• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.7-15
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• 2023

The electric submersible pump (ESP) has been operating in production wells around the world because of its high applicability and operational efficiency among artificial lift techniques. When operating an ESP in a reservoir, variables such as temperature, pressure, gas/oil ratio, and flow rate are factors that affect ESP performance. In particular, free gas in the production fluid is a major factor that reduces the life and operational efficiency of ESP. This study presents the flow loop system which can implement the performance and damage tests of ESP considering field operating conditions to quantitatively analyze the variables that affect ESP performance. The developed apparatus in an integrated system that can diagnose the failure and causes of ESP, and detect leak of tubing by linking ESP and tubing as one system. In this study, the flow conditions for stable operation of ESP were identified through single phase and two phase flow experiments related to evaluation for the performance of ESP. The results provide the basic data to develop the failure prediction and diagnosis program of ESP, and are expected to be used for real-time monitoring for optimal operating conditions and failure diagnosis for ESP operation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.638-643
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• 2004

소형화된 기계가공시스템은 사용재료의 다양화와 에너지 및 공간의 감소와 같은 장점을 가지고 작고 정밀한 부품을 가공할 수 있는 시스템으로 주목받고 있다. 이러한 시스템이 비록 그 크기가 일반적인 가공시스템에 비해 작지만 정렬 및 조립공정, 기계요소의 불완정성에 의한 기하학적 오차는 여전히 존재한다. 기하학적 오차 평가는 기계시스템의 정밀도를 효과적으로 적은 비용으로 향상시킬 수 있는 오차보정기술을 적용할 수 있는 토대가 된다. 일반적으로, 3 축의 직선축으로 이루어진 공작기계는 21 개의 오차요소를 가진다. 레이져간섭계는 이러한 오차요소를 평가하는데 널리 사용되고 있지만 광학계를 정렬하고 설치하는 데 많은 어려움이 있으며 한번의 설치로 한 개의 오차요소만이 측정 가능하다. 또한, 소형공작기계의 경우, 그 크기로 인해 기존의 레이져 간섭계를 직접적으로 적용할 수 없다. 따라서, 본 연구에서는 소형공작기계를 포함한 소형가공시스템의 기하학적 오차 평가를 위한 새로운 다자유도 측정시스템을 제안하였다. 5 개의 정전용량변위센서를 사용하는 이 시스템을 통해 한 축의 움직임에 따른 5 개의 오차요소를 동시에 측정 가능하다. 균질 변환행렬을 이용한 측정알고리듬을 구성하고 이를 모의시험을 통해 평가하였다. 수학적 모델링을 통해 각 센서의 출력값을 유도하고 이를 이용하여 각 오차요소를 계산하기 위한 식을 유도하였다. 여기서, 단순화된 식을 적용한 경우, 임의의 오차에 대한 측정 알고리듬의 정확도를 평가하였다. 또한, 측정 시스템의 설치시 발생하는 셋업오차에 대한 측정 알고리듬의 민감도 분석을 행하였다. 제안하는 측정 시스템은 구조가 간단하고 고가의 부가장비가 필요치 않다. 또한, 적은 비용으로 구성할 수 있으며 높은 측정 정밀도를 가지고 소형가공시스템에 필요한 오차 평가를 행할 수 있다.가 함유된 계란을 생산하고 섭취하였을 때 특정항체들의 결합을 통해 병원성 미생물의 성장이나 군체를 형성하는 것을 무력화시켜 결과적으로 병원균을 감소시키거나 억제시킨다는 점이다. 오늘날 약물에 내성을 지닌 박테리아의 출현으로 질병감염을 막는데 항생제의 사용효과가 점차 감소하고 있기 때문에 이러한 항생제를 대체할 수 있는 방안으로 계란항체를 이용할 수 있다.한 중공 플랜지 형상의 단조 방법 중 보다 적절한 단조방법인 압조 단조에 있어서 일반적으로 사용되고 있는 SM10C에 대한 유한요소 해석을 수행하였으며, 제품의 형상비에 따라 폴딩 결함의 발생 유무를 검토하고, 폴딩 결함 없이 단조하기 위한 중공 플랜지의 형상한계 비를 제시하였다.도 경미하게 나타났으나, 경련이 나타난 쥐에서는 KA만을 투여한 흰쥐와 구별되지 않았다. 이상의 APT의 항산화 효과는 KA로 인한 뇌세포 변성 개선에 중요한 인자로 작용할 것으로 사료되나, 보다 명확한 APT의 기전을 검색하고 직접 임상에 응응하기 위하여는 보다 다양한 실험 조건이 보완되어야 찰 것으로 생각된다. 항우울약들의 항혈소판작용은 PKC-기질인 41-43 kD와 20 kD의 인산화를 억제함에 기인되는 것으로 사료된다.다. 것으로 사료된다.다.바와 같이 MCl에서 작은 Dv 값을 갖는데, 이것은 CdCl$_{4}$$^{2-}$ 착이온을 형성하거나 ZnCl$_{4}$$^{2-}$ , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경

