• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.459-462
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• 2005

In finite element analysis of the PSC structures, the prestressing effect can be introduced by two ways, i.e, equivalent loads or initial stress. This study investigates the reason why the two schemes that adopt the different approaches produce the similar results. The discussion is applicable to the general finite elements that correspond to the concrete and tendons. Some of the detailed derivations of each scheme are presented. Numerical examples show the identical results for the two methods.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.459-461
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• 2013

선박에 승선하는 모든 선원들은 STCW 협약에서 요구하는 바와 같이 STCW 코드 A-I/6조에 따라 해당 훈련 및 평가에 대해 관리, 감독 및 감시되어야 하며, 선원들은 STCW 협약 요구 교육을 이수한 후 이에 대한 증서를 발급받아 해당 선박에 승선하고 있다. 그러나 이러한 법정교육에 대한 교육 이수증서양식이 국제적으로 통일되어 있지 않아 항만국통제(PSC) 검사시 검사관들이 해당 교육 이수 및 교육내용에 대한 식별이 어려우며, 또한 이수 증서 양식이 국가별로 제 각각이라 신뢰성이 검증되지 않은 증서도 발생하고 있는 실정이다. 이에 따라, STCW 협약 요구 법정교육을 분류 및 코드화하고, 이수증서에 대한 국제양식이 통일된다면, (1) 증성 양식의 통일화로 증서의 신뢰성을 높일 수 있을 것이며, (2) PSC 검사시 검사관의 혼돈을 방지하고, (3) 이수증서에 대해 거증서류로서의 활용도도 증대될 것이다. 따라서 이러한 문제를 해결하고, 선원 교육증서 양식 통일화에 대해 우리나라가 국제적으로 선도적인 역할을 할 수 있도록 이에 대한 연구를 수행하게 되었다.

• Current Photovoltaic Research
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• v.9 no.2
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• pp.23-30
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• 2021

Perovskite solar cells (PSCs) are currently attracting attention as a promising source of photovoltaic power generation for their rapid increase in efficiency within a short research period. However, the 2-step deposition method, which has been considered as a proper film fabrication route in commercialization point of view of PSC, requires a complicated control of environment to achieve high efficiency because each step of the process are affected by humidity in different manner. It is clearly a large hurdle for this technic to be transferred to industrialization. In this study, we developed a simple surface treatment by which high quality perovskite films can be fabricated through 2-step deposition method in a relatively wide humidity range without complicated humidity control at each step.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.103-112
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• 2007

The purpose of this study is to evaluate the characteristics of the structural behavior in precast segmental prestressed concrete girders, which consist of five precast segments. These girders were developed to save labor and cost in construction field reducing a term of work. Therefore, four different types of specimens of 25m in length were built, and they were tested and analyzed for observing flexural behavior. The analysis included the investigation of the flexural behaviors in varying tendon amount and at joints using the relationship between moment and deflection. Moreover, nonlinear finite element analysis was utilized to verify the experimental result.

• Journal of Life Science
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• v.30 no.4
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• pp.394-401
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• 2020

As embryonic stem cells become pluripotent, they may cause tumor development when injected into a host. Therefore, researchers are focusing heavily on the therapeutic potential of tissue-specific stem cells (adult stem cells) without resultant tumor formation. Adult stem cells can proliferate for a limited number of generations and are restricted to certain cell types (multipotent). Mature tissue cell types in mammals cannot be intrinsically dedifferentiated or transdifferentiated to adult stem cells. Hence, the technology of induced pluripotent stem cells (iPSCs) for reprogramming adult somatic cells was introduced in 2006, ushering in a new era in adult stem cell research. Although iPSCs have been widely used in the field, the approach has several limitations: instability of the reprogramming process, risk of incomplete reprogramming, and exposure to transgenes integrated into the cell genome. Two years before the introduction of the iPSC technique, the synthetic small molecule 2,6-disubstituted purine, called reversine, was introduced. Reversine can induce the dedifferentiation of committed cells into multipotent progenitor-type cells by reprogramming and converting adult cells to other cell types under appropriate stimuli. Thus, it can be used as a chemically induced multipotent cell agent to overcome the limitations of iPSCs. Also, as an alternative therapeutic approach for treating obesity, it can be used to generate beige cells by browning white adipocytes. While reversine has the potential to act as an anti-cancer agent, this review focuses on its role in differentiation, dedifferentiation, and transdifferentiation in somatic cells.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.2 s.29
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• pp.141-146
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• 2007

In this study, we have investigated several input factors and output factors to maintain safety management of domestic shipping companies, and then have analyzed the efficiency of performance about each shipping companies' safety management system from 1998 year to 2004 year using DEA method. The result of analysis shows that the annual mean efficiency index of total companies tended downward every year. Analysis was that the cause was increase of the cost of repairing ship, the cost of ship's stores and idle day of ship while the number of marine accidents and sanctions of PSC, ship's insurances and P&I insurances was decreased.

