• 대한기계학회논문집A
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• 제32권12호
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• pp.1132-1139
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• 2008

The aim of this study is to apply shape optimization technique for the repair of aging airframe components, which may extend fatigue life substantially. Free-form optimum shapes of a cracked part to be reworked or replaced are investigated with the objective to minimize the peak local stress concentration or fatigue-damage. Iterative non-gradient method, which is based on an analogy with biological growth, is employed by incorporating the robust optimization method to take account of the stochastic nature of the loading conditions. Numerical examples of optimal hole shape in a flat plate are presented to validate the proposed method. The method is then applied to determine the reworked or replacement shape for the repair of a cracked rib in the rear assembly wing body of aircraft.

• 한국해양바이오학회지
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• 제10권2호
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• pp.34-43
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• 2018

Silicon has become of increasing importance as the basic element of many high-technology products. Its synthesis is very difficult requiring high temperature solid-state reactions (> $1000^{\circ}C$) or lower temperature methods ($100-200^{\circ}C$) involving hydrothermal and solvothermal reactions under extreme pH conditions. In nature, on the other hand, a wide range of living organisms have collectively evolved the means of biosilicification at the astounding rate of gigatons/year. This is impressive because biosilicification in these organisms occurs under mild physiological conditions. Marine sponges possess the ability to sequester soluble silicon sources from their environments and assemble them into intricate 3D architecture. The advent of molecular biology has recently made it possible to glean molecular information about biosilicification from these systems and it turned out that enzyme silicatein is the core of biosilicification. In this review, biosilicification regulated by silicatein and its mechanism are described. Also, production of silicatein through recombinant technology and several applications of recombinant silicatein are described including immobilization of silicatein, formation of Au or Ag nanoparticles on nanowires, nanolithography approaches, core-shell materials, encapsulation, bone replacement materials, and microstructured optical fibers.

• 한국산학기술학회논문지
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• 제21권4호
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• pp.156-163
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• 2020

본 연구는 구급대원을 대상으로 현 출동벨에 대한 스트레스를 파악하고 출동벨에 대한 요구 및 개선점을 파악하여 현실적으로 적용 가능한 출동벨 변경을 위한 기초자료로 제공하기 위한 조사연구이다. 자료 수집은 2019년 8월 28일부터 9월 21일까지 자발적 의사에 의해 연구에 동의하는 대상자 267명을 대상으로 온라인 설문조사로 수집되었다. 연구도구는 구조화된 설문지를 이용하였다. 연구결과는 SPSS/WIN 23.0을 사용하여 평균과 표준편차, 백분율 및 빈도 분석, 독립표본 t-검정으로 분석하였다. 현 근무지의 구급 출동벨 유형은 복합형이 143명(53.4%)으로 가장 많았고 출동벨에 대한 부정적인 생각이 132명(49.4%)으로 높아 주기적인 교체가 필요하다고 사료된다. 상황별 스트레스로는 취침 중에 출동벨을 들었을 때 4.35±0.94로 가장 높았다. 일평균 구급출동 횟수에 따른 취침 중 스트레스에서는 9회 이상과 9회 미만 출동하는 그룹이 통계학적으로 유의미한 차이를 보였다(p<0.05). 구급대원이 원하는 출동벨의 유형으로는 '부드러운 음악'과 '자연의 소리' 등으로 현 출동벨의 교체를 원하는 비율이 168명(62.9%)으로 절반 이상을 차지하였고, 24개월 이내로 주기적인 출동벨의 교체를 원하는 비율도 163명(91.6%)으로 높기 때문에 출동벨에 대한 개선이 필요할 것으로 사료된다.

• 한국전통조경학회지
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• 제34권4호
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• pp.89-97
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• 2016

본 연구는 특정한 시대에 장백산 지역에 조성된 제사공간을 문화경관의 관점으로 바라보면서 장백산의 신성성이 역사 속에서의 변화과정과 정권의 교체와 민족의 변화 속에서도 신성성이 유지된 이유에 대하여 해석했다. 본 연구의 결과를 요약하면 다음과 같다. 첫째, 청나라에서 중화민국시기로 과도하면서 겪은 정권의 교체와 민족의 다양성, 그리고 문화의 수용성으로 인하여 장백산의 제사성격과 신적대상이 변화했다. 둘째, 청나라의 황가 제사공간인 망제전(望祭殿)은 권위적인 공간으로 만족만의 유일한 제사공간과 문화를 형성했고 중화민국 시기에는 한족의 이주와 정착과정을 겪으면서 방산인 사이에서 새로운 민간신앙이 탄생했으며 따라서 제사공간인 여래사(如來寺), 산신노파두묘(山神老把頭廟)가 조성되었다. 셋째, 제사공간과 장백산을 공간적으로 보면 망제전은 수직적인 공간으로 권력적인 공간이고 여래사와 팔괘묘는 장백산과 수평적인 공간에 입지되어 순종적인 공간으로 나타났다. 넷째, 제사의례를 보면 청나라의 망제전은 만족만의 유일한 제사의례 이지만 황권의 폐지에 따라 단절되었다. 현재는 민간제사의례가 일상화 되어있고 청나라의 제사의례는 형식적으로만 진행된다. 결론적으로 보면 역사적으로 장백산에 대한 신성성은 변하지 않았다. 하지만 장백산 제사공간은 청나라의 단일한 제사문화에서 정권의 교체와 다민족의 문화에 대한 수용을 거쳐 변화하였다. 현재는 상호수용을 통하여 중첩된 제사공간과 문화를 형성하였다.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1310-1314
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• 2006

