• 한국기계가공학회지
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• 제19권2호
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• pp.81-88
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• 2020

The damping hinge of a built-in refrigerator was examined in terms of its stress and fatigue life. Analysis of the initial design showed that stress concentration occurred at the concave surface of the hinge lever, which was broken during the door opening-and-closing endurance test of the prototype. The maximum von Mises stress at this location exceeded the yield strength. In addition, Goodman fatigue analysis of the initial design showed that the fatigue life at this location was consistent with the failure observed during the endurance test. Based on these results, an improved design for the damping hinge was derived. Analysis of this improved design showed that the stress concentration in the hinge lever of the initial design was eliminated. In this case, the maximum stress occurred at the position where the hinge lever was in contact with the door stopping pin, and the maximum von Mises stress was smaller than the yield strength. Goodman fatigue analysis of the improved design indicated that the fatigue life of the entire damping hinge was infinite. It was therefore concluded that the improved design does not suffer from fatigue damage during the endurance test.

• 한국의류산업학회지
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• 제7권1호
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• pp.96-100
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• 2005

The bleaching is one of the worst factors which leads to the damage of the human hair. The cuticle of the human hair is injured by the alkali that is one of the chief ingredients of a bleaching agent. The alkali component of the bleaching solution chemically reacts with human hair, reducing the tenacity and dissolving the cuticle layer. The purpose of this study is to examine the effects of bleaching time and temperature on the physical properties and morphology. The results were as follows. 1. The stress-strain curves for human hair indicated the three distinct regions, such as Hookean region, Yield region and post-Yield region. The tenacity of hair is reduced gradually with an increase of bleaching time. Under these same conditions, elongation of the hair increased. 2. The greatest drop in tenacity for hair occured between $40^{\circ}C$ and $60^{\circ}C$ of bleaching temperature. 3. Compared with the virgin hair, bleached hair showed a slower rate of weight reduction in the TGA thermogram. The rate decreased gradually as the bleaching time and temperature increased. 4. As the bleaching conditions reached time and temperature extremes, the human hair cuticle became more damaged. The cuticle layers seemed to have dissolved, as seen in the SEM photographs.

• 한국토양비료학회지
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• 제48권3호
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• pp.213-217
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• 2015

Soil moisture shortage can reduce yield of waxy corn because maize is one of the sensitive crops to the drought stress. Farmers cannot irrigate due to limited water resource and irrigating facilities although applying water is the most effective practice to solve the drought problem. The study was conducted to investigate the pre-treatment effect of salicylic acid on reducing drought damage of waxy corn (Zea mays L.). Salicylic acid at concentration of 0.2 mM was applied at seven-leaf stage or ten-leaf stage three times. Drought stress was imposed by withholding irrigation from 11 days before anthesis to 10 days after anthesis. Application of salicylic acid significantly increased ear length by 11.0~12.3% and yield by 8.8~11.3% compared with non-treated control, indicating that the drought injuries of waxy corn can be alleviated through pre-treatment of salicylic acid at the vegetative stage.

• 소성∙가공
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• 제16권4호
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• pp.254-259
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• 2007

Dent resistance is an important characteristic to avoid damage on automotive outer panels. From a practical point of view, dents can be caused in a number of ways. Considering doors as an example, denting can occur from stone impacts or from the careless opening of an adjacently parked vehicle door. Denting can occur where the door surface is smooth and may not have sufficient curvature to resist dent. These exterior body parts are designed to improve dent resistance using a combination of work hardening and bake hardening. In brief, dent is affected by the shape of the parts and the material properties such as yield strength, strain and thickness. In this work, forming of door outer panel is investigated by Taguchi method. Main parameters are yield strength, thickness, blank size, blank holding force and so on. For the given value of design parameters, forming analysis of the eighteen cases are carried out according to L18 orthogonal array. After comparing the performance by simple conversion of simulation results into dent resistance, the final suggestion of the forming parameters is verified for the optimal improvement of dent resistance.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2004년도 생명공학 실용화를 위한 비젼
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• pp.29-34
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• 2004

