• International Journal of Naval Architecture and Ocean Engineering
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• 제10권2호
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• pp.129-140
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• 2018

A residual stress generated in the steel structure is broadly categorized into initial residual stress during manufacturing steel material, welding residual stress caused by welding, and heat treatment residual stress by heat treatment. Initial residual stresses induced during the manufacturing process is combined with welding residual stress or heat treatment residual stress, and remained as a final residual stress. Because such final residual stress affects the safety and strength of the structure, it is of utmost importance to measure or predict the magnitude of residual stress, and to apply this point on the design of the structure. In this study, the initial residual stress of steel structures having thicknesses of 25 mm and 70 mm during manufacturing was measured in order to investigate initial residual stress (hereinafter, referred to as initial stress). In addition, thermal elastic plastic FEM analysis was performed with this initial condition, and the effect of initial stress on the welding residual stress was investigated. Further, the reliability of the FE analysis result, considering the initial stress and welding residual stress for the steel structures having two thicknesses, was validated by comparing it with the measured results. In the vicinity of the weld joint, the initial stress is released and finally controlled by the weld residual stress. On the other hand, the farther away from the weld joint, the greater the influence of the initial stress. The range in which the initial stress affects the weld residual stress was not changed by the initial stress. However, in the region where the initial stress occurs in the compressive stress, the magnitude of the weld residual compressive stress varies with the compression or tension of the initial stress. The effect of initial stress on the maximum compression residual stress was far larger when initial stress was considered in case of a thickness of 25 mm with a value of 180 MPa, while in case of thickness at 70 mm, it was 200 MPa. The increase in compressive residual stress is almost the same as the initial stress. However, if initial stress was tensile, there was no significant change in the maximum compression residual stress.

• 기록학연구
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• 제11호
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• pp.15-40
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• 2005

'Governance' is a subject that is widely discussed these days in the government and the academic world. I think that the new concept, 'governance', is a strategy to develop the democracy of the society in its institutional and functional aspects. When we are going to discuss about governance, public records and their relationships, without understanding the meaning of 'public' in Korea, we cannot expect to discuss the matter precisely. It is said that Korean public service sectors are awash with authoritarianism and unreasonableness, and that they are at the center of seething corruption and bribe scandals. It is the legacy that the regimes adopted in the aftermath of the Japanese colonial rule for 35 years. The colonial legacy included not simply the practice of the Japanese colony, but also people who had collaborated the Japanese. The American military government and Rhee, Sung-Man regime also appointed the same officials to government posts. As was the same case in other areas including economy, press, education, politics, law, etc. In this point of view, "Righting historical wrongs", a controversial issue now in Korea, aims at establishing the right relationships between an individual and the public, and eventually laying the foundation of democracy for future generation, a procedure of achieving good governance. Apparently, Korea has made progress in developing democracy, as well as in reforming the government policy and organization. Many independent commissions are performing the projects instead of the government institutions that mandated to do the job, but has not played their roles. The e-government projects in Korea was launched in 2001 by the former administration. However, the confusion of records-management after the promulgation of the act is the result of the lack of strategy and the inconsistency of the vision. Good record-keeping supports effective, transparent and accountable government. Accountability is a key element of good governance. It is a recognized fact that without information, there is no guidance for decision-making, and accountability. Thus without records, there is no accountability for the decisions of actions. Transparency means that the decisions taken and their enforcement are carried out based on led-out rules and regulations. When both accountability and transparency are non-existent, good governance is bound to fail. Archival institutions have to give an attention to inner-governance because of the new trend of archival practice, namely 'macro-appraisal'. This 'macro-appraisal' is a kind of a functions-based approach. However, macro-appraisal focuses not just on function, but on the three-way interaction of function, structure and citizen, which combined reflect the functioning of the state within civil society, that is to say, its governance. In conclusion, the public and democracy are major challenges in the Korean society. The so-called good governance requires good record management. In this respect, records managers are in the front line of instituting good governance, and achieving better public and democracy for future generation, a procedure of achieving good governance.

