• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.275-282
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• 2009

The effects of surface treatment method of reinforcing fiber on the bonding strength between carbon fiber reinforced polymer rebar (CFRP rebar) and high strength concrete have been evaluated in this study. The structural PVA fiber is coated with a proprietary hydrophobicoiling agent and crimped type polyolefin based structural synthetic fiber is deformed with a geometrical modification were used for the reinforcing fiber. The compressive tests have been performed to evaluate the strength property of high strength concrete depending on the surface treatment method of fiber. The bonding property between the high strength concrete and the CFRP rebar was evaluated by means of direct bonding test. The test results indicated that the surface treatment method of fiber effect on the bonding behavior of high strength concrete and CFRP rebar. Also, as the development and propagation of splitting cracks were controled by adding fibers into the high strength concrete, the bonding behavior, bond strength and relative bonding strength of CFRP rebar and high strength concrete were significantly improved.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.481-488
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• 2010

Since existing constitutive models developed for confined normal strength concrete overestimate ductility when they are applied to confined high strength concrete, these models cannot be directly applied to confined high strength concrete. In an effort to solve this problem, an accurate stress-strain relationship of the hihg strength concrete needs to be formulated by examining the confinement effects due to increase of the concrete strength. In this study, a constitutive model is developed to express the stress-strain relationship of confined high strength concrete by carrying out regression analysis of the main parameters affection strength and ductile behavior of reinforced high strength concrete columns. Twenty-five test specimens were chosen from the reported experimental studies in the literature. The experimental results of stress-strain relationships of show a good agreement with results of the stress-strain relationships of suggested high strength concrete, covering a strength range between 60 and 124 MPa.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.73-76
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• 2002

The temperature and humidity of dirt-walled storehouse are observed in order to verify the traditional storehouse (main material : soil) during 7days (4th. $Sep{\sim}10th$. Sep). Because the width of the daily variation of temperature is small as $2.5^{\circ}C{\sim}5^{\circ}C$, the reduction of energy supply for low temperature is expected. Because the relative humidity is high and it's variation is small ($4%{\sim}9%$), the inner humidity of dirt-walled storehouse is easily maintained above 80% is expected.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1032-1035
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• 2008

제주도 연악해역의 해일재해의 현황을 파악하기 위하여 제주도 연안해역의 폭풍해일과 기상조에 등에 의한 해일발생 및 피해의 자료를 분석 검토하고 제주도 연안해일의 위험도를 분석하기 위하여 제주도 연안해역을 대상으로 과거 태풍 중 각종 기록경신과 많은 피해규모를 준 태풍들을 대상으로 바람장 및 해일고를 분석 검토하여 태풍의 진로에 따른 해수면 상승을 산정하기위해 폭풍해일 수치모형(POM) 실험을 실시하여 폭풍해일고를 산정하였다. 제주항과 서귀포항 주변해역의 폭풍해일고를 산출하기 위해 16년간($1987{\sim}2003$)까지의 우리나라에 영향을 미친 태풍 중 8개를 선정(Maemi, Rusa, Prapiroon, Olga, Yanni, Janis, Gladys, Thelma)하여 폭풍해일고를 산출하였다. 수치모의 한 결과를 보면, 제주와 서귀포 연안해역에서 발생한 8개의 태풍에 대한 폭풍해일고의 발생시각은 대체적으로 관측된 해일고의 발생시각 보다 약간 늦게 해일이 발생하였지만 전체적인 해일의 시간변화나 크기는 비교적 잘 재현된 것으로 나타났다. 제주항 연안해역의 서귀포항 연안해역보다 높은 해일고를 보였으며, 해일고는 제주항, 서귀포항 모두 1m를 넘지 않았다. 제주항이 서귀포항에 비해 약간 높게 나온 이유는 태풍의 위치, 지형 및 수심, 태풍이 통과할 당시의 조석상황 등의 차이인 것으로 사료된다. 또한, 제주항과 서귀포항 연안해역이 폭풍해일고가 서해안이나 남해안에 비해 작게 나타났는데, 이는 제주도 해안선이 비교적 평탄하고 평행하게 이루어 졌으며 남해안에 비해 수심이 깊고 만의 형태나 V자형 및 긴내만이 발달한 지형이 없기 때문인 것으로 사료된다. 보다 정밀한 예측을 위해서는 정밀한 수심자료 및 격자를 이용한 계산의 결과가 필요하며, 연안개발로 인한 지형과 수심변화에 따른 지속적인 수치해도 DB구축이 요구된다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.605-608
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• 2008

This study investigated fundamental properties corresponding to mixtures for the high strength, and their properties of spalling prevention after a fire test. The results were summarized as following. For the flowability of using mixtures for the high strength, the target flow was satisfied with a small quantity of high performance reducing water agent to compare with silica fume. For the compressive strength in the case of using mixtures for the high strength, it was higher to compare with silica fume at 7 days, so it was proved that using mixtures for the high strength was profitable to prevent early frost damage. The compressive strength at the 28 days of silica fume and mixtures for the high strength were similar. There was no reduced tendency at the compressive strength according fiber contents, so it found out that the bonding strength between the fiber and concrete was hardly effective. For the spalling properties, the specimens without fibers were destroyed, however using over 0.05% of NY and PP fibers was effective to prevent spalling on the high strength concrete.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.53-60
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• 2006