• Journal of Service Research and Studies
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• v.11 no.1
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• pp.59-79
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• 2021

Service-related research in accordance with the transition to the service economy era has been conducted in a wide variety of ways, but the development of a service-related scale suitable for the present time is still insignificant. The purpose of this study is to define the nature of services and to develop measurement items for them. First, four categories of service nature were adopted in the previous study. The four categories are 'relationship', 'interactivity', 'horizontality', and 'harmony'. In this study, sub-factors and specific items of each of these four service essences were extracted and developed as measurable items. As a qualitative study, the four categories of sub-factors were extracted, and a mixed study was adopted to prove the reliability and validity of the extracted factors through quantitative studies. The scale items were identified through literature study, free response method, and Delphi technique, and the measurement items were refined through a second questionnaire of 30 Delphi panels composed of experts. As a result of the study, 15 out of 52 questions for relationship, 11 out of 45 questions for bilateral direction, 9 out of 33 questions for horizontality, and 17 out of 61 questions for harmonization were derived after secondary refining. Through this study, it was possible to uncover new essential items suitable for the service economy era. SNS, network, synergy, platform, system, real name, and breakthrough are concepts that have not been obtained in previous studies, and can be seen as contributions of this study. However, due to various limitations, this study did not cover all aspects of the service, but mainly dealt with people-centered services, which are part of the service. In the future, it is necessary to study the development of service essence measurement items for the overall aspect of services developed according to the evolution of the service economy era.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.381-388
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• 2023

This thesis is purposed to develop a regional-customized education program selection model using big data analysis. Based on the literature review, the concepts and characteristics of big data and lifelong education are analyzed. In addition, this thesis presents how to collect the data for lifelong education and to use big data suitable for the characteristics of lifelong education. Based on these results, a regional- customized lifelong education program selection model is developed. The regional customized lifelong education program model is developed by the following six steps. The customized education program model proposed in this study has a high degree of flexibility in terms of practical use, as it can be utilized in real-time data provision methods such as the nationally approved Lifelong Learning Personal Status Survey without the need for analysis one year later, allowing for selective analysis and future predictions. It is clear that there is a significant need and value for big data in the education field. Furthermore, all programs used in the sample model are provided free of charge, and due to the programming nature, the community is actively engaged in exchanges, making it very easy to modify and improve for the development of a more complete education program model in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.559-573
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• 2008