• Design & Manufacturing
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• 제13권2호
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• pp.30-36
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• 2019

Traditional cell culture(2-dimensional) is the method that provide a nutrient and environment on a flat surface to cultivate cells into a single layer. Since the cell characteristics of 2D culture method is different from the characteristics of the cells cultured in the body, attempts to cultivate the cells in an environment similar to the body environment are actively proceeding in the industry, academy, and research institutes. In this study, we will develop a technology to fabricate micro-structures capable of culturing cells on surfaces with various curvatures, surface shapes, and characteristics. In order to fabricate the hemispheric plastic structure(thickness $50{\mu}m$), plastic preform mold (hereinafter as "preform mold") corresponding to the hemisphere was first prepared by injection molding in order to fabricate a two - layer structure to be combined with a flat plastic film. Then, thermoplastic polymer dissolved in an organic solvent was solidified on a preform mold. As a preliminary study, we proposed injection molding conditions that can minimize X/Y/Z axis deflection value. The effects of the following conditions on the preform mold were analyzed through injection molding CAE, [(1) coolant inlet temperature, (2) injection time, (3) packing pressure, (4) volume-pressure (V/P). As a result, the injection molding process conditions (cooling water inlet temperature, injection time, holding pressure condition (V / P conversion point and holding pressure size)) which can minimize the deformation amount of the preform mold were derived through CAE without applying the experimental design method. Also, the derived injection molding process conditions were applied during actual injection molding and the degree of deformation of the formed preform mold was compared with the analysis results. It is expected that plastic film having various shapes in addition to hemispherical shape using the preform mold produced through this study will be useful for the molding preform molding technology and cast molding technology.

• 한국재료학회지
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• 제29권11호
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• pp.720-726
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• 2019

Recently, research on cost reduction and efficiency improvement of crystalline silicon(c-Si) photovoltaic(PV) module has been conducted. In order to reduce costs, the thickness of solar cell wafers is becoming thinner. If the thickness of the wafer is reduced, cracking of wafer may occur in high temperature processes during the c-Si PV module manufacturing process. To solve this problem, a low temperature process has been proposed. Conductive paste(CP) is used for low temperature processing; it contains Sn57.6Bi0.4Ag component and can be electrically combined with solar cells and ribbons at a melting point of $150^{\circ}C$. Use of CP in the PV module manufacturing process can minimize cracks of solar cells. When CP is applied to solar cells, the output varies with the amount of CP, and so the optimum amount of CP must be found. In this paper, in order to find the optimal CP application amount, we manufactured several c-Si PV modules with different CP amounts. The amount control of CP is fixed at air pressure (500 kPa) and nozzle diameter 22G(outer diameter 0.72Ø, inner 0.42Ø) of dispenser; only speed is controlled. The c-Si PV module output is measured to analyze the difference according to the amount of CP and analyzed by optical microscope and Alpha-step. As the result, the optimum amount of CP is 0.452 ~ 0.544 g on solar cells.

• 한국철학논집
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• 제36호
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• pp.259-291
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• 2013

이 글은 배위의 "숭유론"을 문제의식과 철학사상 두 부분으로 나누어, 그것이 갖는 목적과 의미를 고찰한다. "숭유론"의 문제의식은 다음 세 가지이다. 첫째, 노자의 중심사상을 '허무'로 규정하는 것은 오해이다. 둘째, 과거의 사상가들이 '허무론'을 제대로 비판하지 못하여 그것의 확산을 억제하지 못했다. 셋째, 귀무론의 유행은 생활풍속의 문란과 사회질서의 붕괴를 초래한다. 이러한 문제의식에 기초하여 배위는 '유'를 천지만물의 존재와 운동의 근거로 하는 다음과 같은 철학사상을 건립한다. 첫째, '도'는 '만유'의 종합일 뿐이고, '만유' 밖에 있는 추상적 실체가 아니다. 둘째, '무'는 '유'가 없어진 상태일 뿐이고, '유'는 오로지 '유'로부터 말미암아 이루어진다. 셋째, '유'는 독립적 실체가 아니기 때문에 외재의 '유'에 의존해 생존한다. 그러므로 외재의 '유'를 파악하는 것이 존망의 관건이다. 넷째, '만유'는 상호 의존하는 관계에 있기 때문에 '만유'는 함께 있어도 서로 해하지 않는다. 인류도 상호의존적 관계를 맺어야만 살아갈 수 있는 존재이다. 그러므로 존재론적으로 사회제도와 윤리는 인간세계에 반드시 필요하다. 이처럼 배위는 '만유'의 '상호의존'이라는 존재론적 특성을 기초로 '도덕질서'의 정당성을 확보하여 무너진 생활풍속과 사회질서를 다시 세우려한다.

