• 한국의류학회지
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• 제23권6호
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• pp.853-863
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• 1999

the change of physical properties (thickness, weight, air permeability) and mechanical properties(abrasion resistance breaking load and displacement) of samples were determined after heat exposure by a RPP tester. The effect of exposure time and heat flux intensity on the changes and the relationship between physical properties and mechanical properties were investigated. FR treated cotton Kevlar/PBI and Nomex with different structureal characteristics were chosen for specimens. The changes of physical properties and mechanical properties were calculated based on their initial values before heat exposure. The longer exposure time and the high heat flux intensity the more changes of those properties. Heat flux intensity was more effective on the changes, The showed to be affected by an interplay of shrinkage and pyrolysis products loss. The changes of thickness and abrasion resistance showed to be higher for plain weave fabric and those of air permeabiliyt and breaking load and displacement for twill weave fabric. While FR treated cotton which have high RPP value experienced serious and detrimental changes after heat exposure Kevlar/PBI which has low RPP value showed no high changes. In conclusion it could be confirmed that when total performance of a protective clothing is estimated retention capability of physical and mechanical properties after heat exposure as well as RPP value must be considered.

• 한국작물학회지
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• 제11권
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• pp.105-117
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• 1972

본연구는 맥류의 도복에 관여하는 주요형질의 상호관계를 구명함과 아울러 주요 대소맥 품종의 내도복성정도를 분류하고, 내도복성 품종 선발의 기준을 인정하여 보고자 한 것이며, 그 결과를 요약하면 다음과 같다. 1. 포장도복과 도복지수는 고도의 정의 상관(대맥 r=0.44-0.67 소맥 r=0.46-0.68)이 있으며 지상부 Bending moment에 간자체의 정도를 가미한 지수로서 도복저항성 검정에 가장 유효하다. 2. 간의 Bending stiffness를 표시하는 좌절시 Bending moment와 단면 2차 moment와는 정의 높은 상관(대백 r=0.59, 소맥 r=0.46-0.53)을 보였다. 3. 간의 Bending stiffness(좌절시 Bending moment 단면 2차 moment)와 간에의 건물집적량을 표시하는 단위간건물중과는 높은 정의 상관 (대맥 r=0.35-1.40, 소맥 r=0.33-0.76)을 보였다. 4. 도복지수와 단위간건물중 (대맥 r=-0.51～-0.70, 소맥 r=-0.65～-0.83) 좌절시 Bending moment (대맥 r=-0.29～-0.69, 소맥 r=-0.54～-0.89)과는 특히 높은 부의 상관을 보였으며, 소맥의 경우는 좌절하중, 단면 2차 moment, 단면계수와는 높은 부의 상관을 보였다. 5. 간외경은 간내경보다 간의 물리적 특성과 상관이 높으며 좌절하중 (대맥 r=0.42-0.56, 소맥 r=0.39-0.44), 좌절시 Bending moment (대맥 r=0.40-0.41, 소맥 r=0.38-0.49), 단면 2차 moment (대맥 r=0.56-0.97, 소맥 r=0.0.28-0.28), 단면계수(소맥 r=0.22-0.96)와는 정의 높은 상관이 있었고, 간벽후와 물리적특성과도 정의 상관을 보였다. 6. 간장은 포장도복과는 품종군에 따라서는 정의 상관은 보이나, 간의 강도를 고려한다면 내도복저항성품종 선발의 지표로서 이용하기는 어려울 것으로 보인다. 7. 대소맥의 많은 품종의 내도복성 정도를 분류한 결과, 한국품종중 대맥은 내도복저항성품종이 많고, 대맥은 내도복성인 품종의 분포가 대맥보다 적었으나, 일본품종들을 대소맥 모두 내도복저항성인 품종이 많았다. 8. 내도복저항성인 품종의 선발을 위하여는 도복지수가 대맥 1.67 소맥 1.76 정도 이하인 것은 고도의 저항성이 있었다.

