• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.275-282
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• 2009

Generally, the sinusoidal cavity dither is adopted to ring laser gyroscope for eliminating the lock-in which is non-linear effect at the small rotation input. Despite this method, there are some remained errors which are generated at the dither turnaround, and those errors produce random walk which is a general character of a ring laser gyroscope. As one of the numerous research results for compensating these errors, there is a special lock-in compensation method which is the method of error estimation and compensation by comparing the beat signal periods of before and after the dither turnarounds. In this paper, by ring laser gyroscope modeling and numerical analysis, we verified the theoretical validity and confirmed the effectiveness of this method in expectation of the possible beat signal measurement time resolution. As a result, we confirmed the random walk decreases from a-half to a-third by this lock-in compensation method. So, it is expected to be a remarkable method for reducing the INS alignment time.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.38-45
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• 2002

Hydrates are solid cryctallines resembling ice in appearance, which are consist of a gas molecule surrounded by a cage of water molecules. Because of containning a large amount of methane, hydrates have been considered as a future energy resource. However, the formation of hydrates in the oil and gas industries has been known as a serious problem for a long time. The formation of hydrate in pipeline is common in seasonally cold or sub-sea environments with low temperatures and high pressures. Especially, hydrate plug formation becomes a real menace to flow assurance in inadequately protected transmission lines. This study was carried out for the purpose of understanding mechanism of hydrate plugging and examining formation conditions of hydrate in high pressure gas pipeline. In this study, we measured hydrate equilibrium conditions under the various flowing conditions with the methane. The results were presented both the plugging tendency and the effect of flowing velocity.

• Journal of Intelligence and Information Systems
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• v.13 no.2
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• pp.27-41
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• 2007

Nowadays the context-aware systems have been regarded as a promising opportunity to create differentiated e-marketplaces. Context-aware system aims to provide personalized services by understanding the user's current situation which is automatically acquired from the context data. This aim naturally leads us to a motivation to evaluate to what extent a system is context-aware. Even though lots of endeavors have stated about the level of context-aware system, a structured evaluation has been so far very rare. Hence, the purpose of this paper is to propose a two-phased methodology for assessing context-aware systems. In the first phase, we perform a requisite analysis to discriminate a context-aware system from general or context-based systems. Once an information system is recognized as context-aware system, then level of collaboration, mobility and embeddedness is derived to determine the level of context-aware system in the second phase. To do so, device collaboration diagram (DCD) is proposed to visualize the system architecture. Moreover, readiness and level of system are Jointly considered in the phase to provide a development strategy for each context-aware system development project. To show the feasibility of the idea proposed in this paper, legacy context-aware systems are actually analyzed and evaluated.

• Journal of Teachers' Pension
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• v.4
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• pp.175-205
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• 2019