• Development and Reproduction
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• v.15 no.1
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• pp.41-52
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• 2011

In the present study, embryoid bodies (EBs) obtained from induced pluripotent stem cells (iPSCs) were induced to differentiate into germ lineage cells by treatment with bone morphogenetic protein 4 (BMP4) and retinoic acid (RA). The results were compared to the results for embryonic stem cells (ESCs) and multipotent spermatogonial stem cells (mSSCs) and quantified using immunocytochemical analysis of germ cell-specific markers (integrin-${\alpha}6$, GFR-${\alpha}1$, CD90/Thy1), fluorescence activating cell sorting (FACS), and real time-RT-PCR. We show that the highest levels of germ cell marker-expressing cells were obtained from groups treated with 10 ng/$m{\ell}$ BMP4 or 0.01 ${\mu}M$ RA. In the BMP4-treated group, GFR-${\alpha}1$ and CD90/Thy-1 were highly expressed in the EBs of iPSCs and ESCs compared to EBs of mSSCs. The expression of Nanog was much lower in iPSCs compared to ESCs and mSSCs. In the RA treated group, the level of GFR-${\alpha}1$ and CD90/Thy-1 expression in the EBs of mSSCs Induced pluripotent stem cells, Mouse embryonic stem cells, Multipotent spermatogonial stem cells, Germ cell lineage, Differentiation potential. was much higher than the levels found in the EBs of iPSCs and similar to the levels found in the EBs of ESCs. FACS analysis using integrin-${\alpha}6$, GFR-${\alpha}1$, CD90/Thy1 and immunocytochemistry using GFR-${\alpha}1$ antibody showed similar gene expression results. Therefore our results show that iPSC has the potential to differentiate into germ cells and suggest that a protocol optimizing germ cell induction from iPSC should be developed because of their potential usefulness in clinical applications requiring patient-specific cells.

• ETRI Journal
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• v.15 no.3
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• pp.1-26
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• 1994

Simulated annealing is an attractive, but expensive, heuristic method for approximating the solution to combinatorial optimization problems. Attempts to parallel simulated annealing, particularly on distributed memory multicomputers, are hampered by the algorithm's requirement of a globally consistent system state. In a multicomputer, maintaining the global state S involves explicit message traffic and is a critical performance bottleneck. To mitigate this bottleneck, it becomes necessary to amortize the overhead of these state updates over as many parallel state changes as possible. By using this technique, errors in the actual cost C(S) of a particular state S will be introduced into the annealing process. This paper places analytically derived bounds on this error in order to assure convergence to the correct optimal result. The resulting parallel simulated annealing algorithm dynamically changes the frequency of global updates as a function of the annealing control parameter, i.e. temperature. Implementation results on an Intel iPSC/2 are reported.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.4_1
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• pp.759-769
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• 2024

The Kano model, a two-dimensional quality theory, is widely used as a useful tool for measuring potential customer requirements by utilizing the concept of the Potential Customer Satisfaction Coefficient (PCSC). There is growing evidence that the PCSC, comprising the Potential Satisfaction Coefficient (PSC) and Potential Dissatisfaction Coefficient (PDC) and utilizing Kano's four quality dimensions (A, O, M, and I), can be particularly useful in determining the relative importance of quality characteristics in IPA. Despite prior studies utilizing the PCSC concept for characterizing importance, attempts to determine the relative significance among quality dimensions have been relatively scarce. This study aims to use PCSC and IPA to demonstrate which quality dimension is more significant than the others. The author analysed 32 Kano related articles, encompassing 34 cases, using IPA. The results indicate that the proposed equations are valid for assessing characteristic importance, with O or M is perceived as more important than A or I.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.235-249
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• 2011

A new form of I-type PSC bridge girder, which has hole in the web, is proposed in this paper. Three different concepts were combined and implemented in the design. First of all, a girder was precast at a manufacturing plant as divided pieces and assembled at the construction site using post-tensioning method, and the construction period at the site will be reduced dramatically. In this way, the quality of concrete can be assured at the manufacturing factory and concrete curing can be well controlled, and the spliced girder segments can be moved to the construction site without a transportation problem. Secondly, a numerous number of holes was made in the web of the girder. This reduces the self-weight of the girder. But more important thing related to the holes is that about half of the total anchorages can be moved from the girder ends into individual holes. The magnitude of negative moment developed at girder ends will be reduced. Also, since the longitudinal compressive stresses are reduced at ends, thick end diaphragm is not necessary. Thirdly, Prestressing force was introduced into the member through multiple stages. This concept of multi-stage prestressing method overcomes the prestressing force limit restrained by the allowable stresses at each loading stage, and maximizes the magnitude of applicable prestressing force. It makes the girder longer and shallower. Two 50 meter long full scale girders were fabricated and tested. One of them was non-spliced, or monolithic girder, made as one piece from the beginning, and the other one was assembled using post-tensioning method from five pieces of segments. It was found from the result that monolithic and spliced girder show similar load-deflection relationships and crack patterns. Girders satisfied specific girder design specification in flexural strength, deflection, and live load deflection control limit. Both spliced and monolithic holed web post-tensioned girders can be used to achieve span lengths of more than 50m with the girder height of 2 m.