• 한국빅데이터학회지
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• 제5권2호
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• pp.201-213
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• 2020

위험에 대한 인간의 반응은 인지적 요인뿐만 아니라 정서적 요인에도 유의미한 영향을 받는다는 경험적 연구에도 불구하고, 정보 프라이버시 연구에서는 감정적 요인의 역할이 제대로 규명되지 않고 있다. 본 연구는 정서적 관점에서 위치기반 서비스(Location-based service) 사용자의 프라이버시 위험에 대한 대응행위를 탐색하고자 한다. 구체적으로, 본 연구는 세 가지 유형의 개인정보 위협(수집, 해킹, 2차 사용), 두 가지 감정적 반응(걱정, 분노) 및 대응행위(지속적인 사용의도)의 관계를 탐색하였다. 이를 위해 위치기반서비스(Location-based service) 사용자 552 명에 대해 설문조사를 실시하였다. 특정 개인정보 위협에 대한 인식과 특정 감정적 반응의 결합이 지속적 사용의도에 미치는 영향을 분석하기 위해 데이터마이닝 기법 중 하나인 연관규칙(association rule)을 활용하여 분석을 진행하였다. 그 결과 위험에 대한 인식과 정서적 반응의 결합에 따라 사용의도에 차이가 나타났으며, 대체로 개인정보의 2차 사용에 대해 분노의 감정이 유발될 경우 사용의도가 가장 크게 감소하는 것으로 나타났다. 본 연구는 정보 프라이버시 사용자 연구에 감정적 요인을 포함함으로써, 기존의 인지적 접근방식 편향을 보완하고 프라이버시 대응행위에 대한 포괄적 이해를 제공한다는 점에서 학문적 의의가 있다.

• 박물관보존과학
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• 제26권
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• pp.119-142
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• 2021

금동은제식리는 무령왕릉에서 출토된 무령왕의 식리로 결실된 부분이 많아 재조사의 필요성이 꾸준히 제기되었다. 이에 과학적인 보존처리 및 분석을 진행하여 제작기법을 연구하였다. 보존처리는 형태 복원 및 편 접합에 중점을 두고 실시하였다. 그 결과, 우측 식리 상연과 뒤축 일부 편을 접합하여, 결합방법 및 발등 결합에 사용된 원두정의 개수를 확인하였다. 성분 분석결과, 외판 등은 순동에 수은 아말감 금도금을 한 것으로 추정되며, 내판은 순은을 사용하였다. 금동은제식리의 주문양은 봉황문, 연화문, 6엽 화문이며, 전체적으로 연화문의 비율이 높다. 각 판의 결합은 영락사, 금동사, 원두정, 사면정을 사용하였다. 내·외판 결합은 영락사를 사용하였는데, 내측판의 중앙과 후면에는 금동사로만 결합하여 장식 기능과 결합 기능을 구분하여 사용한 것으로 추정된다. 또한 제작과정에서 금동제판과 은제판의 외면에는 광쇠질한 흔적이 확인되지만, 은제판의 내면에서는 확인되지 않아 내면보다 외면의 마무리에 중점을 둔 것으로 추정된다.

• 대한원격탐사학회지
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• 제38권6_4호
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• pp.1901-1910
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• 2022

뉴스페이스(new space) 시대가 도래함에 따라 국내 KOMPSAT-3·3A 위성영상과 해외 위성영상과의 글로벌 융합활용 기술확보가 대두되고 있다. 일반적으로 다중센서 위성영상은 취득 당시의 다양한 외부요소로 인해 영상 간 상대적인 기하오차(relative geometric error)가 발생하며, 이로 인해 위성영상 산출물의 품질이 저하된다. 따라서 본 연구에서는 KOMPSAT-3·3A 위성영상과 해외 위성영상 간 존재하는 상대기하오차를 최소화하기 위한 정밀영상정합(fine-image registration) 방법론을 제안한다. KOMPSAT-3·3A 위성영상과 해외 위성영상 간 중첩영역을 선정한 후 두 영상 간 공간해상도를 통일한다. 이어서, 특징 및 영역 기반 정합기법을 결합한 형태의 하이브리드(hybrid) 정합기법을 이용하여 정합점(tie-point)을 추출한다. 그리고 피라미드(pyramid) 영상 기반의 반복적 정합을 수행하여 정밀영상정합을 수행한다. KOMPSAT-3·3A 위성영상과 Sentinel-2A 및 PlanetScope 영상을 이용하여 제안기법의 정확도 및 성능을 평가하였다. 그 결과, Sentienl-2A 영상 기준 평균 Root Mean Square Error (RMSE) 1.2 pixels, PlanetScope 영상 기준 평균 RMSE 3.59 pixels의 정확도가 도출되었다. 이를 통해 제안기법을 이용하여 효과적으로 정밀영상정합을 수행할 수 있을 것으로 사료된다.