본 연구의 목적은 폐교로 인해 퇴직한 사립학교 교직원을 대상으로 사학연금의 재해보상기금을 활용하여 실업급여를 제공하는 방안을 모색하는데 있다. 이를 위해 먼저 폐교 퇴직 교직원 현황 및 사학연금에서 폐교로 인한 퇴직 시 연금 지급규정, 재해보상 관련 쟁점, 고용보험 임의가입방안 관련 쟁점 등에 대해 고찰하였다. 다음으로 폐교로 인한 퇴직 교직원에 대한 정책방안들로 현행안, 재해보상기금을 활용한 구직급여 제공방안, 고용보험 임의가입안에 대한 재정추계를 실시하였다. 주요 분석결과는 다음과 같다. 첫째, 불과 5년 뒤인 2024학년도부터는 대입가능자원이 대학입학정원을 크게 밑돌 것으로 전망되고 이로 인해 대학의 통·폐합과 구조조정 등이 발생하여 현재보다 훨씬 더 많은 대학이 폐교될 것으로 예상된다. 둘째, 현행 사학연금법 상연금지급개시연령은 65세이나, 공무원연금법을 준용하고 있는 사학연금에서 폐교로 인해 퇴직하는 경우 퇴직 때부터 5년이 경과한 때 연금을 지급하는 규정으로 인해 여러 문제점들이 발생하고 있다. 셋째, 폐교로 인한 비자발적 퇴직 교직원의 소득활동 중단에 따른 소득 대체 및 생활안정을 위한 방안마련이 시급하다. 넷째, 산재보험과 공무원연금·군인연금 등 공적 재해보상제도들은 모두 업무상 또는 공무상 사고나 질병으로 부상·질병·장해·사망이 발생하면 재해로 정의하고 있어 사학연금에서 폐교를 재해로 포함시키는 것은 적합하지 않으며, 실업에 대응하는 사회보장제도인 고용보험에 포함시키는 것이 보다 타당할 것으로 보인다. 다섯째, 사립학교 교직원에 대한 고용보험적용 여부를 논의하기 위해서는 대학교수의 법적 지위와 근로기준법의 적용가능성이 중요한데, 향후 대법원이 대학교수를 근로기준법상 근로자로 판단한다면 사학 교직원의 고용보험 가입도 가능하게 될 것이다. 여섯째, 사학연금가입자들을 위한 고용보험 도입이 바람직하나, 이것이 단기간 내에 실행되기 어렵다면 고려 가능한 대안으로 공무원연금과는 다른 사학 교직원 직무에서 발생하는 재해의 특성을 고려하여 사학재해보상제도에서 폐교로 인한 퇴직을 재해보상에 포함시키고 구직급여를 제공하는 방안을 검토해 볼 수 있다. 또한 재정추계결과는 다음과 같다. 첫째, 현재 폐교로 인한 퇴직 시 제공되는 연금 대신에 재해보상기금으로 구직급여를 제공할 경우 사학연금기금에 재정적으로 상당히 긍정적 효과가 있을 것으로 예상된다. 둘째, 폐교로 인한 2018년 현재 연금수급자(285명)의 예상 연금급여액 추계에 의하면 2050년까지 누적해서 볼 경우, 재해보상기금을 활용하여 구직급여를 제공하는 방안이 폐교로 인한 퇴직 시 연금을 지급하는 현행안보다 2018년 현재가치로 123억 원 정도 유리한 것으로 나타났다. 셋째, 현재 수급자와 미래 수급자의 예상 연금급여액 추계에 의하면 2028년까지 누적해서 볼 경우, 재해보상기금을 활용하여 구직급여를 제공하는 방안이 현행안보다 2018년 현재가치로 747억 원 정도 재정적으로 유리한 것으로 나타났다.

• Korean Journal of Ichthyology
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• v.33 no.2
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• pp.107-116
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• 2021

Two stone loaches (Nemacheilidae, Cypriniformes), Barbatula toni (Dybowski, 1869) and B. nuda (Bleeker, 1864), have been recognized in the Korean waters to date. Recently, due to indiscriminate artificial introduction as well as the change of their habitats induced by natural disasters, it seems to be concerned about the damage of species-specific geographic boundaries. We examined the genetic difference of two Korean Barbatula species by the haplotype network based on the Cytochrome b sequences of mitochondrial DNA and the phylogenetic relationships among them including Barbatula fishes occurring around the Korean peninsula. As a result, three and 29 haplotypes were obtained from B. toni and B. nuda, respectively, and totally three clades comprising "toni group", "nuda hangang group", and "nuda donghae group" were identified. The sequence variable sites among them was 10~24%, showing a difference of interspecific level. Phylogenetic relationships of the latter group, especially, forms an independent cluster discriminating with other two groups as well as the Chinese, Japanese, Russian, and European Barbatula species, suggesting the possibility of the specific level divergence.

• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1261-1271
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• 2018

This study evaluates the applicability of the classification rule of hydrological soil group proposed by Lee et al. (2018) with its application to three river basins (Jungmuncheon, Cheonmicheon, and Hancheon) in Jeju Island. The CN values are estimated as results of this application to these three basins, which is then compared with those estimated by applying the conventional three methods. Additionally, previous studies related with the classification of soil groups of Jesu Island, such as the infiltration and rainfall-runoff analysis, are reviewed to evaluate how the resulting hydrological soil groups vary depending on the adopted classification method.. Summarizing the results is as follows. (1) Comparison result of the hydrological soil groups of Jeju Island with respect to the classification method shows that the soil group B is dominant in the application of Lee et al. (2018). However, it is hydrological soil groups C and D in the application of Hu and Jung (1987), hydrological soil groups A and C in the application of Jung et al. (1995), and hydrological soil group D in the application of RDA (2007). (2) In all the applications of Lee et al. (2018) to three selected river basins in Jeju Island, the CN valuse are found to be smaller than those by other conventional three methods.. Lastly, (3) The evaluation results of previous studies related with the classification of hydrological soil groups analysis in Jeju Island shows that the CN value in the Jeju Island may be smaller than those estimated by conventional three methods, also the initial loss higher than 0.2S.

• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1273-1284
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• 2018

The flow and bed change were analyzed using the CCHE2D model, which is a two-dimensional numerical model, at a confluence of the Namhan River and Seom River where deposition occurs predominantly after the "Four Major Rivers Restoration Project." The characteristic of the junction is that the tributary of Seom River joined into the curved channel of the main reach of the Namhan River. The CCHE2D model analyzes the non-equilibrium sediment transport, and the adaptation lengths for the bed load and suspended load are important variables in the model. At the target area, the adaptation length for the bed load showed the greatest influence on the river bed change. Numerical simulation results demonstrated that the discharge ratio ($Q_r$) change affected the flow and bed change in the Namhan River and Seom river junction. When $Q_r{\leq}2.5$, the flow velocity of the main reach increased before confluence, thereby reducing the flow separation zone and decreasing the deposition inside the junction. When $Q_r$>2.5, there was a high possibility that deposition would be increased, thereby forming sand bar. Numerical simulation showed that a fixed sand bar has been formed at the junction due to the change of discharge ratio, which occurred in 2013.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.7-13
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• 2019

This study aims to develop a FE Model to simulate dissimilar friction stir welding and to address its potential for fundamental analysis and practical applications. The FE model is based on Coupled Eulerian-Lagrangian approach. Multiphysics systems are calculated using explicit time integration algorithm, and heat generations by friction and inelastic heat conversion as well as heat transfer through the bottom surface are included. Using the developed model, friction stir welding between an Al6061T6 plate and an AZ61 plate were simulated. Three simulations are carried out varying the welding parameters. The model is capable of predicting the temperature and plastic strain fields and the distribution of void. The simulation results showed that temperature was generally greater in Mg plates and that, as a rotation speed increase, not the maximum temperature of Mg plate increased, but did the temperature of Al plate. In addition, the model could predict flash defects, however, the prediction of void near the welding tool was not satisfactory. Since the model includes the complex physics closely occurring during FSW, the model possibly analyze a lot of phenomena hard to discovered by experiments. However, practical applications may be limited due to huge simulation time.

• 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.

• Korean Journal of Psychosomatic Medicine
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• v.28 no.2
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• pp.135-142
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• 2020

Objectives : To identify the relationship between somatization, stress, depression, anxiety, and psychological symptoms risk for nurses working in the intensive care unit. Create clinical evidence of psychosomatic medicine research and complement the meaning of somatization. Methods : Seventy of the mental health checkups conducted by the National Mental Health Center among the nurses using tools including Perceived Stress scale, Fatigue Severity Scale, Patient Health questionnaire-15, Korean Beck Depression Inventory, Korean Beck Anxiety Inventory, and Symptom Checklist-90-Revision. Results : 12.9% of the patients experienced more than moderate somatization. There was no statistical relationship between somatization and psychological stress perception, but feeling of anxiety and decreased self-confidence were related to the level of somatization. The group with severe somatization experienced more depression and anxiety. The group with high physical fatigue also had no statistical relationship with psychological stress perception, but had an effect on the feeling of tension, stress, or decreased control. Physical fatigue level was increased by experience of depression, not by anxiety. For psychological symptoms the higher the level of somatization, the higher the obsession and hostility was explored. In the linear regression model, stress, depression, and anxiety accounted for 39.3% of somatization and 16.1% of physical fatigue symptoms. Conclusions : We can estimate the decrease in stress cognitive symptoms, accompanying depression and anxiety, compulsion and hostility as characteristics of somatization. The causal relationship between somatization and psychological symptoms cannot be confirmed in this study, but the interrelationships are observed, can be referred to mediation strategies.