• Journal of Ecology and Environment
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• 제30권4호
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• pp.347-356
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• 2007

The structure and dynamics of Korean red pine stands established in the riparian zone were studied in the Tsang stream in Mt. Seorak National Park, in east-central Korea. Pine stands were classified into four successional stages, the initial, establishing, competitive, and stabilizing stages, based on the age distribution of a dominant tree, Pinus densiflora, the vegetation stratification, and the microtopography of the riverine environment. The stages usually corresponded to disturbance frequencies, depending on the horizontal and vertical distances from the watercourse. Stands of the initial and establishing stages lacked tree or subtree layers, or both. As stands progressed through the developmental stages, soil particle size became finer and moisture retention capacity was improved. The stand ordination reflected the developmental stage, and the species ordination differentiated species specializing in relatively dry and wet habitats. The results of the analysis of vegetation dynamics provided ecological information which will be useful for understanding the developmental processes of vegetation established in riparian zones. Species diversity indices usually increased across developmental stages, following the typical pattern for successional processes. We discuss the importance and necessity of riparian vegetation in Korea, where most riparian forests have disappeared due to excessive human land use.

• 셀메드
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• 제1권1호
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• pp.4.1-4.4
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• 2011

Excessive stress is harmful to academic performance in children and may lead to dropping out of school. To meet the demands of a modern life-style which is full of speed, stress and tension, an all-round child health program is crucial. The use of yoga for children has diverse applications in maintaining and developing their physical, mental, intellectual, emotional and spiritual levels. Yoga, through its physical postures (asana), breathing practices (pranayama), cleansing techniques (kriya), meditation therapies (dhyana) and relaxation training (yoga nidra) yields a positive effect in the management of stress in children. Yoga practice benefited children by improving their eye-hand coordination, attention span, levels of concentration, competitive performance and relaxation. Visually impaired children showed a significant decrease in their abnormal anxiety levels when they practiced yoga for three weeks, while a program of physical activity had no such effect. Socially disadvantaged children in a remand home showed significant improvements in sleep, appetite and general well being, as well as a decrease in physiological arousal after yoga. In one study, it is found that a 4-week program of asana and meditation lowers the aggressive behavior of children. Meditation helped to reduce problems related to maladaptive behavior, increase emotional and physical health and psychological well-being in children. Finally, the possible role of yoga in improving the mental state and general well-being of children with cancer is being explored.

• 한국수소및신에너지학회논문집
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• 제2권1호
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• pp.15-21
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• 1990

Nickel-hydrogen battery systems with metal hydride alloys are expected to have both higher energy density and lower pollution than nickel-cadmium cells. Nickel-hydrogen storage cells are expected to be well-suited for use in space crafts for a large capacity power storage system. Their major advantages are not only a capability of deep DOD(depth of discharge) using but also with excellent durability under excessive overcharging and overdischarging. In this study, the charge/discharge capacities, anodic polarization characteristics and durability for the continious charge/diacharge cycling of the $Ti_{1-X}Zr_XVNi$ and $Ti_{1-X}Zr_XV_{0.5}Ni_{1.5}$ alloys were measured by electrochemical method. The electrode properties of the copper or nickel plated $Ti_{1-X}Zr_XV_{0.5}Ni_{1.5}$ alloys were examined with a battery charge/discharge testing system in the temperature range of -5 to $25^{\circ}C$.

• 한국건설관리학회논문집
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• 제4권4호
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• pp.88-95
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• 2003

탈수거푸집공법은 거푸집 표면에 잉여수를 배출시킬 수 있는 구멍을 뚫고 내측에 섬유포를 부착하여 콘크리트 타설시 잉여수 및 혼입공기를 배출시키는 공법으로 시공상의 워커빌리티를 확보하면서 콘크리트 표층부 품질을 강화시킬 수 있다. 따라서 제치장 콘크리트 표면의 강도를 극대화할 뿐만 아니라, 수밀한 콘크리트 표층부를 생성하기 때문에 물이나 공기, 염분 등이 침투하기 어려워 콘크리트의 내구성을 크게 향상시킬 수 있다. 그러나 현재 국내에서는 이론적으로는 제기되고 있으나, 관련규준 및 시공방법에 대한 연구가 부재해 공사현장에서 적용할 기회가 없는 실정이다. 이에 본 연구에서는 물성실험을 통해 탈수거푸집 설계를 위한 기초자료를 제공하고, 이를 바탕으로 한 현장적용실험을 통해 탈수거푸집공법의 실용화 방안을 제안하고자 한다.

• 복식
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• 제56권1호
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• pp.106-120
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• 2006

Using aesthetics of Rosencranz as the basis, this study contains the peculiarities of 'ugliness' and the obscured conceptual meaning of 'avant-garde', 'grotesque', and 'decadence' that are being utilized under ambiguous significance are defined through modern fashion and fashion of online game characters. Forms of 'ugliness' expressed in modern fashion and in games characters display distortion of form through incongruity, unbalance, disproportion and disharmony, and with this lack of form and expressional imprecision, both contain the elements of comical characteristics of vulgarity and repugnance. The difference in 'ugliness' between modern fashion and game character fashion is, the significance of 'ugliness' being expressed in modern fashion challenges new concepts by refusing tradition and recovering the human nature that has become turbid. On the other hand, 'ugliness' in game character fashion complements the story of the game that uses legends, fantasies or novels as its basis. Opposed to the significance of recovering human nature that is displayed in modern fashion, in order to terminate the opposing game character, the fashion of game characters exaggerates the form of modern fashion with added brutality. In addition, with the advantage of virtual reality that allows a more flexible expression than in the real word, images created are more sensational and excessive use of grotesque images are being expressed.

