• 한국정밀공학회지
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• 제21권4호
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• pp.39-47
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• 2004

In mold machining, there are many concave machining regions where chatter and tool deflection occur since MRR(material removal rate) increases as curvature increases even though cutting speed and depth of cut are constant. Boolean operation between stock and tool model is widely used to compute MRR in NC milling simulation. In finish cutting, the side step is reduced to about 0.3mm and tool path length is sometimes over loom, so Boolean operation takes long computation time and includes much error if the resolution of stock and tool model is larger than the side step. In this paper, curvature of CL (cutter location) surface and side step of tool path is used to compute the feedrate for constant MRR machining. The data structure of CL surface is Z-map generated from NC tool path. The algorithm to get local curvature from discrete data was developed and applied to compute local curvature of CL surface. The side step of tool path was computed by point density map which includes cutter location point density at each grid element. The feedrate computed from curvature and side step is inserted to new tool path to regulate MRR. The resultants were applied to feedrate optimization system which generates new tool path with feedrate from NC codes for finish cutting. The system was applied to the machining of speaker and cellular phone mold. The finishing time was reduced to 12.6%, tool wear was reduced from 2mm to 1.1mm and chatter marks and over cut on corner were reduced, compared to the machining by constant feedrate. The machining time was shorter to 17% and surface quality and tool was also better than the conventional federate regulation using curvature of the tool path.

• 펄프종이기술
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• 제42권5호
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• pp.31-36
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• 2010

When corrugated board is folded at the severely low humidity condition, crack can occur along the scored (or creased) lines of linerboard. This phenomenon is called as score (or crease) crack. It is mainly resulted from the excessive concentration of stress on the outer layer of linerboard. To overcome score crack, many approaches including the installation of constant temperature and humidity system, displacement of low grade raw material by long and strong fibers, or application of water have been tried. We examined the effect of the weight fraction of top layer in two-ply sheet, freeness of top layer stock and wet pressing on strain and elastic modulus of sheet to prevent score crack. Lower freeness and higher press load increased the density and elastic modulus of sheet. Pressing load over the $50kgf/cm^2$, however, decreased the strain of sheet. The weight fraction of top layer had positive effect on strain as well as elastic modulus without increasing the density of sheet.

• 한국수산과학회지
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• 제42권6호
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• pp.695-702
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• 2009

This study includes spatial variations in the catch of billfishes in the Pacific Ocean and examines factors affecting interannual changes in the catch. Main billfish species caught by Korean tuna longline fishery were blue marlin and swordfish. A main fishing ground of the species was the tropical Pacific Ocean, while additional fishing ground of billfishes tended to be formed in the Pacific coast of Mexico in the El Nino periods. Further, the catch of billfishes was significantly related to CPUE (tons/average of the used hooks/vessel) in the entire Pacific Ocean as an index of stock abundance and equatorial SOI (EQSOI) as an index of El Nino event. Annual changes in the catch of billfishes in the Pacific Ocean could be regulated mainly by variations of stock abundance. In addition, increase of the density of billfishes in the tropical Pacific and additional formation of fishing ground by El Nino event possibly contribute to increase of the catch of billfishes in the Pacific Ocean. On the other hand, linear regression model may be more adequate in the analysis of relationships between fisheries data and indices made from using some environmental factors.

• Management Science and Financial Engineering
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• 제21권2호
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• pp.13-23
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• 2015

This study addresses the question as to whether the option prices have useful predictive information on the direction of stock markets by investigating a forecasting power of volatility curvatures and skewness premiums implicit in S&P 500 index option prices traded in Chicago Board Options Exchange. We begin by estimating implied volatility functions and risk neutral price densities every minute based on non-parametric method and then calculate volatility curvature and skewness premium using them. The rationale is that high volatility curvature or high skewness premium often leads to strong bullish sentiment among market participants. We found that the rate of return on the signal following trading strategy was significantly higher than that on the intraday buy-and-hold strategy, which indicates that the S&P500 index option prices have a strong forecasting power on the direction of stock index market. Another major finding is that the information contents of S&P 500 index option prices disappear within one minute, and so one minute-delayed signal following trading strategy would not lead to any excess return compared to a simple buy-and-hold strategy.

• Journal of Ginseng Research
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• 제7권2호
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• pp.156-162
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• 1983

Stability of nitrogen compounds in the water-extract of ginseng has been investigated in terms of concentration and SDS-PAGE protein pattern as functions of times and temperature. The concentration of free amino-nitrogen in the extract of fresh ginseng varied with time at various temperatures. Especially at temperature over 90$^{\circ}C$, it showed a tendency of steady declease at a considerably fast rate. In the case of red ginseng which had been commercially processed and stocked for 1-7 years, it was found that the free amino-N concentration diminished gradually depending on the length of stock period of samples. This result may be comparative to another observation that the amount and density distribution of precipitate from extract varied with the lapse of stock time, based on accelerated sedimentation test. The number of SDS-PAGE protein bands was observed to be at least seven when determined with the extract of fresh ginseng. However, it tended to reduce finally to be one band when the extract was kept at a rather high temperature for a long time.