• 한국소음진동공학회논문집
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• 제15권11호
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• pp.1248-1254
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• 2005

L/UL(Load/unload) mechanism has been widely used in SFF(Small form factor) HDD because L/UL technology has many advantages such as an increase of areal density, reduction of power consumption and improvement of shock resistance. In this system, the most important design goal is no slider-disk contact and fast air-hearing breaking during L/UL process. To do so, we should consider many design parameters related to L/UL system. The ramp shape is the most dominant component among parameters which dramatically affect the L/UL performance. This paper makes an advanced ramp model using ANSYS/LS-DYNA. Through this FE model, this paper investigates the effect of initial ramp slope and location of air-bearing breaking. From the experiment for three different ramps, we also verify that experimental results agree with simulation results. We conclude that the ramp design should have small ramp slope at the moment which a suspension tap contacts with ramp and large ramp slope after air-bearing breaking in order to improve L/UL Performance.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.93-93
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• 2017

To develop rice cultivars with increased biomass and grain yield, superior lodging resistance is an essential trait. The new breeding approach can be adopted for the improvement of stem lodging resistance by enhancing culm strength. The resistance to breaking type lodging is attributed to bending moment of basal culm (M), which is composed of the section modulus (SM) and bending stress (BS). The resistance to the bending type lodging is attributed to flexural rigidity (FR) of stem, which is composed of the secondary moment of inertia (SMI) and Young's modulus (YM). Starch and cell wall components such as cellulose, hemicellulose and lignin also play a significant role in physical strength of culm, and thus affect lodging. Leaf Star has a superior lodging resistance due to its thick and stiff culm because of its high M and FR compared with Koshihikari. Furthermore, Leaf Star contains high densities of hemicellulose, cellulose and low lignin density in culm compared with Koshihikari. In this study, we performed QTL analysis for these traits associated with culm strength, using 94 recombinant inbred lines (RILs, $F_8$), derived from a cross between Leaf Star and Koshihikari. The SM in the RILs showed a continuous distribution. QTLs for SM were detected on chrs.2, 3 and 10. Leaf Star alleles increased SM on chrs. 2 and 3, but Koshihikari allele increased on chr.10. These QTLs overlapped with those QTLs identified using backcrossed inbred line derived from a cross between Chugoku 117 and Koshihikari, the parents of Leaf Star. The FR in Leaf Star was higher than that in Koshihikari due to the larger SMI and YM. 3 QTLs for SMI were detected on chrs.2, 3 and 10. Leaf Star alleles increased SMI on chrs.2 and 3, and Koshihikari alleles increased on chr.10. One QTL on chr.3 and two QTLs on chr.5 for hollocelulose content were detected with Leaf Star alleles contribution. Moreover, two QTLs were detected for hemicellulose density on chrs.3 and 5. Leaf Star allele increased hemicellulose density on chr.5, and Koshihikari allele increased on chr.3. Furthermore, two QTLs for cellulose density were detected on chr.5, and one QTL on chr.2. For starch content, one QTL on chr.3 and two QTLs on chr.5 with Leaf Star alleles contribution were detected. TULK-6 carrying a chromosome segment of Leaf Star on chr.5 in the Koshihikari genetic background showed higher densities of starch and hemicellulose than those in Koshihikari. These results suggest that the detected QTLs for culm strength could be utilized for the improvement of lodging resistance in rice by marker-assisted selection.

• 한국노년학
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• 제31권2호
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• pp.303-315
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• 2011

본 연구의 목적은 12주간 저항성훈련에 따른 노화 흰쥐의 골밀도 및 골대사 관련 지표에 미치는 영향을 관찰하는 것이다. 생후 64 주령의 Sprague-Dawley계 노화 흰쥐(체중 565±3.12)를 대조군(n=10)과 저항성 훈련군(부하 없는 저항성 훈련군(n=10)과 부하 있는 저항성 훈련군(n=10)으로 분류하여 주 4회 12주간 사다리 오르기 훈련을 실시한 후 골밀도 및 골대사 관련 지표의 변화를 측정한 결과 다음과 같은 결론을 얻었다. 대퇴골의 회분 및 칼슘 햠량은 부하 있는 저항성 훈련군>부하 없는 저항성 훈련군>대조군 순으로 유의하게 증가하였으며, 세 집단간 유의한 차이가 나타났다. 인지질 함량은 부하 있는 저항성 훈련군>부하 없는 저항성 훈련군, 부하 있는 저항성 훈련군>대조군 순서로 나타났는데, 대조군에 비교하여 부하 있는 저항성 훈련군에서만 유의한 차이가 나타났다. 골강도와 osteocalcin 농도는 부하 있는 저항성 훈련군>부하 없는 저항성 훈련군>대조군 순으로 유의하게 증가하였으며, 세 집단간 유의한 차이가 나타났다. 본 연구를 종합하면 노화 흰쥐에서 12주간 저항성훈련은 대퇴골밀도와 골대사관련 지표에 유익한 효과를 나타내는데 이러한 결과는 저항성훈련으로 인한 골밀도의 증가는 골재흡수의 지표인 osteocalcin 과 골의 기계적구조의 변화뿐만 아니라 훈련의 강도(training intensity)가 중요한 매개 요인임을 알 수 있었다.