• 대한기계학회논문집A
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• 제29권5호
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• pp.689-697
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• 2005

This paper presents the reliability estimation of door hinge for home appliances, which consists of bushing and shaft. The predominant failure mechanism of bushing made of polyoxymethylene(POM) is brittle fracture due to decrease of strength caused by voids existing, and that of shaft made of acrylonitrile-butadiene-styrene(ABS) is creep due to plastic deformation caused by excessive temperature and lowering of glass transition temperature by absorbed moisture. Since the brittle fracture of bushing is overstress failure mechanism, the load-strength interference model is used to estimate the failure rate of it along with failure analysis. By the way, the creep of shaft is wearout failure mechanism, and an accelerated life test is then planned and implemented to estimate its lifetime. Through the technical review about failure mechanism, temperature and humidity are selected as accelerating variables. Assuming Weibull lifetime distribution and Eyring model, the life-stress relationship and acceleration factor, $B_{10}$ life and its lower bound with $90\%$ confidence at worst case use condition are estimated by analyzing the accelerated life test data.

• 패션비즈니스
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• 제8권1호
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• pp.107-116
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• 2004

In the modern society, magazine is a information communicating media which is an important element in assessing the whole of a nation's cultural standard. More subdivided fields of magazines are expanding according to the diversified concepts. As the variety of Korean edition of foreign magazines are increasing, the type of Women's magazines are also diversifying and expanding. By finding out the problems and analyzing the visual side of domestic women's magazines among the intense competition of the magazines, the design improvement program was requested. The analysis result from the visual side of domestic women's magazines tells us that the problem of current domestic women's magazines is that their identities are not clear. The cause can be divided into three reasons: First, it is the lack of creativity and originality. There is a limitation in arousing the readers' interests by designing the magazines with similar layouts. Second, there are no distinct design concepts in the magazines. It seems as if the uniformity is lacked as the impression the magazine gives is not clear. The diversification of layouts and the use of design elements could actually bring about a counter result. Third, the excessive advertisement pages is another reason. The ads that covers over 35% of the whole of the magazine can act as a factor that drops the readers' trust in the magazine.

• 한국정밀공학회지
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• 제32권8호
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• pp.681-685
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• 2015

Hastelloy C-276 composed of Cr, Mo, and Ni is a versatile, corrosion-resistant alloy with numerous industrial applications including its use in nuclear reactors, general chemical plants, and as a superconducting base material. Of especial significance, it can be used as a thin-sheet type whereby lap-joint welding is occasionally necessary. The main welding problems for thin-sheet metals are deformation and burn-through from an excessive heat input. Laser welding can minimize these problems because it has a high energy density and low heat effect on the base material. In this study, the laser-welding characteristics of lap-joint Hastelloy C-276 sheet metal were determined. The criteria of the laser-welding variables were chosen using a heat-conduction analysis, and the optimal welding parameters were selected by experimenting with an Nd:YAG laser.

• 한국운동역학회지
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• 제22권2호
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• pp.237-242
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• 2012

The purpose of this study was (a) to develop carbon nanotube-based shock absorbers for reducing potentially harmful impact forces and excessive foot pronation, and (b) to briefly determine how the effects of carbon nanotube-based shock absorbers on biomechanical variance during drop landing. A university student(age: 24.0 yrs, height: 176.2 cm, weight: 679.5 N) who has no musculoskeletal disorder was recruited as the subject. Hardness, specific gravity, tensile strength, elongation, 100% modulus, tear strength, split tear strength, compression set, resilience, vertical GRF, and loading rate were determined for each material. For each dependent variable, a descriptive statistics was used for different conditions. The property test results showed that tensile strength, tear strength, split tear strength, compression set, and resilience in carbon nanotube-based shock absorbers were greater than general Ethylene Vinyl Acetate(EVA). These indicated that resistance against variable strength in developed carbon nanotube-based shock absorbers were greater than general EVA. In vertical GRF of CNTC was less than those of EVA during drop landing and loading rate of CNTC was greater than EVA. It seems that the use of CNT can be a effective way of reducing and controlling shock from impact.

• Journal of Welding and Joining
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• 제33권2호
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• pp.23-31
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• 2015

Stainless steel is used in automobile muffler and exhaust systems. However, in comparison with other steels it has a high thermal expansion rate and low thermal conductivity, and undergoes excessive thermal deformation after welding. To address this problem, we evaluated the use of arc brazing in place of welding for the processing of an exhaust system, and investigated the parameters that affect the joint characteristics. Muffler parts STS439 and hot-dipped Al coated steel were used as test specimens, and CuAl brazing wire was used as the filler metal for the cold metal transfer (CMT) welding machine, which is a low heat input arc welder. In addition, a Box-Behnken design of experiment was used, which is a response surface methodology. The main process parameters (current, speed, and torch angle) were used to determine the appropriate welding quality and the mechanical properties of the brazing part was evaluated at the optimal welding condition. The optimal processing condition for arc brazing was 135A current, 51cm/min speed and $74^{\circ}$ torch angle. The process was applied to an actual exhaust system muffler and the prototype was validated by thermal fatigue, thermal shock, and endurance limit tests.