• Geotechnical Engineering
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• v.8 no.2
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• pp.5-20
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• 1992

The physical-based and lumped-parameter hydrologic groundwater flow model for predicting the rainfall-triggered rise of groundwater levels in hillside slopes is developed in this paper to assess the risk of landslides. The developed model consists of a vertical infiltration model for unsaturated zone linked to a linear storage reservoir model(LSRM) for saturated zone. The groundwater flow model has uncertain constants like soil depttL slope angle, saturated permeability, and potential evapotranspiration and four free model parameters like a, b, c, and K. The free model parameters could be estimated from known input-output records. The BARD algorithm is uses as the parameter estimation technique which is based on a linearization of the proposed model by Gauss -Newton method and Taylor series expansion. The application to examine the capacity of prediction shows that the developed model has a potential of use in forecast systems of predicting landslides and that the optimal estimate of potential 'a' in infiltration model is the most important in the global optimum analysis because small variation of it results in the large change of the objective function, the sum of squares of deviations of the observed and computed groundwater levels. 본 논문에서는 가파른 산사면에서 산사태의 발생을 예측하기 위한 수문학적 인 지하수 흐름 모델을 개발하였다. 이 모델은 물리적인 개념에 기본하였으며, Lumped-parameter를 이용하였다. 개발된 지하수 흐름 모델은 두 모델을 조합하여 구성되어 있으며, 비포화대 흐름을 위해서는 수정된 abcd 모델을, 포화대 흐름에 대해서는 시간 지체 효과를 고려할 수 있는 선형 저수지 모델을 이용하였다. 지하수 흐름 모델은 토층의 두께, 산사면의 경사각, 포화투수계수, 잠재 증발산 량과 같은 불확실한 상수들과 a, b, c, 그리고 K와 같은 자유모델변수들을 가진다. 자유모델변수들은 유입-유출 자료들로부터 평가할 수 있으며, 이를 위해서 본 논문에서는 Gauss-Newton 방법을 이용한 Bard 알고리즘을 사용하였다. 서울 구로구 시흥동 산사태 발생 지역의 산사면에 대하여 개발된 모델을 적용하여 예제 해석을 수행함으로써, 지하수 흐름 모델이 산사태 발생 예측을 위하여 이용할 수 있음을 입증하였다. 또한, 매개변수분석 연구를 통하여, 변수 a값은 작은 변화에 대하여 목적함수값에 큰 변화를 일으키므로 a의 값에 대한 최적값을 구하는 것이 가장 중요한 요소라는 결론을 얻었다.

• Journal of Korea Port Economic Association
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• v.25 no.4
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• pp.183-202
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• 2009

This study estimates the port waiting cost of international trade ports in Korea by an opportunity cost approach. In the next step, we present a method to assess the levels of port services by the average waiting cost of ships derived from the results of the first step. Because the port waiting cost reflects the social cost, it is difficult to use as a service indicator even though it is the decision support information for a particular port facility expansion. The percentages of waiting ships and time also are insufficient indicators to reflect only the quantitative aspects by the time. However, the average waiting cost of ships in this study can be utilized as a service indicator to reflect waiting time and the loss of economic value simultaneously. It is also very useful information for a shipper and a carrier to select a port. Based on the average waiting cost of ships in 2007, it is analyzed in order of lowest service ports sequentially such as Pyeongtaek-Dangjin, Pohang, Donghae, and Samcheonpo. It is different from the sequential order of ports by the port waiting cost such as Pohang, Incheon, Gwangyang, Pyeongtak-Dangjin, and Ulsan. The port waiting cost is to a port authority as a key indicator what the average waiting cost of ships is to a port user as a useful indicator to evaluate the levels of port services.

• Journal of Korean Academy of Nursing Administration
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• v.8 no.3
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• pp.431-439
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• 2002