Reduction in stratospheric ozone layer increases the amount of ultraviolet-B radiation (UVB: 280-320 nm) that reaches the earth ’ s surface. UVB radiationcan damage plants, resulting in decrease in growth and productivity. UVB-augmentation studies have indicated that the sensitivity to UVB radiation in plants varies among the species and cultivars. However. there are no definitive answers for the mechanisms of UVB-resistance in higher plants and for bioengineering design and development of UVB-tolerant plants. We have been studying physiological and biochemical aspects of the effects of UVB radiation on growth and yield of rice COryza sativa LJ. aiming to clarify the mechanism of resistance to UVB radiationin rice. At this meeting. weintroduce our research as followed: (1) supplementary UVB radiation has inhibitory effects on the growth. yield and grain development of rice; (2) UVB sensitivity of rice varies widely among cultivars; (3) among Japanese rice cultivars. Sasanishiki. a leading variety in northeast Japan. is more resistant to UVB. while Norin 1. a progenitor of Sasanishiki. is less resistant; (4)UV-sensitive Norin 1 cultivar is deficient in photorepair of UVB-induced cyclobutane pyrimidine dimer (CPD). and this deficiency results from one amino acid residue alteration of CPD photolyase. These results suggest that spontaneously occurring mutation in CPD photolyase gene could lead to difference in UVB sensitivity in rice. and that CPD photolyase might be a useful target for improving UVB-sensitivity in rice by selective breeding or bioengineering of UVB-tolerant rice.

• 한국작물학회지
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• 제48권5호
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• pp.388-391
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• 2003

Tobacco mosaic virus (TMV), TMV-common strain, causes severe damage at growth, yield and leaf quality on flue-cured tobacco in Korea. Controlling TMV outbreak with cultivating practices and chemicals are limited, thus, the best way would be developing TMV resistant variety. A new flue-cured hybrid, KF118, was developed from a cross of maternal parent MSTC175 and TC853 at the Agro-tech. Research Group, KT＆G Central Research Institute. KF118 exhibited more vigorous growth characteristics in early stage than that of NC82, standard variety in Korea, while other characters were favorable to those of NC82, It is highly resistant to TMV and bacterial wilt(Ral-stonia solanacerum), and black shank(phytophthora parasitica var. nicotianae) is comparable to that of NC82. It should adapt well to the flue-cured production area, and can reduce premature flowering under unfavorable weather conditions. Yield of KF118 is 1 to 2% higher, and leaf quality is 4% higher than NC82. Fl hybrid, KF118, met acceptable standards for chemical and physical characteristics of cured leaf, and ranked high in good smoking taste by panel members in KT＆G.

• Journal of Plant Biology
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• 제39권4호
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• pp.309-314
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• 1996

Developmental of photosynthetic pigments and changes in chlorophyll fluorescence of dark-grown rice seedlings were studied during greening. Light-illumination stimulated accumulations of total chlorophylls and carotenoids in leaves of etiolated seedlings, accompanied by a decrease in the ratio of chlorophyll a to chlorophyll b. When the composition of carotenoids was analyzed, violaxanthin level was shown to increase up to 24 h after the beginning of light illumination, followed by a subsequent decline. In contrast to this, zeaxanthin level increased consistently with progress of deetiolatin. The role of zeaxanthin is discussed in relation to chlorophyll fluorescence quenching. A study on chlorophyll fluorescence kinetics of the rice seedlings being deetiolated showed a time-dependent increase in Fv/Fm (yield of variable fluorescence/maximum yield of fluoresecnece) ratios, indicating that greening is responsible for the activation of photochemical reaction centers of the photosystem. When chlorophyll fluorescence quenching was examined, qNP (nonphotochemical quenching) and qE (energy-dependent quenching) exhibited a time-dependent decline with progress of greening. The presented results indicate that greening-induced development of the photosynthetic machinery is associated the conversion of the carotenoid violaxanthin to zeaxanthin, suggesting that zeaxanthin synthesized in the illuminated leaves may provide the protection from the damage when etiolated plants are exposed to light.