The shear failure modes of reinforced concrete members using high-strength materials (high-strength concrete and high-strength steel) are different to those of reinforced concrete members using normal-strength materials. The reinforced concrete members using high-strength materials are inclined to fail due to concrete crushing before the shear reinforcing bar reaches its yield strength. This paper presents an evaluation equation to calculate the maximum shear reinforcement ratio based on the material stresses and strains when the reinforced concrete members fail in shear. The maximum shear reinforcement ratio calculated by the proposed equation increases as the compressive strength of concrete increases. Test results of 97 reinforced concrete members reported in the technical literatures are used to check the validity of the proposed equation. The comparison between the test results and the ratio calculated using the proposed equation indicated that the shear failure modes depended on the interaction between the amount of shear reinforcement and the compressive strength of concrete.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.255-263
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• 2012

High frequency sounds disrupt physiological processes, such as feeding behavior, development and immune responses of Spodoptera exigua. We analyzed high frequency sounds with respect to biochemical changes in S. exigua. High frequency sound (5,000 Hz, 95 dB) suppressed protein synthesis and secretion of midgut epithelium. It also significantly inhibited a digestive enzyme activity of phospholipase $A_2$. The gene expression of three different heat shock proteins and apolipophorin III was altered, particularly in midgut tissue in response to high frequency sound treatments. High frequency sound treatments significantly increased sugar and lipid levels in hemolymph plasma. These results suggest that high frequency sounds are a physiological stress that induces biochemical changes in S. exigua.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.363-369
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• 2018

The purpose of this study was to perform exercise program for patients with borderline hypertension and hypertension. And the change of the metabolic syndrome index. This study was performed for 15 weeks on borderline hypertension, hypertension patients. 28 subjects participated in the exercise program for 40 minutes, three times a week for 15 weeks. The following conclusions were obtained. First, there was a significant correlation between the prevalence of metabolic syndrome before and after the exercise program. Second, there were significant differences in body weight, muscle mass, fat mass, BMI, waist circumference, diastolic blood pressure, and blood sugar before and after 15 weeks of exercise program. This can lead to improved metabolic syndrome indicators in hypertensive patients with a muscle extension exercise program.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.72-75
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• 2012

In this paper, high-efficiency DC-AC converter is implemented for the wireless power transmission. The DC-AC converter is implemented by combining the oscillator and power amplifier. Because the conversion efficiency of wireless power transmitter is strongly affected by the efficiency of power amplifier, the high-efficiency power amplifier is implemented by using the Class-E amplifier structure. Also, because the output power of oscillator connected to the input stage of power amplifier is low, high-gain two-stages power amplifier using the drive amplifier is implemented to realize the high-output power DC-AC converter. The dual band harmonic suppression filter is implemented to suppress 2nd, 3rd harmonics of 13.56 MHz. The output power and conversion efficiency of DC-AC converter are 40 dBm and 80.2 % at the operation frequency of 13.56 MHz.

• 한국HCI학회:학술대회논문집
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• 2006.02b
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• pp.795-802
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• 2006

현대의 소비자는 더 이상 단순히 감성적 소구에 의해서나 기술적 기능을 제공하는 것으로 제품을 구매하지 않는다. 제품의 결정은 사용자와 제품 간의 상호작용에 따른 정서, 인지, 행위 등에 의한 총체적인 경험에 의한 것이며, 그러한 소비자들의 경험은 지리적, 역사적 전통으로 고착된 문화적 특성이 제품을 통한 사용자 경험의 기저에서 작용함으로써 문화권 별, 국가 별로 각기 다르게 구성된다. 특별히 음식 문화는 어느 나라이든 자연 조건의 영향과 함께 오랜 역사 속에서 형성되었기 때문에 독특하고 다양한 문화적 차이를 지니고 있으며 이러한 문화적 차이는 냉장고 사용에 있어서 다양한 사용행태를 구분 짓는다. 따라서 본 연구를 통해 식품 종류에 의한 영향뿐 아니라 내부 공간 활용의 패턴, 냉장고 환경 설정에 대한 능동적인 태도, 냉장고에서 제공하는 파티션이나 옵션에 대한 수용 정도, 식품의 정리 원칙에 대한 준수 정도 등에 따른 사용행태 간의 차이점을 발견하고, 차별적 사용행태의 기저에 존재하는 문화적 요인을 분석하여 문화적 차이가 사용자의 경험에 영향을 끼치게 됨으로 인하여 냉장고 디자인에 어떠한 변화를 초래하는지 그 연관성을 밝혀내고자 한다. 보다 실제적인 용도로 활용 가능하도록 냉장고 제작의 상업적인 측면을 고려하여 냉장고 내상의 레이아웃에 중점을 두어 본 연구를 진행하였다. 본 연구는 설문과 현장 관찰을 통해 정량적 관찰을 중심으로 분석하였다. 두 국가의 문화 비교를 위한 설문은 이미 여러 연구자료에 의해 검증된 Trompenaars의 문화 변수를 바탕으로 제작 하였다. 또한 정량적 연구에서 발견될 수 없는 문화권 별 여러 특징들에 대한 데이터를 구체적으로 수집하기 위하여 정성적인 연구 방식의 일환으로 실제 관찰 및 사용자 인터뷰를 실시하였으며, 이를 통하여 현상의 원인 및 사용자의 의도를 파악하도록 연구를 진행하였다.