• KSTLE International Journal
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• 제3권1호
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• pp.60-67
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• 2002

Wear on the tube-to-spring contact is investigated experimentally, The vibration of the tube causes the wear while the springs support it As for the supporting conditions, the contacting normal farce of 5 N,0 N and the gap of 0.1 mm are applied. The gap condition is for considering the influence of simultaneous impacting and sliding on wear. The wear volume and depth decreases in the order of the 5 N,0 N and the gap conditions. This is explained from the contact geometry of the spring, which is convex of smooth contour, The contact shear force is regarded smaller in the case of the gap existence compared with the other conditions. The wear mechanism is considered from SEM observation of the worn surface. The variation of the normal contact traction is analysed using the finite element analysis to estimate the slip displacement range on the contact with consulting the fretting map.

• 한국압력기기공학회 논문집
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• 제7권4호
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• pp.51-56
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• 2011

Steam generator is one of the main equipments that affect safety and long term operation in nuclear power plants. Fluid flows inside and outside of the steam generator tubes and induces vibration. To prevent the vibration the tubes are supported by AVB (anti vibration bar). When the steam generator tube contact to AVB, it is damaged by the accumulation of wear and corrosion. Therefore studies are required to determine the effects of the gap between the steam generator tube and AVB. In order to obtain the stress and the displacement distributions of the steam generator tube, three dimensional finite element analyses were performed by using the commercial program ANSYS. Using the calculated the stress and the displacement distributions, the static residual strength of the steam generator tube can be evaluated. The results show that the stress and displacement of the steam generator tube increase significantly compared with the results from a zero-gap model.

• Nuclear Engineering and Technology
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• 제43권5호
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• pp.447-458
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• 2011

This paper proposes an approximated contact force model to identify the nonlinear behavior of a fuel rod with gap supports; also, the numerical prediction of interfacial forces in the mechanical contact of fuel rods with gap supports is studied. The Newmark integration method requires the current status of the contact force, but the contact force is not given a priori. Taylor's expansion can be used to predict the unknown contact force; therefore, it should be guaranteed that the first derivative of the contact force is continuous. This work proposes a continuous and differentiable contact force model with the ability to estimate the current state of the contact force. An approximated convex and differentiable potential function for the contact force is described, and a variational formulation is also provided. A numerical example that considers the particularly stiff supports has been studied, and a fuel rod with hardening supports was also examined for a realistic simulation. An approximated proper solution can be obtained using the results, and abrupt changes from the contacting state to non-contacting state, or vice versa, can be relieved. It can also be seen that not only the external force but also the developed contact force affects the response.

• International Journal of Computer Science & Network Security
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• 제24권3호
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• pp.113-124
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• 2024

One of the goals of the Saudi Arabia 2030 vision is to ensure full employment of its citizens. Recruitment of graduates depends on the quality of skills that they may have gained during their study. Hence, the quality of education and ensuring that graduates have sufficient knowledge about the in-demand skills of the market are necessary. However, IT graduates are usually not aware of whether they are suitable for recruitment or not. This study builds a prediction model that can be deployed on the web, where users can input variables to generate predictions. Furthermore, it provides data-driven recommendations of the in-demand skills in the Saudi IT labor market to overcome the unemployment problem. Data were collected from two online job portals: LinkedIn and Bayt.com. Three machine learning algorithms, namely, Support Vector Machine, k-Nearest Neighbor, and Naïve Bayes were used to build the model. Furthermore, descriptive and data analysis methods were employed herein to evaluate the existing gap. Results showed that there existed a gap between labor market employers' expectations of Saudi workers and the skills that the workers were equipped with from their educational institutions. Planned collaboration between industry and education providers is required to narrow down this gap.

• 한국측량학회지
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• 제39권5호
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• pp.321-328
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• 2021

This study considered measures to support the establishment of surveying and spatial information in preparation for the unification of South and North Korea and the subsequent construction of national infrastructure. The organization identified and analyzed spatial information about North Korea, road and railway-oriented SOC construction projects, and examined the applicability of the latest technologies to narrow the technical gap with North Korea and quickly establish land spatial information. To prepare a support process appropriate for the situation in North Korea, technical and human support details and considerations were reviewed through a case analysis of spatial information construction for developing countries. In addition, the main result was "Presenting Efficient Utilization of Human Resources and Equipment for the Establishment of Spatial Information in North Korea," establishing an efficient utilization plan for the human resources and equipment needed in the support process based on technology support. It is expected that the South Korean government will minimize the negative impact on future land infrastructure construction by first conducting research in inter-Korean economic cooperation and national infrastructure construction and establishment of spatial information construction plans.