Sulfur-substituted $LiMn_{0.9}Cr_{0.1}O_{2-x}S_x$ $(0\;\leq\;x\;\leq\;0.1)$ layered oxides have been prepared by solid state reaction under inert atmosphere. From powder X-ray diffraction analyses, all the present lithium manganates were found to be crystallized with monoclinic-layered structure. Electrochemical measurements clearly demonstrated that, in comparison with the pristine $LiMn_{0.9}Cr_{0.1}O_2$, the sulfur-substituted derivatives exhibit smaller discharge capacities for the entire cycle range but the recovery of discharge capacity after the initial several cycles becomes faster upon sulfur substitution. The effect of the sulfur substitution on the chemical bonding nature of $LiMn_{0.9}Cr_{0.1}O_{2-x}S_x$has been investigated using X-ray absorption spectroscopic (XAS) analyses at Mn and Cr K-edges. According to Mn K-edge XAS results, the trivalent oxidation state of manganese ion remains unchanged before and after the substitution whereas the local structure around manganese ions becomes more distorted with increasing the substitution rate of sulfur. On the other hand, the replacement of oxygen with sulfur has negligible influence on the local atomic arrangement around chromium ions, which is surely due to the high octahedral stabilization energy of $Cr^{+III} $ ions. Based on the present experimental findings, we have suggested that the decrease of discharge capacity upon sulfur substitution is ascribable to the enhanced structural distortion of $MnO_6$ octahedra and/or to the formation of covalent Li-S bonds, and the accompanying improvement of cyclability would be related to the depression of Mn migration and/or to the pillaring effect of larger sulfur anion.

• 한국건축시공학회지
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• 제14권1호
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• pp.94-101
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• 2014

굴과 꼬막과 같은 패각의 일부는 채묘종과 비료 등으로 재활용 되기도 하나, 대부분 인근 해안에 적치 되거나 불법 매립되고 있는 실정이다. 본 연구에서는 패각의 기초물성을 측정하고 패각을 시멘트 모르터에 혼입할 수 있는 가능성을 평가하고자 하였다. 그 결과 패각을 25% 혼입한 시멘트 모르터의 경우 흡수율과 압축강도가 Plain과 유사하게 측정되었다. 반면 굴패각을 25% 혼입한 경우 Plain에 비해 압축강도가 35% 저하되었으며, 흡수율은 2배로 증가하였다. 따라서 굴을 제외한 나머지 패각을 25% 범위 내에서 시멘트 모르터에 혼입하여 사용하는 것은 가능할 것으로 사료된다. 하지만 굴의 경우 다양한 혼입율을 적용한 추가 실험이 요구될 것으로 판단된다.

• Geomechanics and Engineering
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• 제22권3호
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• pp.227-236
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• 2020

Expansive soils are renowned for their swelling-shrinkage property and these volumetric changes resultantly cause huge damage to civil infrastructures. Likewise, subgrades consisting of expansive soils instigate serviceability failures in pavements across various regions of Pakistan and worldwide. This study presents the use of polypropylene fibers to improve the engineering properties of a local swelling soil. The moisture-density relationship, unconfined compressive strength (UCS) and elastic modulus (E₅₀), California bearing ratio (CBR) and one-dimensional consolidation behavior of the soil treated with 0, 0.2, 0.4, 0.6 and 0.8% fibers have been investigated in this study. It is found that the maximum dry density of reinforced soil slightly decreased by 2.8% due to replacement of heavier soil particles by light-weight fibers and the optimum moisture content remained almost unaffected due to non-absorbent nature of the fibers. A significant improvement has been observed in UCS (an increase of 279%), E₅₀ (an increase of 113.6%) and CBR value (an increase of 94.4% under unsoaked and an increase of 55.6% under soaked conditions) of the soil reinforced with 0.4% fibers, thereby providing a better quality subgrade for the construction of pavements on such soils. Free swell and swell pressure of the soil also significantly reduced (94.4% and 87.9%, respectively) with the addition of 0.8% fibers and eventually converting the medium swelling soil to a low swelling class. Similarly, the compression and rebound indices also reduced by 69.9% and 88%, respectively with fiber inclusion of 0.8%. From the experimental evaluations, it emerges that polypropylene fiber has great potential as a low cost and sustainable stabilizing material for widespread swelling soils.