• 한국수산과학회지
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• 제53권4호
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• pp.563-565
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• 2020

Turbot Scophthalmus maximus can be cultured at a higher density and has a faster growth rate than olive flounder Paralichthys olivaceus, making it an attractive alternative for flounder farmers in Korea. As it is a relatively new species to Korean farming environments, there is no general farming protocol, which takes multiple generations to develop, for turbot in Korea. Nevertheless, we applied breeding technology to develop a stock, which we considered first-generation turbot. Then we compared its growth rate (an important economic trait) to different populations (the original stock of Korean turbot, French turbot, and Chinese turbot). The four different populations were grown in similar culture conditions. First-generation Korean turbots grew about 28% faster than all others. We will continue to select for important traits such as color, disease resistance, and heat tolerance in this turbot broodstock; we believe that with the appropriate selection process, Korean turbot should become competitive in the markets, and will become a major farming species in the Korean aquaculture industry.

• 현장농수산연구지
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• 제16권1호
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• pp.143-154
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• 2014

Settlement of artificially released abalone, Haliotis discus hannai at the marine farming area in Jeollanam-do in 2007 was very efficient by showing the recapture of 2.0-5.2 ind./m² and the survival rate of 60-67%. The growth of shell after 1 year was highest in Hwoenggando by 75.9 mm and the lowest in Hwasan by 64.6 mm. Our result especially showed that the effect of the stock recruitment was the most efficient when abalone was released. The shell growth of the released abalone was better when sea mustard (Undaria sp.) was provided as food (shell length was up to 23.9 mm) or predators were periodically removed (shell length was up to 23.8 mm) in order to enhance the effect of the artificial release than the control group. The recapture rate was also higher than the control. However due to the difficulty of managing the release areas, it will be more efficient to release the recruited stocks after considering various biological and ecological factors such as survey of suitable release areas, stock size, release density, and health of stocks.

• 미생물학회지
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• 제52권1호
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• pp.120-124
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• 2016

P2-크기 머리에 packaging 될 특정 DAN 크기(28-29 kb long)와 박테리오파지 P4 유전자 sid의 변이가 "P2 sir-관련 도움파지 비효율성"을 극복할 수 있는 요소로 압축되었다. 유전자 sid의 변이 여부가 필수적인지를 확인하기 위해, 정상적인 sid 유전자를 가지며 $P2_{sir3}$-크기의 큰 머리에 packaging 될 DNA 크기가 28.5 kb되는 P4 delRI::kmr을 사용하여 실험하였다. P4 delRI::kmr이 P2 sir3 용원소에 대해 낮은 EOP를 보이므로, 이를 증가시키기 위해 P2 sir3 용원소를 숙주세포로 하여 파지 stock을 제조하였다. 이 과정에서 P4 delRI::kmr이 P2 sir3 용원소에 대해 적응하는 것을 관찰하고, CsCl 부양 균등밀도 편차실험과 분리된 DNA의 전기영동을 통해 그것이 packaging 될 머리 크기에 따른 DNA 형태 변화에 의한 적응이라는 것을 알아냈다. P2 sir3 용원소에 적응된 P4 delRI::kmr과 적응되지 않은 P4 delRI::kmr stock의 burst size 결정 실험은, sid 유전자 변이에 상관없이 packaging 될 DNA 크기에 의해 "P2 sir-관련 도움파지 비효율성"이 극복된다는 것을 보여주었다.

• 한국화재소방학회논문지
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• 제21권4호
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• pp.52-58
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• 2007

본 연구는 숲 가꾸기 실행지와 미실행지의 임분 특성이 산불에 미치는 영향에 관한 연구이다. 조사지역은 강원도 양양군, 인제군 그리고 경기도 가평군 등 3개 군에서 14개소를 선정하였으며, 이중 숲 가꾸기 실행지 9개소, 미실행지의 5개소에 대한 현장조사를 실시하였다. 현장조사를 통해 임목의 수고, 흉고직경, 지하고, 죽은 가지 고사율, 임목밀도, 울폐도, 관목층 및 초본층 피도를 조사하였으며 이 자료를 통해 숲 가꾸기 실행 및 미실행지의 임내특성분석을 실시하였다. 또한 임내특성 분석으로부터 산불발생 및 확산 위험성과의 관계를 분석하였다. 숲 가꾸기 실행지역과 미실행지역의 임분 특성조사 결과 숲 가꾸기 실행지역이 미실행지역에 비해 상대적으로 평균 지하고는 높았고, 임목본수는 적었으며, 죽은 가지 고사율은 적었고, 초본층 피도는 높게 나타나고 있어 숲 가꾸기 실행지역의 산불위험도는 미실행지역보다 낮아질 것으로 판단되었다.

• 한국철도학회논문집
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• 제14권4호
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• pp.333-340
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• 2011

본 논문은 유럽 TSI와 국내철도차량안전기준에 정의된 건널목 충돌사고시나리오에서 요구하는 성능의 대형 변형체 장애물의 유한요소 모델에 대하여 2가지 종류의 모델을 개발하여 한국형 분산형 고속철도 차량에 적용하고 평가하였다. 규정에서 요구하는 대형 장애물은 기존 강체모델에서 현재의 변형체모델로 변경되었으며 규정에 정의된 방법으로 변형체 강성 값이 검증되어야 한다. 여러 번의 시뮬레이션을 통해 기준을 만족하는 균일한 밀도와 강성의 솔리드 형 장애물 모델과 균일하지 않은 셸 형 장애물 모델 등 2가지를 개발하였다. 본 연구에서 개발된 대형장애물을 사용하여 분산형 고속열차를 대상으로 규정의 대형장애물 충돌시뮬레이션을 수행하였고 그 결과를 평가하였다. 셸 형과 솔리드 형 장애물은 열차와 충돌 후 거동에 상당한 차이가 있었고, 셸 모델이 더 가혹한 결과를 나타내었다.