In this study, we newly proposed 3-D nonlinear wave driver utilizing the Navier-Stokes Eq. the numerical integration of which is carried out using SPH (Smoothed Particle Hydrodynamics), an internal wave generation with the source function of Gaussian distribution and an energy absorbing layer. For the verification of new 3-D nonlinear wave driver, we numerically simulate the sloshing problem within a parabolic water basin triggered by a Gaussian hump and uniformly inclined water surface by Thacker (1981). It turns out that the qualitative behavior of sloshing caused by relaxing the external force which makes a free surface convex or uniformly inclined is successfully simulated even though phase error is visible and an inundation height shrinks as numerical simulation more proceeds. For the more severe test, we also simulate the nonlinear shoaling and refraction over uniform beach of wedge shape. It is shown that numerically simulated waves are less refracted than the linear counterpart by Hamiltonian ray theory due to nonlinearity, energy dissipation at the bottom and side walls, energy loss induced by breaking, and the hydraulic jump occurring when breaking waves encounter a down-rush by the preceding wave.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1D
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• pp.17-25
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• 2010

In Korea, the importance of walking has not been stood out in relief because of the rapid increase of a car on a drastic economic growth in the past half a century. Walking has failed to be recognized as a traffic measure or one of basic human rights. Therefore this study brings up problems of weakened walking right from increase of cars and examines reinforcing policies for walking right of advanced countries. And this study presents institutional devices for introducing walking safety measures of advanced countries reflecting pedestrian satisfaction and opinions about walking right. The results of this study are, First, pedestrians' walking liberty is guaranteed, Second, how to repair walking environment is searched and practical measures are analyzed to find out what is applicable to Korea, can reduce pedestrian accidents and is wanted by pedestrians using GAP analysis and Structural Equation. Third, basic data for upcoming selection of policies are presented by analyzing pedestrian satisfaction assuming that selected measures are operated.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.380-388
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• 2023

This study estimates the metacentric height (GM) of a model ship by varying the transverse weight distribution, considering the effects of the roll period and moment of inertia, and compares it with the GM values measured by the inclining test. In the process, the relationship between the values is analyzed. Three types of ships-a 7-ton fishing vessel, 20-ton fishing vessel, and KRISO Very Large Crude-oil Carrier (KVLCC)-were used for the experiment and comparison. The roll period and moment of inertia were measured using the free roll decay and swing frame tests, and the GM was measured using inclining test. The estimated GM from the roll period and moment of inertia showed the same trend as the GM measured using the inclining test in the change of the weight distribution. However, the GM values measured using the inclining test were lower. Therefore, additional correction factors or parameters other than the roll period and moment of inertia are necessary for estimating GM. In the future, the relationship between the weight center and the estimated GM will be analyzed to derive the correction factors.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.133-139
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• 2024

The purpose of this study was to investigate the effects of robot play linked to environmental picture books on the Environmentally Friendly attitudes of 5-year-old children. For this purpose, 24 5-year-old children from Seoul Y Kindergarten and 20 5-year-old children from E Kindergarten were selected as comparison subjects. In order to examine the differences between the groups, the experimental group performed 'Robot Play Linked to Environmental Picture Books' and the comparative group performed 'Free Play After Appreciating Environmental Picture Books'. The collected data were analyzed through independent sample t-test, which compares the average between the two groups using SPSS 29.0 statistical program. As a result of the study, there was a significant difference in all sub-areas of children's environment-friendly attitude(nature-friendly attitude, environmental preservation attitude), and these findings are meaningful as a basis for the direction of new environmental education of play-centered early childhood environmental education based on the value of new play media support called robot.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.1-10
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• 2024

In a previous study, a structure of a superplastic yoke consisting of a thin FR4 layer laminated with viscoelastic tape on both sides of a shape memory alloy (SMA) was proposed to reduce residual vibration generated by a deployable solar panel during high motion of a satellite. Damping properties of viscoelastic tapes will change with temperature, which can directly affect vibration reduction performance of the yoke. To check damping performance of the yoke at different temperatures, free damping tests were performed under various temperature conditions to identify the temperature range where the damping performance was maximized. Based on above temperature test results, this paper predicts temperature of the yoke through orbital thermal analysis so that the yoke can have effective damping performance even if it is exposed to an orbital thermal environment. In addition, the thermal design method was described so that the yoke could have optimal vibration reduction performance.