• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.594-600
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• 2016

The present study numerically investigated the gas leakage characteristics in a simplified underground combined cycle power plant. The effect of obstacles near a crack location on the gas concentration in the confined space was analyzed by using the lower flammable limit (LFL) of methane gas. When the jet flow was close to the vertical walls, the longitudinal leakage distance increased by about 60% (when an obstacles was present) compared to the case without any obstacle, because these obstacles prevented transverse flows. In addition, when an air filter was installed near to the trajectory of the gas flow, the longitudinal leakage distance was similar to the distance between the crack and obstacle, whereas the transverse leakage distance increased up to 8 times compared to the case without any obstacle. As the jet flow impacts on the obstacle and changes its direction, the gas flows recirculate. Therefore, it is necessary to consider the effect of the structure and facility locations on the trajectory of the jet flow to propose an accident prevention system in confined spaces.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.235-246
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• 2008

Service-Oriented Architecture (SOA) is emerging as an effective approach for developing applications by dynamically discovering and composing reusable services. Generally, the benefits of SOA are known as low-development cost, high agility, high scalability, business level reuse, etc. However, a representative problem for widely applying SOA is the performance problem. This is caused by the nature of SOA such as service deployment and execution in distributed environment, heterogeneity of service platforms, use of a standard message format, etc. Therefore, performance problem has to be overcome to effectively apply SOA, and service performance has to be measured precisely to analyze where and why the problem has occurred. Prerequisite for this is a definition of a quality model to effectively measure service performance. However, current works on service performance lacks in defining a practical and precise quality model for measuring performance which adequately addresses the execution environment and features of SOA. Hence, in this paper, we define a quality model which includes a set of practical metrics for measuring service performance and an effective technique to measure the value of the proposed metrics. In addition, we apply the metrics for Hotel Reservation Service System (HRSS) to show the practicability and usefulness of the proposed metrics.

• Korean Journal of Optics and Photonics
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• v.29 no.1
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• pp.19-27
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• 2018

A change in object distance would generally change the magnification of an optical system. In this paper, we have proposed and designed a double-Gauss optical system with a fixed magnification and image surface regardless of any change in object distance, according to moving the lens groups a little bit to the front and rear of the stop, independently parallel to the direction of the optical axis. By maintaining a constant size of image formation in spite of various object-distance changes in a projection system such as a head-up display (HUD) or head-mounted display (HMD), we can prevent the field of view from changing while focusing in an HUD or HMD. Also, to check precisely the state of the wiring that connects semiconductor chips and IC circuit boards, we can keep the magnification of the optical system constant, even when the object distance changes due to vertical movement along the optical axis of a testing device. Additionally, if we use this double-Gauss optical system as a vision system in the testing process of lots of electronic boards in a manufacturing system, since we can systematically eliminate additional image processing for visual enhancement of image quality, we can dramatically reduce the testing time for a fast test process. Also, the Gaussian bracket method was used to find the moving distance of each group, to achieve the desired specifications and fix magnification and image surface simultaneously. After the initial design, the optimization of the optical system was performed using the Synopsys optical design software.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.7
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• pp.191-198
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• 2021

Since the size of training dataset become large and the model is getting deeper to achieve high accuracy in deep learning, the deep neural network training requires a lot of computation and it takes too much time with a single node. Therefore, distributed deep learning is proposed to reduce the training time by distributing computation across multiple nodes. In this study, we propose hybrid allreduce strategy that considers the characteristics of each layer and communication and computational overlapping technique for synchronization of distributed deep learning. Since the convolution layer has fewer parameters than the fully-connected layer as well as it is located at the upper, only short overlapping time is allowed. Thus, butterfly allreduce is used to synchronize the convolution layer. On the other hand, fully-connecter layer is synchronized using ring all-reduce. The empirical experiment results on PyTorch with our proposed scheme shows that the proposed method reduced the training time by up to 33% compared to the baseline PyTorch.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.371-377
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• 2018

Navigational equipment standardization mode is a function which is used to standardize key functions, screen display and operation method of major navigation equipment. This is aimed towards to quickly and accurately checking information relevant for safe navigation. Currently, the International Maritime Organization is working on the development of guidelines for the application of navigational equipment in the standardized mode to the task of NCSR Sub-Committee. This study was conducted to investigate users' opinions and preferences in the application of standardization modes and to reflect them in the development of guidelines. In addition, the test program was designed to investigate user preferences for ECDIS among the navigational equipment, such as the types of information and functions that are necessary or preferentially required to perform navigational duties, and the screen configuration. In the study, 333 preference surveys were conducted in 35 countries using a web - based test program. ECDIS users confirmed the content and screen layout of their preferred ECDIS information when conducting navigation duty. The results of the study are significant as they contribute to the development of effective guidelines by presenting user requirements to be considered in the standardization mode.