• Journal of Nutrition and Health
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• 제34권5호
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• pp.541-546
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• 2001

This study examined the effect of various types of exercise on bone formation and resorption in rat. Five-week-old male Sprague-Daweley rats were randomly assigned to one of four groups with 10 animals in each; Control, Treadmill, Swimming, Resistance. The exercise regimen consisted of treadmill running at 25m/min, 1 hr per day, 5 days a week, and swimming for 1 hr per day, 5 days a week. Resistant exercise type with weight-bearing was designed to extend lower and upper extremities in order to feed the diet and water. Food intake showed no significant difference among groups but body weight gain and food efficiency were significantly increased in Control group as compared with exercise groups. Femur and tibia length and weight were higher in Control group and the density of therm tended to be higher in exercise groups than Control group, but this difference was not statistically significant. The breaking force of femur was the highest in Swimming group and tibia was the highest in Resistance group among groups, while there was no signigicant difference among the exercise groups. The calcium content of femur was significantly increased in Resistance group than the other groups. Calcium intake and urinary calcium showed no significant difference among groups, while calcium absorption and retention were significantly higher in exercise group than Control group. In conclusion, exercise training enhanced bone formation due to the positive effect on metabolism of calcium and bone which were different according to the types of exercise. (Korean J Nutrition 34(5) : 541∼546, 2001)

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.453-454
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• 2011

With the transmission line the ratio of lightning breakdown the while whole breaking down is occupying a high share with average 72%, is a tendency which increases continuously. In order decreasing the back flashover faults from like this lightning breakdown, it is very important to maintain grounding resistance of tower below target. In this paper, we synthetically analyzed the grounding resistance reduction effect of tower foundation and standard ground connection from construction site, and investigated efficiency for ways to increase the length of counter poise and expand the size of conductivity concrete materials.

• Fibers and Polymers
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• 제5권1호
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• pp.25-30
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• 2004

The present paper reports the impact of thermal treatment on the characteristics of core-sheath type hybrid technical yarns. The core-sheath type hybrid yams are prepared using DREF-III technology. Polyester and glass multifilaments are used as core components whereas the cotton and polyester staple fibers are the sheath components wrapped around the core filament with different proportions to form a hybrid structure. The thermal treatment is carried out both in dry and in wet state under relaxed condition and the thermal shrinkage, sheath-slipping resistance and tensile and bending properties of hybrid yarns have been studied. Thermal treatment markedly increases the thermal shrinkage and sheath-slipping resistance of hybrid yarns with polyester multifilament in core, but insignificant effect for yarns with glass multifilament in core. Breaking elongation of hybrid yams with polyester multifilament in core increases with treatment temperature. The hybrid yarns with glass multifilament in core are least affected by thermal treatment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.216-219
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• 1996

Polytetrafluoroethylene is very suitable for insulation materials because of it's high thermal and chemical stability, high electrical resistance and low loss factor. But almost all kinds of pure fluoroplastic cannot endure long time in the high temperature arc environment breaking high voltage and current In this study, inorganic materials such as BN, TiO$_2$ and Al$_2$O$_3$ were filled in the polytetrafluoroethylene to improve arc resistance. The electrical properties, arc resistant properties and light reflectance of the composites were investigated.

• 대한조선학회논문집
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• 제57권1호
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• pp.23-34
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• 2020

This paper covers the development of prediction techniques for ice load on ice-breakers operating in continuous ice-breaking under level ice conditions using particle-based continuum mechanics. Ice is assumed to be a linear elastic material until the fracture occurs. The maximum normal stress theory is used for the criterion of fracture. The location of the crack can be expressed using a local scalar function consisting of the gradient of the first principal stress and the corresponding eigen-vector. This expression is used to determine the relative position of particle pair to the new crack. The Hertz contact model is introduced to consider the collisions between ice fragments and the collisions between hull and ice fragments. In order to verify the developed technique, the simulation results for the three-point bending problems of ice-specimen and the continuous ice-breaking problem around a wedge-type model ship with bow angle of 20° are compared with the experimental results carrying out at Korea Research Institute of Ships and Ocean Engineering (KRISO).