• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.246-248
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• 2002

This paper presents computer simulations of the stacking and transfer system for the fast freeform fabrication system. The stacking and transfer system is essential for the fast freeform fabrication system and its stable motion is very important fer the consistent stacking of the cut slices. The stacking and transfer system cane be modeled as a pneumatic system. The system consists of air compressor, the control valve, and the cylinder. The governing parameters have been changed and the simulation results are shown to predict the time response of the system. The results shows some parameters should be correctly tuned to obtain stable system response.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.937-940
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• 2010

본 연구는 fine blanking 프레스로부터 기능면으로 사용되는 100% clean cut 전단면을 얻는 fine blanking 공정에서 die roll을 최소화하기 위한 목적으로 성형 해석 및 실험적 방법을 통해 die chamfer 형상에 따라 성형되는 제품의 die roll size 변화를 검토한 것이다. fine blanking 과정을 묘사하기 위하여 deform 2D를 이용하여 성형 해석을 수행하여 die roll size를 예측하였으며, 실제 die chamfer가 다른 die insert를 제작하여 fine blanking 실험을 실시하여 die chamfer 형상에 따른 die roll size에 대한 해석 data와 실험 data를 비교 분석하여 die roll 길이 방향 size의 경향을 파악할 수 있었다. 이 연구 결과는 fine blanking 판재 성형에서 die roll을 최소화하기 위한 die chamfer 설계에 유용하게 적용될 것으로 판단된다.

• Journal of the Korean Society of Safety
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• v.35 no.4
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• pp.40-47
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• 2020

Although gangform has good workability due to the integration of outer wall forms and working platforms, 22 workers were died from 21 gangform related accidents during 2012 to 2016. Quantitative risk assessment is required for evident based prevention measure selection. In this study, based on 52 accident data from 2004 to the first half of 2019, FTA is conducted for probabilities of direct causes and their contribution to accidents. Three stages are considered; gangform installation, dismantling and lifting, and using. The effectiveness of countermeasures is evaluated through minimum cut set, RAW and RRW. Complete assembly of gangform on the ground level, detailed planning, and fall prevention device are suggested as prevention measures for installation, dismantling and lifting, and using stages, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.490-495
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• 2001

This paper deals with an analysis and countermeasure for improving the shock performance of laptop computers. The shock analysis is carried out by using the commercial program of LS-DYNA3D. Also the analysis is verified by the measurements from modal tests and shock tests. The available countermeasures are investigated theoretically and experimentally to find the effective methods of reducing the shock acceleration on hard disk driver during one side fall test. The hard disk drive is the most sensitive part in a laptop computer. This research shows the effects of the spring constant of rubber pad, the reinforcement of mechanical parts and the location of a hard disk driver, on the shock reduction.

• Korean Journal of Plant Resources
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• v.11 no.3
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• pp.326-334
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• 1998

Vascular cambium in 16 species of Salicaceae is nonstoried in all of them and is made up of fusiform and ray initials. The growth of cambial girth occurred by pseudotransverse division of fusiform initials and subsequent apical intrusive growth of daughter initials. The measurements of fusiform initials in tangerntial sections have revealed that the average length varies from 252.2-437.1${\mu}{\textrm}{m}$ in investigated species, with the maximum being in Populus euramericana and the minimum in Salix purprea var. Multinervis. The length of fusiform initials depends on the length of the tapering end wall , therefore, the longer the length of the tapering end wall, therefore, the longer the length of the taperding end wall, the longer the length of fusiform initials. Ray initials have their own size, magnitude, and frequency of occrrence in each species. The relative proportion of ray initials fall about 15.0-24.5% in Salicaceae. Shrubby species of Salix have a lower ratio of ray initials than the species which possess wider trunks. New ray initials are originated from cut off the side or the end of fusiform initials and central partition of a fusiform initials.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.334-335
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• 2021

In this paper, the distance traveled by a vehicle in an area where a part of the road is cut is measured using the motion of a parabola. Here, when a car running at a constant speed passes over the edge of a broken road, how far it goes from the edge of the road to fall was calculated.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.8 no.1
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• pp.91-97
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• 1970

