• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.282-288
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• 2015

A new energetic thermoplastic elastomer based on the azidated polybutadiene(Az-PBD)/ethylene vinyl acetate copolymer (EVA) blends was prepared, and structure and properties of the blends were invetigated by SEM, DSC, DMA, tensile testing and combustion test. The Az-PBD was synthesized via a two-step process involving the addition reaction of commercially available 1,2-PBD with $Br_2$ and subsequent nucleophilic substitution reaction of the brominated PBD with $NaN_3$. EVA/Az-PBD with 90/10, 80/20, 70/30 (wt/wt) was prepared by a solution blending. SEM, DSC, and DMA results revealed that the blends are partially compatible and Az-PBD is dispersed in continuous EVA matrix. Tensile test showed that modulus and tension set increased while elongation-at-break of the blends decreased with increasing Az-PBD content in the blends, but all the blends showed a elongation at break as high as 700% and a tension set of less than 5%, indicating that the blends are typically elastomeric. Combustion test showed that, with increasing Az-PBD content in the blend, higher energy can be released.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.23-32
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• 2023

The seismic performance of buried PE pipes is reported to be favorable due to their exceptional elongation capacity at break. Although a seismic performance evaluation procedure based on the response displacement method has been summarized in Korea for fusion-bonded PE pipes, there is currently no procedure available for mechanically jointed PE pipes. This article aims to present a seismic performance evaluation procedure based on the response displacement method specifically designed for mechanically jointed PE pipes in Korea. When employing the mechanical joining method for PE pipes, it is recommended to adhere to the evaluation procedure established for segment-type pipes. This involves assessing the stress induced by the pipe, the expansion and contraction strain of the joint, and the bending angle of the pipe joint. Furthermore, the coefficient of inhomogeneity of the soil, which is necessary for estimating the axial strain of the ground, is introduced. Additionally, a computation method for determining lateral displacement and reconsolidation settlement in soil susceptible to liquefaction is proposed. As a result of the sensitivity analysis considering the typical soil condition in Korea, the mechanically jointed PE pipe with a certain quality was shown to have good structural seismic safety when soil liquefaction was not considered. This procedure serves as a valuable tool for seismic design and evaluating the seismic performance of mechanically joined buried PE pipes, which are primarily utilized for connecting small-diameter pipes.

• Journal of The Korean Association of Information Education
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• v.21 no.1
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• pp.13-22
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• 2017

Recently, the emphasis on education of informatics gifted elementary students is to make creative leader in knowledge-based society. It need the high mental faculties and problem solving ability to solve many problem situations for students. In this paper, we developed App Inventor programming education plan. We taught this plan to gifted elementary students and observed the effects of their problem solving ability, self-efficacy and achievement of programing process. In order to achieve the research goals, we designed the appropriate App Inventor programming plan for gifted elementary students and we changed the Learning Model of Renzulli's three step for gifted students to achieve this research goals. Designed learning program was utilized by twenty informatics gifted elementary students for 15 times during five weeks period. In conclusion, we confirmed that App Inventor programming education for gifted elementary students affected the problem solving ability, self-efficacy and achievement of programing process positively.

• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.7-18
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• 2015

In this study, we studied the effect of dissolved cement powder on Carassius auratus by analysis of the morphophysiological changes. The gill exposed to dissolved cement powder showed the thickened primary lamellae and the activity of chloride cells and mucous cells was also significantly increased and the proliferation, separation and clubbing of gill filament was observed in the secondary lamellae. In the kidney tissue, the space in Bowman's capsule was widen and the arrangement of dermis was irregular due to the thinned epidermis in the integument tissue. The activities of antioxidant enzymes and LDH tended to increase with the duration of cement exposure. It was confirmed that the up-regulated proteins were identified as involved in glycolysis and energy metabolism and down-regulated proteins were myofibrillar proteins which were involved in muscle contraction by the cement exposure to the integument. With these results, dissolved cement powder was thought to be a big threat to the survival of the fish because it causes the morphological changes and weakens the physiological activity in C. auratus tissues.

• Childhood Kidney Diseases
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• v.16 no.1
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• pp.21-31
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• 2012

Focal segmental glomerulosclerosis (FSGS) is the name of the primary glomerular disease as well as the terminology to describe the secondary phenomena of any other glomerular diseases. It is characterized by sclerosis, hyalinosis, foam cell infiltration, vacuolar change of podocytes, and halo formation in the glomerulus. Throughout the interstitium, lymphocytes infiltration, tubular atrophy and vascular changes are accompanied. Occasionally, IgM and/or C3 depositions are noted in the sclerotic areas. Electron microscopically, diffuse effacement of foot processes are seen in non-sclerotic area like minimal change disease. Podocyte injury patterns including vacuolar changes are frequently examined. Recently, Columbia group has suggested morphologic classification of FSGS and they demonstrated very good prognosis of tip lesion and poor prognosis of both collapsing and cellular types. However, the pathogenetic classification has been suggested by others; hyperfilteration, podocyte injury, genetic lesions etc. Further studies are necessary to understand and treat this disease.

• Journal of the Korean Chemical Society
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• v.58 no.6
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• pp.667-680
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• 2014

The purpose of this study was to develop teaching stratege focused on Conservational reasoning, Proportional reasoning, Variable-controlling reasoning, Probabilitic reasoning, Correlational reasoning, Combinational reasoning and investigate its effects on enhancing students' logical thinking skills through the science teaching on common education. And the teaching materials was implemented to 110 students in middle school over about six months. The results indicated that the experimental group presented statistically meaningful improvement in logical thinking skills (p<05). Especially, this teaching stratege was effective on Conservational reasoning, Variable-controlling reasoning, Combinational reasoning but was not effective on Proportional reasoning, Probabilitic reasoning, Correlational reasoning (p<.05). Logical thinking according to the teaching strategy skill was not affected by gender, cognitive level, academic achievement (p<.05).

