가니의 형상이 단결정 성장에 미치는 영향을 분석하였으며, 성장로의 설계시 도가니의 종횡비를 작게 고려하면 용융 사파이어의 대류속도를 늦추고 계면의 convexity를 줄여 사파이어 단결정의 품질향상에 도움이 된다는 결과를 얻었다.

• 보건행정학회지
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• 제24권2호
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• pp.191-202
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• 2014

Background: The organizational citizenship behavior is generally known as the important factor relevant to the organizational effectiveness. This research examined the mediating effect of the organizational citizenship behavior of hospital employees on the organizational effectiveness. Methods: Data were collected from 1,112 employees located in city of Seoul, Kyunggi and Chungnam province through self-administered questionnaires. Collected data were analyzed using IBM SPSS ver. 20.0, frequency analysis, t-test, analysis of variance, regression analysis, and path analysis. The main findings of the study are as follows. Results: First, it was found that many characteristics variables of personality, job, and relationship together affected organizational citizenship behavior of hospital employees. Especially, the following variables of negative affectivity, desire for growth, job value, job significance, and job security were found to have significant effect on the organizational citizenship behavior of hospital employees. Second, the results of path analysis showed that, through the mediating effect of organizational citizenship behavior, personality variables of positive and negative affectivity, and desire for growth, job characteristics variables of job value, job significance, and job security, and relationship variables of organizational support and task interdependence, had significant total effects on the level of job satisfaction of hospital employees. Conclusion: As a result, the organizational citizenship behavior seems to have both direct and indirect effects on the organizational effectiveness of hospital employees. Based on above findings, some theoretical and practical implications were discussed.

• 한국결정성장학회지
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• 제9권6호
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• pp.558-562
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• 1999

승화 성장법을 적용하여 성장된 6H-SiC 결정에 대하여, KSV 이론과 성장 계면에서의 미사면(vicinal plane)상의 step 성장 양상을 근거로 하여, 성장 계면에서의 물질 흡착의 거동과 결함의 생성간의 상호 관계를 고찰하고, micropipes와 내부 결함의 생성 원인을 논하였다. micropipe와 면결함등의 결함들은 ledge 혹은 kink에 침입된 불순물에 의하여 step 성장의 진행이 방해받는 부분에 형성되었다. 따라서, SiC 결정에서 이들 결함의 생성은 SiC 결정 성장 계면에 형성되는 결정학적 step 성장면과 분자 또는 원자들의 격자 이동에 관련이 있음을 알 수 있었다.