• 대한한방내과학회지
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• 제43권4호
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• pp.582-595
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• 2022

Objectives: To investigate the effects of acupuncture at GV20 and EX-HN1 on cerebral blood flow (CBF) velocity and cerebrovascular reactivity (CVR) in the middle cerebral arteries (MCA) and anterior cerebral arteries (ACA) and to compare the effects to acupuncture at GV20. Methods: The study was a randomized, crossover trial that included 10 healthy men aged 20 to 29 years who underwent acupuncture treatment four times with a washout period of one week. The CBF velocity and CVR were measured by transcranial Doppler sonography (TCD) on both MCAs at the first and second visits, and both ACAs at the third and fourth visits. Participants were randomly assigned to one of two groups (A and B) before the first and third visits. Group A received two phases of acupuncture intervention at a single GV20 point and a combination of GV20 and EX-HN1 acupoints. Group B received the same interventions, but in the reverse order. Results: The increase in CO₂ reactivity was significantly higher for the combination acupoints of GV20 and EX-HN1 than for the GV20 single acupoint in both MCAs (Right: 136 to 178, p=0.017; Left: 127 to 191, p=0.017) and ACAs (Right: 133 to 158, p=0.013; Left: 122 to 168, p=0.025). No significant change was noted in the corrected velocity at PETCO₂ 40 mmHg, blood pressure, or heart rate. Conclusions: The findings suggest that improvement of the CBF in the MCA and ACA after GV20 acupuncture increases when acupuncture is also performed at EX-HN1. These results clinically support the combined use of EX-HN1 and GV20 to treat disorders of MCA and ACA circulation.

• The Journal of Advanced Prosthodontics
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• 제13권4호
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• pp.226-236
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• 2021

PURPOSE. This study aimed to evaluate the effect of incorporating zirconium oxide nanoparticles (nano-ZrO₂) in polymethylmethacrylate (PMMA) denture base resin on flexural properties at different material thicknesses. MATERIALS AND METHODS. Heat polymerized acrylic resin specimens (N = 120) were fabricated and divided into 4 groups according to denture base thickness (2.5 mm, 2.0 mm, 1.5 mm, 1.0 mm). Each group was subdivided into 3 subgroups (n = 10) according to nano-ZrO₂ concentration (0%, 2.5%, and 5%). Flexural strength and elastic modulus were evaluated using a three-point bending test. One-way ANOVA, Tukey's post hoc, and two-way ANOVA were used for data analysis (α = .05). Scanning electron microscopy (SEM) was used for fracture surface analysis and nanoparticles distributions. RESULTS. Groups with 0% nano-ZrO₂ showed no significant difference in the flexural strength as thickness decreased (P = .153). The addition of nano-zirconia significantly increased the flexural strength (P < .001). The highest value was with 5% nano-ZrO₂ and 2 mm-thickness (125.4 ± 18.3 MPa), followed by 5% nano-ZrO₂ and 1.5 mm-thickness (110.3 ± 8.5 MPa). Moreover, the effect of various concentration levels on elastic modulus was statistically significant for 2 mm thickness (P = .001), but the combined effect of thickness and concentration on elastic modulus was insignificant (P = .10). CONCLUSION. Reinforcement of denture base material with nano-ZrO₂ significantly increased flexural strength and modulus of elasticity. Reducing material thickness did not decrease flexural strength when nano-ZrO₂ was incorporated. In clinical practice, when low thickness of denture base material is indicated, PMMA/nano-ZrO₂ could be used with minimum acceptable thickness of 1.5 mm.