Purpose : Nursing profession has been rapidly changed due to the development of bioscience and the change of medical service environment. Nursing profession that has been focused on only care giver's role like mother's in tradition, is required careful reflection new nursing role to cope properly to the change of medical service environment. In nursing profession, the concept of the role was used without an accurate definition, as a results, the concept of the role was mixed with the concept of the "activity", "job" and "function". Therefore, concept analysis of the role in nursing profession is needed to remove conceptual ambiguous and make confirm the true meaning of the role. Concept analysis is a strategy that examine the characteristics of a concept. It is a formal linguistic exercise to determine those defining attributes. The basic purpose of concept analysis is to clarify ambiguous concept in theory, and propose operational definition which reflects the theoretical base of the concept. Method : In this study, the concept of the role in nursing profession which was analyzed based on the steps of concept analysis by Walker & Avant(1988). Results : The attributes of the concept of the role in nursing profession are : 1. Basic factors to construct social structure. 2. Expected attitudes, values, behavior patterns according to the social status and position in social structure. 3. Perceptive attitudes, values, behavior patterns in order to social interaction. 4. Acquiring through continuous communication and learning. 5. Not fixative but changeable. The antecedents of the role in nursing profession are : 1. The social status and position which is possessed by a person. 2. Expected attitudes, values, behavior patterns according to the social status and position in social structure. 3. Acquiring through continuous interaction, communication, and learning process. And the consequences of the role in nursing profession are : 1. The role maintenance and the role expansion as a positive consequences. 2. The role conflict and the role loss as a negative consequences. Conclusion : Through this concept analysis, the concept of the role in nursing profession is defined as As basic factors to construct social structure, person's attitudes, values, behavior patterns which are expected from other social members according to person's social status and position, and perceived and acquired through continuous interaction, communication, and leaning process.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.17 no.3
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• pp.362-370
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• 2010

Purpose: In this study the present status of the practicum in Fundamentals of Nursing and test for student competency in nursing skills were surveyed. Method: Participants included 72 nursing schools. A structured questionnaire was used for data collection and SPSS 17.0 for data analysis. Results: Credits for Fundamentals of Nursing, credits for practicum and hours per credit were 2.93, 7.34, and 2.14 respectively. Number of students per practice unit, full time assistants and students per assistant were 28.6, 0.6, and 20.2 respectively. Utilization of CPX room and OSCE room for practice was 5.6%, and 9.7% respectively. Of the school, 32.0% included clinical practice in the practicum. 90.3% provided an open lab but only 48.4% had full-time assistants for these clinical practice areas. Testing for nursing skill competency was performed twice a semester in most schools. Utilization of standard patients and high fidelity models for testing was 8.3%, and 23.6% respectively. The test was thought to be inappropriate in 33.4% of the schools. Conclusions: The results suggest that to improve the outcomes, the practicum for Fundamentals of Nursing needs to be changed to include expansion of facilities and human resources, utilization of standard patients and high fidelity models and development of appropriate test methods.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.481-490
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• 2005

The aim of this study was to investigate the relationship between the C-factor and shrinkage strain values of composite resin and examine the strain values in different incremental filling techniques. The strain gauge method was used for measurement of polymerization shrinkge strain. Experiment was divided two step. In a first experiment, we compared with strain value in three different depth (2mm, 3mm, 4mm) and microhardness of each samples after 24hours were measured. In a second experiment, we examined the strain values in five different filling techniques(Group 1: bulk filling, Group 2: oblique incremental filling, Group 3: horizontal incremental filling, Group 4: vertical incremental filling, Group 5: lining of flowable resin and bulk filling) The results of the present study can be summarized as follows: 1. Composite resin in acrylic molds showed the initial expansion at the early phase of polymerization. 2. Contraction stress was not revealed significant difference between depth of 2mm and 3mm(P>0.05). 3. Contraction stress in sample of 4mm was showed the lowest value(P<0.05). 4. Microhardness of specimen was revealed more difference between upper and lower surface in depth of 4mm than 2 and 3mm(P<0.05). 5. Lining of flowable resin and bulk filling (Group 5) was showed the lowest contraction stress, Group 2 and 3 was showed the highest contraction stress(P<0.05). On the basis above results, the stress that result from the polymerization shrinkage, when incremental curing techniques are used, showed that there is no advantage in incremental placement and curing.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.744-750
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• 1998

Unlike common device, MEMS(micro-electro-mechanical system) device consists of very small mechanical structures which determine the performance of the device. Because of its small mechanical structure inside. MEMS device is very sensitive to thermal stress caused by CTE(coefficient of thermal expansion) mismatch between its components. Therefore, its characteristics are affected by material properties. process temperature. and dimensions of each layer such as chip, adhesive and substrate. In this study. we investigated the change of the thermal stress in the chip attached to a substrate. With computer-aided finite element method (FEM), the computer simulation of the thermal stress was conducted on variables such as bonding material, process temperature, bonding layer thickness and die size. The commercial simulation program, ABAQUS ver5.6, was used. Subsequently 3-layer test samples were fabricated, and their degree of bending were measured by 3-D coordinate measuring machine. The experimental results were in good agreement with the simulation results. This study shows that the bonding layer could be the source of stress or act as the buffer layer for stress according to its elastic modulus and CTE. Solder adhesive layer was the source of stress due to its high elastic modulus, therefore high compressive stress was developed in the chip. And the maximum tensile stress was developed in the adhesive layer. On the other hand, polymer adhesive layer with low elastic modulus acted as buffer layer, and resulted in lower compressive stress. The maximum tensile stress was developed in the substrate.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.581-586
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• 2005