• 해양환경안전학회지
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• 제24권6호
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• pp.803-809
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• 2018

갭색법(gap & sag method)은 선박 건조과정에서 축을 조립하기 전 최종적으로 축이 축계정렬 설계치와 동일한 위치에 거치되었는지의 여부를 확인하기 위해 사용되고 있는 방법이며, 조립 전 프로펠러축을 기준축으로 하여 양 축의 플랜지에서 축 자중에 의해 발생하는 갭색값을 통해 나머지 축계의 위치를 순차적으로 확정해 나간다. 만일 설계치와 다르게 기준축이 거치되는 경우 연쇄적으로 나머지 축의 거치에 영향을 주게 된다. 또한, 축 조립 후 검증과정에서 측정된 베어링 반력이 설령 설계치를 만족하더라도 선미관 후부측에서의 프로펠러축과 베어링간 상대적경사각을 추정할 수 없게 됨으로써 결과적으로 축계의 안정성에 부정적인 영향을 미칠 수 있다. 이러한 문제를 해결하기 위하여 본 연구에서는 실제 선미관 베어링 발열 및 개방검사 사례를 통해 선미관 베어링 유효지지점에 관한 이론계산 및 실측치분석 연구를 수행하고 이를 바탕으로 축계 정렬오차를 최소화하기 위한 축계 시공방법을 제안하였다.

• 수산해양교육연구
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• 제22권1호
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• pp.52-66
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• 2010

The purpose of this study is to identify the recognition and some solutions of academic achievement gap among academic high schools of four equalization cities' persons concerned in Gyeongsangnam-do. The persons concerned are designated to pupils, parents and teachers of secondary schooling. To accomplish the purpose of this study, the following two questions were asked: (i) How serious do they recognize academic achievement gap among academic high schools? (ii) What kind of solutions do they prefer in order to reduce or dissolve academic achievement gap among academic high schools? The survey subjects of this study were 4,192 persons. They consisted of 2,428 pupils, 1,173 parents and 591 teachers of secondary schools. The contents of the questionnaire were made of the details of the above two questions. Frequencies, percentage, $x^2$ and F test were mainly applied to the statistical analyses. The findings of this study may be summarized as follows. First, half of the subjects recognized the seriousness of academic achievement gap among academic high schools in general. Parents were higher than teachers and teachers were higher than pupils in recognizing the seriousness of this issue. Secondly, they recognized that radical change of current allocation ways, incentives to competent teachers, and financial support, administrative counseling for unpopular high schools etc. were some potent alternatives to this issue.

• 산업융합연구
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• 제22권5호
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• pp.39-48
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• 2024

코로나19로 인하여 개학연기부터 장기화된 온라인 원격수업으로 학습 손실과 교육격차에 대한 연구는 많이 진행되었으며, 대부분 교육격차 현상에 대한 연구가 주를 이루었다. 향후 이와 같은 팬데믹 상황이 온다면, 교육격차 해소를 위한 근본적인 정책이 필요하다. 근본적인 해결책은 교육격차 현상에 대한 이해뿐만 아니라 그 현상의 이면의 구조를 파악해야 한다. 따라서 본 연구는 구조주의 관점에서 코로나19로 인한 교육격차를 시스템사고의 원형으로 모델링하고 그 구조를 파악하고자 하였다. 그리고 기존의 교육격차 해소를 위한 정책들로 발생한 의도하지 않은 결과를 살펴보았다. 향후 유사한 재난상황에 대응하기 위해 본 연구의 구조를 기반으로 디지털 격차해소를 위한 정책, 기초학력 지원, 원격수업에 대한 품질 향상, 자기주도 학습에 대해 논의하였다.

• 한국전자거래학회지
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• 제9권3호
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• pp.145-154
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• 2004

객체지향 및 컴포넌트지향 소프트웨어 개발 방법론의 클래스의 도출은 개발하려는 소프트웨어의 전체 품질을 결정하는데 중요한 요소이다. 각 방법론에서는 이 부분에 대해 클래스의 정의와 도출하는 방법을 설명하고 있지만 초보 분석자들이 활용하기는 어려운 점이 많다. 그 중, 개념적 갭(conceptual gap)으로 인한 문제는 클래스 도출에 가장 큰 영향을 미친다. 연구에서는 이런 부분을 보완하기 위한 장치로써 세가지 다이어그램을 제안한다. 요구분석과정의 결과를 도식적으로 정리하여 클래스 도출을 보완하기 위한 도구로 정보다이어그램(Information Diagram), 행위다이어그램(Behavior Diagram) 그리고 관리다이어그램(Management Diagram)이다. 세 다이어그램은 시스템의 관련자(stakeholder)가 시스템에 어떤 서비스를 요구하는가에 대한 관점으로 필요한 정보를 찾고, 그에 포함될 수 있는 세부 행위를 분석하고, 누가 이 서비스에 대한 책임이 있는가의 명세이다. 본 연구에서 제안하는 다이어그램들은 기존의 소프트웨어 개발 방법에서 클래스를 도출하는 과정에 활용할 수 있다.

• 한국기계가공학회지
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• 제16권4호
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• pp.38-45
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• 2017

A finite element analysis-based approach which investigates the causes of the breakdown in the outer ring of the choke at hot rod rolling mill is presented. Two-dimensional drawings of the whole vertical-type mill stand are transformed into three-dimensional CAD models. Non-linear elasto-plastic deformation analysis of material at the roll gap is performed for computing roll force and torque of the work roll. Then, the reaction forces of the bearing rings together with a set of roller bearings that support the work roll are obtained by means of rigid body motion analysis. Finally, stress behaviors in the bearing rings together with a set of roller bearings that support the work roll are investigated by linear elastic analysis. Results reveal that stress at the contact area between the outer ring and roller bearing is extraordinary high when an internal gap between an external surface of the outer ring and the internal surface of the chock due to wear of the inside of the chock occurs.