• 한국안전학회지
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• 제38권2호
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• pp.44-51
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• 2023

With the recent increase in gas energy use, risk management for explosion accidents has been emphasized. Protective walls can be used to reduce damage from explosions. The KOSHA GUIDE D-65-2018 suggests the minimum thickness and height of protective walls, minimum reinforcement diameter, and maximum spacing of reinforcements for the structural safety of the protective walls. However, no related evidence has been presented. In this study, the blast load carrying capacity of the protective wall was analyzed by the pressure-impulse diagrams while changing the yield strength of the reinforcement, concrete compressive strength, reinforcement ratio, protective wall height, and thickness, to check the adequacy of the KOSHA GUIDE. Results show that failure may occur even with design based on the criteria presented by KOSHA GUIDE. In order to achieve structural safety of protective walls, additional criteria for minimum reinforcement yield strength and maximum height of protective wall are suggested for inclusion in KOSHA GUIDE. Moreover, the existing value for minimum reinforcement ratio and the thickness of the protective wall should be increased.

• 한국토양비료학회지
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• 제33권5호
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• pp.340-346
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• 2000

본 실험은 질소 시비 수준 0, 80, 160, $240kg\;ha^{-1}$에 따른 율무 1호 품종의 생육 특성, 조곡 수량, 질소축적 및 수확 후 토양의 화학성분 변화를 조사하였다. 질소시비 수준이 증가될수록 출수, 개화기는 단축되었으나 개화기부터 수확기까지 소요되는 기간은 증가되어 파종에서 수확기까지 소요되는 기간은 0-5 일 증가되었다. 질소시비 수준이 증가할수록 간장, 주분얼경의 수, 착립부위고는 유의한 증가를 보였다 (P<0.05). 주간절수, 주간직경, 착립부위장은 유의한 차이가 없었다. 주간의 소수지경수, 주간의 착립절간은 유의한 증가가 있었으나 $80kg\;ha^{-1}$ 이상에서는 큰 차이가 없었다 (P<0.05) 조명나방 피해는 질소 $240kg\;ha^{-1}$ 처리구에서 30%로 높아 수량감소의 요인으로 작용하였다. 수량구성요소는 질소시비량과 비례하여 양호해지는 경향이었으나 주당립수는 질소시비량 $160kg\;ha^{-1}$ 구에서 가장 많아 조곡 수량이 $3,410kg\;ha^{-1}$로 최고 질소 시비수준인 $240kg\;ha^{-1}$구에 비해 $140kg\;ha^{-1}$ 많았다. 질소사용효율은 질소시비량이 증가할수록 감소하였다. 실험후 토양중 총 질소함량은 실험전에 비해 질소 0, $80kg\;ha^{-1}$ 구에서는 낮았으며 질소 160, $240kg\;ha^{-1}$ 구에서는 높았다.

• 한국자원식물학회지
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• 제34권4호
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• pp.257-262
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• 2021

본 연구는 토양 내 콩씨스트선충(Heterodera glycines)의 초기 밀도에 따른 콩의 수량구성요소 및 수량에 미치는 영향을 규명하기 위하여 실시하였다. 재배포를 35개의 구역을 나누고 콩씨스트선충의 파종 전 토양 내 씨스트 밀도와 알 밀도를 조사하였으며, 수확기 콩의 초장, 협수, 립수, 백립중을 비교 분석하였다. 초기 씨스트의 밀도보다 씨스트 내 알의 밀도가 수량에 더욱 큰 영향을 미쳤으며, 초기 알 밀도가 높을수록협수와 수량이 초기 알 밀도가 높을수록 감소하는 경향을 보였고 토양 100 cm³ 당 알의 밀도가 2,000개 이상일 때부터 수량이 20% 이상 급격하게 감소하였다. 본 연구결과를 통하여 콩 재배 시 콩씨스트선충에 의한 피해를 예측할 수 있으며, 국내 콩 재배지의 약 40%가 감염되어 있는 콩씨스트선충에 대한 저항성 품종 육성을 포함한 다양한 방제방법 연구가 필요하다.