High-performance concrete (HPC), which is particularly sensitive to self-desiccation, is required to be durable even in severe environmental conditions, i.e. costal area, cold district, etc. However, in recent years, some attention was particularly given to cracking sensitivity of high performance concrete at early age. It has been argued and demonstrated experimentally that such concrete undergoes autogenous shrinkage due to self-desiccation at early age under restrained condition, nd, as a result, internal tensile stress may develop, leading to micro cracking and macro cracking. This shrinkage-introduced crack produces a major serviceability problem for concrete structures. One possible method to reduce cracking due to autogenous shrinkage is the addition of expansive additive. Tests conducted by many researches have shown the beneficial effects of addition of expansive additive for reducing the risk of autogenous shrinkage-introduced cracking. However, the research on hydration model of expansion additive has been hardly researched up to now. This paper presents a study of the hydration model of Ettringite-Gypsum type expansive additive. As a result of comparing forecast values with experiment value, proposed model is shown to expressible of hydration of expansive additive.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.293-301
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• 2017

A Sub-kWe small-scale experimental test loop was manufactured to investigate characteristics of the supercritical carbon dioxide power cycle. A high-speed turbo-generator was also designed and manufactured. The designed rotational speed of this turbo-generator was 200,000 rpm. Because of the low expansion ratio through the turbine and low mass flowrate, the rotational speed of the turbo-generator was high. Therefore, it was difficult to select the rotating parts and design the turbine wheel, axial force balance and rotor dynamics in the lab-scale experimental test loop. Using only one channel of the nozzle, the partial admission method was adapted to reduce the rotational speed of the rotor. This was the world's first approach to the supercritical carbon dioxide turbo-generator. A cold-run test using nitrogen gas under an atmospheric condition was conducted to observe the effect of the partial admission nozzle on the rotor dynamics. The vibration level of the rotor was obtained using a gap sensor, and the results showed that the effect of the partial admission nozzle on the rotor dynamics was allowable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.795-805
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• 2011

The research on the immersive media technology is actively being done with the emergence of immersive services using immersive media, especially in the broadcasting industry and with the increased market demand for it. The industry which produces, transmits, processes and services the immersive contents is commonly called Immersive Media Industry. Immersive Media Industry has recently received attention as next-generation strategic industry with its high marketability and its high possibility of market expansion through convergence with other industry such as education, health, advertisement, travel and public service industry. As other advanccd country such as the U.S., Japan and Europe buckle down to take the innitiative in the immersive media industry, Korea government also begins to make plan to promote the immersive media industry. As above, immersive media industry is a cutting-edge convergence industry which embraces broadcasting, telecommunication and contents industry and it is rising as core growth engine industry. This article analyses the economic effects of immersive media industry through quantatitive method and evaluates the relations between the immersive media industry and the other related industries. As a result, the effect on production inducement of immersive media industry is 610.9 billion Korean Won; the effect on value-added inducement is 468.7 billion Korean Won; and it is measured that 3,258 job will be created by the immersive media industry.

• Journal of Science Education
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• v.43 no.3
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• pp.400-416
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• 2019

The purpose of this study is to find ways to improve education about safe medication use by investigating the current status of medication use by middle and high school students, and by evaluating their knowledge, attitudes, practices and education needs toward safe medication use. For this purpose, a survey was administered to 200 middle and high school students in Seoul and Gyeonggi Province. Over the past year, 92.0% and 57.5% of respondents used over-the counter drugs and prescription drugs at least one time, respectively. Regarding the experience of education on safe medication use, 34.0% of respondents have been educated more than once since their admission to middle school. The overall mean score of knowledge·attitude·practice (KAP) toward safe medication use was 3.79, but the mean score of practice scope was relatively lower than the others. Moreover, there were no significant differences in KAP scores for safe medication use by school grade or educational experience. Based on these findings, we suggest further studies regarding 1) expansion and differentiation of education content on safe medication use, 2) transition of education method to outcome-based education approach, and 3) inclusion of education on safe medication use in the regular curriculum of middle and high schools.