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.21-26
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• 2011

Type-3 cylinder liner has a limitation of machining the standard specimen for fracture toughness test because it has approximately 5 mm in thickness as well as a curvature. Hence, it needs to be employed a miniature specimen test technique to evaluate fracture toughness of the cylinder liner. In this study, small punch (SP) test method was employed to evaluate fracture toughness of the cylinder liner. Load-displacement curve result measured from the SP test showed that the liner material was failed during membrane stretching in the general SP load-displacement curve. Additionally, it was shown that liner material was isotropic although the amount of plastic deformation was different depending on the direction due to manufacturing process characteristics. Fracture toughness, $J_{Ic}$, was evaluated using the SP test data. The value of fracture toughness obtained was $13.0kJ/m^2$. This value was similar to that of the same kind of materials. Therefore, the fracture toughness evaluated using the SP test data was reasonable.

• The Journal of the Korea Contents Association
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• v.11 no.3
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• pp.496-504
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• 2011

The purpose of this study is to inquire the technique of creative problem solving based on OTSM-TRIZ. This is necessary to construct and design the contents that can improve the creative thinking skill for preschool students. So the study contents of this paper are as follows : First, it is to understand the concepts of creative problem solving. Second, it is to examine the theoretical background of OTSM-TRIZ. Third, it is to analysis the educational cases based on OTSM-TRIZ. Particularly, this study investigated Russian educational cases which targeted preschool students. OTSM-TRIZ is problem solving tool that TRIZ had to be transformed into the 'General Theory of Strong Thinking'. At present, this tool is applied on the educational program for thinking creatively at kindergarten, elementary school, middle and high school. And TRIZ is the thinking technique of creative problem solving that can be the tool of inventory solutions by finding and get over the key of contradiction that is necessary to obtain ideal final results of suggested problems.

• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.383-384
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• 2013

본 연구는 스포츠용 탄력 압박 스타킹(Essential compression calf sleeve, SKINS, Australia)을 착용하고 최대 운동을 하였을 때, 하지 부종에 어떠한 효과가 있는지를 알아보고자 한다. 실험 대상자는 젊은 성인 남녀 30명으로(남자 15명, 여자15명) 근 골격계 및 심혈관계에 특이 병력이나 사고에 의한 외상 등이 없었으며, 규칙적으로 운동을 하는 자는 제외하였다. 대상자들의 신체적 특성을 파악하기 위해서 자동 신장계(BSM330, Biospace, Korea)를 사용하였다. 부종정도를 알기위해서 줄자로 운동 전후의 장딴지 근(종아리)의 둘레와 체성분 분석기(InBody 720, Biospace, Korea)를 사용하여 하지의 부종 수치를 측정하였다. 최대의 운동은 호흡가스 분석기와 연결된 트레이드밀(CPEX-1, IRS, Japan)을 사용하여 변형된 BRUCE Protocol TR-3에 따라 호흡 교환율(R) 값이 1.15이상 되거나 all-out 될 때까지 하였다. 실험 대상자들은 동일 집단으로 전이효과를 방지하기 위하여 일주일의 간격을 두고 스포츠 탄력 압박 스타킹 착용 유무에 따른 동일한 실험을 두 번 하였다. 측정은 최대 운동 전후의 장딴지 근(종아리)의 둘레와 부종 수치를 하였다. 스포츠용 탄력 압박 스타킹 착용 유무와 운동 전후를 비교하기 위하여 MANOVA(다변량 분산분석)를 사용하였고 유의수준은 .05로 설정하였다. 탄력 압박 스타킹을 착용한 상태에서 최대 운동 전후의 부종 정도를 측정한 결과 스타킹을 착용하지 않았을 때 운동 전후의 둘레가 유의하게 증가하였고(p<0.05), 스타킹을 착용 하였을 때 운동 전후의 둘레가 유의하게 증가하지 않았다(p>0.05). 부종 수치(세포외액/전체체액)는 탄력 압박 스타킹을 착용하였을 때 오른쪽 다리는 유의하지 않게 감소하였고(p>0.05), 왼쪽 다리는 유의하게 감소하였다(p>0.05). 탄력 압박 스타킹을 착용하고 운동할 경우 하지의 부종 경감에 어느 정도 효과가 있다고 사료된다.

• Childhood Kidney Diseases
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• v.11 no.2
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• pp.152-160
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• 2007

Twenty-six renal allograft biopsies which showed acute rejection and had renal capsule and medulla in the same specimen were selected in order to compare the severity of acute rejection between superficial cortex, deep cortex and medulla. Disregarding the mid cortical region, the superficial cortex was considered as being one-third of the distance from the renal capsule to the medulla and the deep cortex as being that one-third of the cortex which was adjacent to the medulla. Using semiquantitative histologic analysis the following parameters were compared in superficial cortex, deep cortex, and medulla: interstitial inflammation, edema, tubulitis, and acute tubulointerstitial rejection grade. Also, the presence of lymphocyte activation and polymorphonuclear leukocytes was evaluated. Significantly greater histologic changes of acute rejection were found in the deep cortex vs. supeficial cortex for the following parameters: interstitial inflammation(P=0.013), edema (P=0.023) and tubulointerstitial rejection grade(P=0.016). These findings support the view that biopsies in which deep cortex is not included may result in underestimation of the severity of renal allograft rejection.