• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.511-511
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• 2017

하천에서 홍수 예방 및 가뭄재해 방지를 목적으로 최근 4대강 살리기 사업이 수행되었다. 특히, 안정적인 용수공급 및 다양한 수재해 피해를 최소화하기위해 다기능보가 설치되었다. 설치된 보는 고정보와 가동보로 구분되며 평상시에는 고정보를 넘어가는 월류흐름이 발생하며 홍수 시에는 추가적으로 가동보를 개방하여 오리피스 흐름이 발생한다. 최근 기후변화로 인해 집중호우가 빈번히 발생하며 이는 보 주변에서 빠르고 복잡한 흐름을 유발하게 된다. 이러한 흐름특성은 보하류의 세굴문제뿐만 아니라 물받이와 바닥보호공의 안전성에 영향을 미칠 수 있다. 본 연구에서는 영상기법을 활용하여 도수가 발생하는 조건에서 고정보 하류의 물받이공 및 바닥보호공에 난류흐름특성 및 압력분포를 분석하였다. 길이 8.0 m, 폭 0.3 m를 갖는 개수로에서 실험을 수행하였으며 0.2 m 높이의 고정보는 상류경계로부터 3.0 m지점에 위치하였다. 보 하류부에서 유속성분은 비접촉식 유속측정 기법인 입자영상유속계(Particle Image velocimetry, PIV)와 기포흐름을 측정할 수 있는 기포영상유속계(Bubble Image velocimetry, BIV)를 적용하였다. 그러므로 기포 존재유무와 관계없이 보 하류부 구간에 대한 유속장 성분을 취득하였다. 도수흐름은 물받이공 및 바닥보호공 영역의 바닥면을 따라 빠른 유속을 갖는 제트류가 발생하고 수면과 바닥으로 강한 진동이 발생하여 불안정한 흐름이 야기된다. 바닥면에 작용하는 압력을 측정하기 위해 흐름방향을 따라 피에조미터를 설치하였고 압력수두 분포를 초고속카메라로 촬영하여 그 특성을 분석하였다. 실험을 결과를 통해 보 하류부에 영향을 미치는 인자를 도출하였으며 향후 보 설계기준에 반영할 수 있을 것으로 기대된다.

• Journal of the Korean Society for Railway
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• v.11 no.5
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• pp.489-498
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• 2008

In general, deflection limit criteria of bridge design specifications have been considered based on static serviceability and structural stability. Dynamic serviceability induced from bridge vibration actually has not been included in the criteria. Thus, it is necessary for deflection limit to be considered in order to check dynamic service- ability on bridge vibration. In this study, The allowable displacement of Korea Railway Bridge Design Specifications is compared to the frequency domain comfort limit and analyzed france code and japanese code. Korea Railway Bridge Design Specifications is regulated based on the train speed. Such is because the vibration time duration is partly considered. but this criteria is not satisfied with comfort limit. and, it is estimated to be capable to provide deflection limit considering dynamic serviceability. In order to evaluate the dynamic serviceability of various types of railway bridges in current public were selected and their dynamic signals were measured. and the result of the bridge-train interaction analysis according to the changes in bridge stiffness was compared to the comfort limit to suggest the stiff-ness limit to the dynamic serviceability, which should conveniently be applied at the field.

• Nuclear Engineering and Technology
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• v.17 no.1
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• pp.25-33
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• 1985

The main purpose of this work is to investigate the effects of the wall thickness, the ultrasonic frequency, and the acoustic impedance of wall material on the liquid-film thickness measurement by an ultrasonic pulse echo method. A series of liquid-film thickness measurements in a horizontal air-water stratified system was performed employing a plate-type and a tube-type test sections. Measurements were repeated changing (1) the wall thickness of the test section and (2) the transducer frequency. Also, in an effort to improve the accuracy of the measurement and to exam me the effect of acoustic impedance of wall material on the measurement by an ultrasonic technique, two different stand-off rods, one made of stainless steel and the other polyacrylate, were used in the liquid-film thickness measurement. These experimental results are discussed and compared with the actual film thicknesses.

• Korean Journal of Psychosomatic Medicine
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• v.24 no.1
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• pp.61-65
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• 2016

Currently, a variety of Information and Communication Technology(ICT) is being broadly utilized for mental health. Especially, mobile application is one of the effective ICT, and several applications have been developed after the spread of smartphones. The mobile-based mental health has several strengths, such as better treatment accessibility and easier check-ups of symptoms or daily activities by real-time monitoring. Better follow-ups of treatment course, more customized feedback and better transportability enable patients to be more adherent. However, there are some limitations of mobile technology about the mental health, such as technical troubles of electric errors, data safety problems and personal information extrusion. Therefore, full considerations should be given during the development and provision of the technology. Most of all, mental health specialists should actively participate in the development process by incorporation of evidence-based experiences and assurance of good clinical qualities.