• 무역상무연구
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• 제69권
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• pp.407-426
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• 2016

The Marine Insurance Act 1906 (MIA 1906) has been a successful piece of legislation, having rarely been amended and having established, or served as an influence in the development of, the basis of marine insurance legislation in several countries. However, it has been recognised that some parts of the MIA 1906 have begun to show their antiquated nature, especially where established principles which were once thought to reflect undoubted propositions of law are now being openly criticised. Since 2006, the Law Commission and Scottish Law Commission (the 'Law Commissions') have been engaged in a major review of insurance contract law, finally leading to the Insurance Act 2015. The Insurance Act 2015 received Royal Assent on 12 February 2015, and was based primarily on the joint recommendations of the Law Commissions. The 2015 Act made substantial changes to several main areas of marine insurance law & practice: (i) the replacement of the pre-contractual duty of disclosure with a duty to make a "fair presentation of the risk"; (ii) the abolition of the "insurance warranty" under the Marine Insurance Act 1906, s.33, and provision of a new default remedy of suspension of liability until the breach is cured; (iii) partial codification of the fraudulent claims rule in insurance contract law, etc. The Act did not provide for any new statutory duty for insurers to investigate or pay claims in a timely fashion, although this may be revisited in the next Parliament. Moreover, the Law Commissions have reopened their consideration of the doctrine of insurable interest. The 2015Actmay not then signal the end of the legislative programme in this area.

• 한국주거학회논문집
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• 제25권2호
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• pp.19-26
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• 2014

The number of elderly who wants to access to Nursing Homes (NH) will increase due to the rapid aging society and domestic changes. Those who move into NH expect 24/7 care service in safe environment. Providing space free from danger, especially from fall, for the frail elderly is essential. The purpose of this study is to categorize performance needs of flooring materials in the aspect of safety, and analyze materials so that adequate ones for each space in NH can be suggested. Performance needs are as follows; slip resistance (dry/wet), fire resistance, resilience, water resistance, soil retardant, anti-bacterial, gloss, sound absorbtion. maintenance, durability, ease replacement, color and pattern variety, visual and tactual texture, tactile warmth, IAQ, sustainable material (before use), impact to nature (after use). They are categorized under function, economy, sensibility and sustainability. It was found that there are better materials than common ones that has been used repeatedly in NHs, such as vinyl sheets and VCT. In overall, Cork flooring and nylon carpet met all four categories, followed by wool carpet, rubber and linoleum. For bedroom, wood flooring, Cork, rubber, wool carpet, nylon carpets were suggested. In bathroom with shower, rubber, vinyl sheet and porcelain tiles were safe materials. As living/dining room and corridor floors, wool carpet, nylon carpet, cork flooring would be excellent as they are resilient and durable. The result of this paper can be used by both NH managers and material companies, resulting better quality of life of the elderly by providing safe environment.

• KIEAE Journal
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• 제8권4호
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• pp.63-69
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• 2008

The thesis is a comparative analysis of Infill Technologies between Korea's long-life Mock-up House, a study driven by 'Durability and Flexibility of Long-life Housing Technology Development' of R&D, and Japan's KSI experimental house, the major example of Japan's long-llfe housing. In terms of the domestic Mock-up House, a system of building the floor first was applied. The floor material of each housing unit required a development of dry heating component that is partially substitutable in order to avoid conflict with the finishing. Also, a development of a floor system that can counteract against the construction inaccuracy was required. In the Case of an outer wall, need to make the wall with the chassis. In the case of ceiling, need to develop the double ceiling system which is good for sound insulation. Also, in comparison to KSI experimental house in Japan, it would require to develop a wiring system of the ceiling which can react to the movement of the wall. Especially, to assure the flexible nature of an internal wall, it would desperately require the research and development of the products related to components and flexible system of mechanical/electrical/communication parts as well as supporting institutionalized system for this development. Furthermore, for KSI experimental house in Japan, it would be necessary to formulate a construction manual as well as a systematic and practical planning guide to invent a new interface rule which will secure simplicity of assembling, dismantling, installation and replacement of architectural components for which research development is quite insignificant at the moment. This effort will have to continue to give a solid direction for better application of such reference manual during construction and development of long life span apartment by public sector as well as private corporations.