• 한국노년학
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• v.37 no.2
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• pp.293-308
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• 2017

This study aims to examine Life Managers for Elderly People Living Alone (LMEPLAs) in Seoul regarding their traumatic experience and the status of their posttraumatic stress disorder and also how they are coping with it in order to find out ways to improve it. As a study method, we investigated LMEPLAs in Seoul through a self-administered survey regarding whether they had faced any traumatic experience, types of their traumatic experience, diagnosis on posttraumatic stress, and the status of their coping with traumatic experience. According to the study results, 186 respondents (37.57%) have been found to indicate either partial or complete posttraumatic stress symptoms, but the status of their coping with it is very poor. The followings are the results of our discussion. First, it is needed to find out life managers suffering from posttraumatic stress disorder and build up a system to manage them consistently. Second, it is necessary to vitalize education about traumatic experience and posttraumatic stress management. Third, it is urgently needed to build up a system to support life managers who have faced any traumatic experience or been diagnosed to have posttraumatic stress disorder. Fourth, it is demanded to cultivate and arrange experts equipped with specialized knowledge and technique. Fifth, it is needed for them to build a network with medical institutes to receive a prompt diagnosis and specialized treatment.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.3
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• pp.51-64
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• 2019

Mt. Geumgang has been a scenic spot representing the Korean peninsula since the Joseon Dynasty, and became a symbol of inter-Korean exchanges with the Gaesong Industrial Complex after the division of the South and North. Mt. Geumgang Tour Course is divided into the Inner-Geumgang (Naegeumgang) and the Outer-Geumgang (Oegeumgang). It was common for the Mt. Geumgang tour route during the Joseon Dynasty and the Japanese Imperialization period to enter the Inner-Geumgang, near Seoul, and come to the East Sea through the Outer-Geumgang. However, the tour route starting from Goseong was utilized for the Mt. Geumgang tour course operated by Hyundai. Because North Korea opened only the Outer-Geumgang area. North Korea has only opened some of its tour courses to Hyundai, but if Geumgang tourism is resumed in the future, there is a high possibility that it will be opened further, such as opening some sections of the Inner-Geumgang in 2007. In this case, it is necessary to connect additional transportation networks to access Inner-Geumgang from South Korea. The best alternative was the restoration of the Mt. Geumgang Railway. However, considering the fact that the reconstruction of the Mt. Geumgang Railway can not be completed due to the construction of the Imnam Dam, it is the most realistic alternative to restore Route 31 connecting Yanggu and Geumgang-eup. As a result of the analysis of road connecting Inner-Geumgang, three routes were confirmed. All of which were adjacent to the existing National Route 31. These routes passing through Dutayeon and Mundeung-ri and joining the Route 31 from Inje. Considering road length, topography characteristics, and military facility layout, it seems that the connection of 'Dutaeyun - Mundeung - Geumgang' is a realistic alternative connecting from South Korea to Inner-Geumgang.

• The Korean Journal of Archival Studies
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• no.31
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• pp.43-93
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• 2012

The quality of human resources is critical element which promote efficiency in the community management. Each country all of the world is developing national competency standards to exploit them on human resources management. In response to this trend, the field of records management need to develop competency standards and to build human resources. Although each agency is placing qualified record manager and operating archives organization. growth and development is needed on this field. Under these circumstances, examining requirement for records management competency and using them is a task of great significance on the side of strengthening specialist and normalizing archives operation. This study suggests procedures and methodology competency standards enable to be exploited in entire fields of records management including private sectors as well as public sectors. Furthermore, as for procedures of suggesting measures for developments, cases of procedures of stand designs are shown, effectively verifying for feasibility, validity, and usability of development of competency standards in the field of records management. In this process, models for competency standard and elements based on competency units in the field of records management are suggested. This study will be ultimately expected to contribute to an adoption of manpower development system and a systematic method via procedures of approving expertise of records management being recently highlighted as an issue from revision process of records management act.

• Journal of the Korean Geotechnical Society
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• v.37 no.2
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• pp.5-17
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• 2021

The Moon has been an attractive planet as an outpost for deep space exploration since He-3 and water ice which can be used as energy resources were discovered. In-Situ Resource Utilization (ISRU) construction material fabrication method is required for sustainable space planet exploration. In this paper, the possibility of microwave sintering technology for construction material fabrication was evaluated using lunar regolith that can be easily collected from the Moon surface. Experimental assessment of the influence factors on microwave sintering was conducted using a hybrid sintering system for efficient processing. The heat distribution in the furnace was observed using thermal paper that is coated with a material formulated to change color when exposed to heat. Based on this result, sintered cylindrical KLS-1s with a diameter of 1 cm and a height of 2 cm were fabricated. Densities were measured for the sintered KLS-1s under rotating turntable conditions that have an effect of microwave dispersion. The more dielectrics were arranged, the more microwaves were dispersed reducing the heat concentration, and thus a uniformity of sintered KLS-1s was enhanced.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.49-60
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• 2020

The number of traffic control equipment installed to prevent traffic accidents increases every year due to continuous installation by the National Police Agency and local governments. However, it is installed based on qualitative judgment rather than engineering analysis results. The purpose of this study was to present additional installations in the future by presenting the installation criteria considering the severity of accidents for each road type and calculating the appropriate number of installations. ARI indicators that can indicate the severity of traffic accidents were developed, and road types were classified through analysis of variance and cluster analysis, and accident information by road type was analyzed to derive ARI of clusters with high traffic accident severity. The ARI values required to determine the installation of equipment for each road type were presented, and 5,244 additional installation points were analyzed.