• Journal of Digital Convergence
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• v.19 no.4
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• pp.457-466
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• 2021

This study was a systematic review that aimed to assess the effectiveness of educational programs for members of multicultural families. Therefore, 21 studies from domestic databases - RISS, KISS, NDSL, DBia, and nanet - were analyzed and the data were compiled and encoded by three researchers. Regarding the characteristics of the educational programs for multicultural families, 12 programs were developed for children, eight, for parents, and one, for both parents and children. While most intervention programs included topics on health, responsive care, and early education, none included topics on nutrition and safe space or targeted all members of multicultural families. This study identified the need for developing educational programs for all members of multicultural families and for developing and evaluating programs that can address, on a theoretical basis, the problems encountered by multicultural families.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.465-472
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• 2021

Prior to the actual flight test of the separation-reintegration situation of fixed-wing mother and child UAVs in the air, it is necessary to verify the flight control system of child UAV through simulations. In this paper, we build a simulation environment for the development of a child UAV flight control system in a lab environment based on the wake turbulence of X-Plane. To this end, the aerodynamics analysis of child UAV was performed, and Simulink was used to simulate aircraft, and X-Plane was utilized to implement visualization, wind, gusts, and mother UAV movements. The simulation environment built by performing simulated proximity flights was verified by applying the guidance and control algorithm to the child UAV model within Simulink. Furthermore, the flight results confirm the area in which the child UAV can safely fly from the rear of the mother UAV.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.423-428
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• 2019

As areas of ICT devices expand due to development of fourth industry, Smart Jewelry is being released. Jewelry is not only a fashion tool to dress up the human body as it merges with the functional aspects of smart devices, but it also delivers the information needed to improve users' living conditions and the interaction of the information needed is likely to be expanded. Although wearable Jewelry is not widely popular with consumers due to its recognition that it is a Smartphone aid and technical limitations, it needs to be ultra-smallized and improved in design. By analyzing emotional types according to design, materials, and colors, focusing on the current wearable jewelry products, the company aims to contribute to enhancing the value of creative smart jewelry by thinking about how smart jewelry will stimulate people's emotions.

• Journal of Platform Technology
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• v.6 no.4
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• pp.69-77
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• 2018

In the case of personal information files containing personal information, there is insufficient awareness of personal information protection in end-point areas such as personal computers, smart terminals, and personal storage devices. In this study, we use Diffie-Hellman method to securely retrieve personal information files generated by web crawler. We designed SEED and ARIA using hybrid slicing to protect against attack on personal information file. The encryption performance of the personal information file collected by the Web crawling method is compared with the encryption decryption rate according to the key generation and the encryption decryption sharing according to the user key level. The simulation was performed on the personal information file delivered to the external agency transmission process. As a result, we compared the performance of existing methods and found that the detection rate is improved by 4.64 times and the information protection rate is improved by 18.3%.

• Journal of Digital Convergence
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• v.16 no.11
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• pp.1-15
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• 2018

The purpose of this study is to analyze bibliographic information of Busan and other cities' reports for urban development initiative and identify the strategic fields for future smart city plan. Text mining method is used in this study to extract keywords and identify the characteristics and patterns of information in urban development reports. As a result, in earlier stage, Busan city focused on service creation for industrial development but there are lack of discussions on the linkage of information systems with ICT technology. However, recent urban planning in Busan contained various contents related to integrated connections of infrastructure, ICT system, and operation management of city in the specific fields of traffic, tourism, welfare, port/logistics, culture/MICE. This results of study is expected to provide policy implications for planning the future urban initiatives of smart city development.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.291-294
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• 2014

By building an environment that can utilize big data, many companies are interested in the cloud computing technology that has increased its popularity recently. By developing cloud environments from existing virtual environments, in the process, we discovered a variety of security vulnerabilities such as management, virtual machines, hypervisors, hardware etc. The security techniques from administrative aspects in the cloud environment provide the environment which can securely store data by the identification and control of security threats. In this paper, we investigate a list of companies which supports the cloud services and the types of services, and analyze the security threats according to the administrative aspects in the cloud environment. In addition, we suggest the direction for future improvements by investigating accidents or incidents which occurred recently.