It is one of the important subjects in fall crop production of potatoes in korea to find the proper direct planting method as a substitute for transplanting method by sprouting inducement at seed-bed. From this point the author has undertaken this experiments to examine the effects of several handling methods of seed tuber pieces at planting on sprouting of fall grown potatoes at Ansung Agricultural College from August to september in 1969. The results of experiments induced sprouting with Gibberellin treatment using the variety Irish Cobbler were as follows; 1. Sun light exposure treatment to cut surface of potato seed pieces resulted in rotting of seed pieces and delay of sprouting and bud growth. Exposure more than three hours induced severe rotting(more than fifty percent) of seed pieces (Table I). 2. When soil moisture are abundant and the duration of sun light. exposure is short, even direct planting method of treated seed pieces with Gibberellin resulted in good potato stands (Table 2). 3. The direct planting method, as the rotting of seed pieces are avoidable are applicable in fall crop production of potatoes us a substitute for transplanting method because the sprouting and bud growth are promoted more in case of direct planting than transplanting (Table 3). 4. When the humidity in the bottle was low no healing effects was found by holding the seed pieces in large closed bottle under the trees for three days before planting (Table 2). 5. If duration of sunlight exposure is short, no difference of potato stands between clear day planting and cloudy day plant ing (Table 3). 6. As long as soil moisture deficiency. was not induced the irrigation at planting shows no effects to protect the seed piece rotting after planting (Table 3).

• Journal of the Korean association of regional geographers
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• v.7 no.2
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• pp.71-81
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• 2001

According to the change of stream power/resisting power relationship due to the crustal movement or the climatic change, most channel landforms which reflect the equilibrium state of fluvial system are eroded and a part of them is remained as a river terrace. In many rivers in Korea are extensively distributed the relatively younger low river terraces. But their accurate formation mechanism is not known. In this paper, the formation processes and the dating of low river terraces distributed in Nakdong River basin will be investigated. Stream power of the downward erosion was revived because the sea level fell down. So stream power was superior to the resisting power under the cool-wet climatic condition during the last glacial period. Thus the river bed was excavated deeply, so that low river terraces were built up. And many incised meander loops were cut during this period. But, when fluvial system did not have equilibrium over all reaches, the last glacial period ended and the sea level initiated to rise rapidly. The headward erosion from the fall of sea level during the last glacial period had kept up to Hagye Fall because of the cutting of incised meander loops. Deeply excavated valleys and abandoned channel of cut-meander in lower reaches of a stream were filled with sediments. Thus the longitudinal profile of the uppermost reaches reflect the last interglacial, the upper reaches the last glacial, and the middle/1ower reaches recent fluvial system. Therefore low river terraces have been formed since the last glacial period.

• Journal of Ecology and Environment
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• v.41 no.3
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• pp.66-71
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• 2017

Background: The sprouts of oak species play an important role in maintaining the oak community in a disturbed environment. In this study, we cut 1-year-old oak in three times during the 3 years and measured the sprout responses to know sprouting ability of six deciduous oaks in Korea. Results: Oak sprouts have appeared in spring and fall, and some of the sprouts had lifespan as short as a month. As the number of cutting increases, sprout number of Quercus acutissima increased whereas the other oak species decreased or died. The average number of sprouts over the 3 years was from 1.4 (Quercus mongolica) to 2.2 (Q. acutissima) per individual. Quercus serrata died after the second cutting, and Quercus dentata died after the third cutting. So, the two species have the lowest sprouting ability among six oak species. The sprouts grew actively during fall and slowly in summer. The sprout length during the 3 years was in the following descending order: Q. acutissima, Quercus aliena, Q. dentata, and Q. mongolica. Sprout of Q. acutissima and Q. aliena generated steadily over the 3 years, and sprout of Quercus variabilis and Q. mongolica was changed by year. After the 3 years, the number of sprouts increased only in Q. acutissima but sprout number of the other five oak species decreased. The sprout length of Q. acutissima, Q. aliena, and Q. variabilis increased, but sprout length of the other three oak species decreased. The average survival rate of saplings over the 3 years was in the following descending order: Q. acutissima, Q. aliena, Q. variabilis, and Q. mongolica. Conclusions: As a result, the sprouting ability of Q. acutissima was the highest. Such level of sprouting ability may be the evidence of how Q. acutissima community exists as a dominant species in a disturbed environment in lowlands of Korea peninsula.

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.89-98
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• 2009

Existence of core stone at the inside of the Rock mass is reacting as unstable element. In particular, in case of the cut slope, even when it is not exposed, slope's discontinuity increases or strength level decreases depending on the difference in the weathering grade when it comes to the core stone, and reacts as an important element of the slope movement such as slope's rock fall or collapse. As for the slope that is subject to study, incision was completed after 20 years or so, and parts of the slope reinforcement was completed, but frequent rock fall occurs despite small amount of rainfall, and permanent stability measures are urgent. Refractional seismic survey and geological survey results were compared and analyzed, and reliability was improved by complementing the two survey methods, and stereo-graphic projection using DIPS program was conducted to analyze the characteristics of oore stone in the weathered soil slope.