• 한국건축시공학회지
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• 제6권4호
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• pp.45-52
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• 2006

Top Down method is more widely used in downtown construction, recently. As underground construction constitutes a significant portion of the total construction cost and time in Top Down construction, it is important to develop a construction method to reduce the time required in underground works. The purpose of this study is to analyze load carrying capacity of Top Down prefounded columns on different excavation schedule. When several floors are excavated, the valid buckling length of prefounded column is increased and allowable buckling stress is decreased. The result shows that all columns are safe in buckling down to B3 story whether 2 or 3 stories are excavated. However, several columns are not safe from B4 story when 2 or 3 stories are excavated straightly. With these results, a process can be designed that the first three stories in the basement are excavated, and then excavate B4 story after placing concrete on B1 and B2 floor.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.854-859
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• 2018

Calculating minimal cut sets is a typical quantification method used to evaluate the top event probability for a fault tree. If minimal cut sets cannot be calculated or if the accuracy of the quantification result is in doubt, the Monte Carlo method can provide an alternative for fault tree quantification. The Monte Carlo method for fault tree quantification tends to take a long time because it repeats the calculation for a large number of samples. Herein, proposal is made to improve the quantification algorithm of a fault tree with circular logic. We developed a top-down iteration algorithm that combines the characteristics of the top-down approach and the iteration approach, thereby reducing the computation time of the Monte Carlo method.

• Wind and Structures
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• 제17권5호
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• pp.465-477
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• 2013

In this paper, the effects of parapets on the mean and fluctuating wind pressures which are acting on a flat top of a finite cylinder vertically placed on a flat plate have experimentally been investigated. The aspect ratio (AR) of cylinder is 1 and the Reynolds number (Re) based on cylinder diameter and free stream velocity is 150000. The pressure distributions on the flat top and the side wall of the finite cylinder immersed in a simulated atmospheric boundary layer have been obtained for different parapet heights. The large magnitudes of mean and minimum suction pressures occurring near the leading edge were measured for the cases with and without parapet. They shift to the further downstream on the circular top with increasing parapet height. It is seen that the parapets reduce the local high suction on the top up to 24%.

• Advances in materials Research
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• 제7권3호
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• pp.185-194
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• 2018

The mechanism of biological materials structure is very complex and has optimal properties compared to engineering materials. Top Neck mollusks shells, as an example of biological materials, have hierarchical structure, which 95 percent of its structure is Aragonite and 5 percent organic materials. This article detected mechanical properties of the Top Neck mollusks shell as a Nano composite using Nano-indentation method in different situations. Research findings indicate that mechanical properties of the Top Neck mollusks shell including elastic modulus and hardness are higher than a fresh one preserved in -50 centigrade and also a Top Neck mollusks shell preserved in environmental conditions. Nano-indentation test results are so close in range, overall, that hardness degree is 3900 to 5200 MPa and elastic modulus is 70 to 85 GPa.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.180.1-180.1
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• 2003

Eukaryotic DNA topoisomerase I (top I) is an essential enzyme that act to relax supercoiled DNA during the transcription, replication and mitosis. Intracellular levels of top I are elevated in a number of human solid tumors, relative to the respective normal tissues, suggesting that controlling the topI level is important to treat cancer. Top I poisons show their antitumor activities by stabilizing the cleavable ternary complex consisting of top I enzyme, DNA, and drug. Thus, top I is a promising target for the development of new cancer chemotherapeutics against a number of solid tumors. (omitted)

• 한국지반환경공학회 논문집
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• 제18권2호
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• pp.5-19
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• 2017

국내 건축물 시공을 위한 지하 굴착은 안정성, 경제성 및 굴착 주변 여건 등을 고려하여 재래식 버팀대 공법(Strut, Ground Anchor)에서 점차 Top-Down 공법을 개량한 내부 영구 지지체 공법으로 변화하고 있다. 본 연구에서는 국내에서 범용적으로 사용되고 Top-Down 공법, New Top-Down 공법, S.P.S 공법, S.T.D 공법 및 B.R.D 공법 등 내부 영구 지지체 공법 현장을 선정하여 재래식 버팀대 공법과 공사비 및 공기를 비교 분석하였다. 또한 공사 중 흙막이 벽체의 계측 자료를 분석하여 흙막이 벽체의 안정성을 확인하였다. 그 결과 깊은 굴착 및 기반암층이 지표면으로부터 가까운 경우 영구 지지체 공법이 재래식 버팀대 공법보다 경제성과 시공성이 우수함을 알 수 있었다

• 한국운동역학회지
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• 제15권1호
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• pp.221-235
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• 2005

The purpose of this study was to analyse badminton players' drop-shots, in order' to make players understand the principles of drop-shot motion in badminton. Three dimensional analysis was used to measure movements such as the time required per section, the change of center of gravity, joint angle and speed, and joint speed. The results of this study revealed as follows: (1) top players are faster than amateurs in the total time required per section; (2) top players moved more in the x-axis and z-axis, while amateurs moved more in the y-axis; (3) the inclination of amateurs was greater than that of top players in all phases; (4) amateurs showed larger angle on the shoulder joints than top players in the first phase, while top players showed larger angle on the shoulder joint than amateurs in the second and third phase. Amateurs' angle was larger on angle joint in the first phase than top players' ones, while top players' angle was larger in the third phase than amateurs; (5) the speed of racket head of top players was faster than that of amateurs; and the velocity of the center of gravity of amateurs was greater than that of the top players. The findings of this study were that gravity decreases during impact and then the velocity increases to perform the follow-through and making the swing fast by increasing the speed of the racket head is most important.

• 대기
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• 제24권1호
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• pp.39-48
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• 2014

This study provides a comparative analysis of cloud top heights observed by a Ka-band cloud radar and the Communication, Ocean and Meteorological Satellite (COMS) at Boseong National Center for Intensive Observation of severe weather (NCIO) from May 25, 2013 (1600 UTC) to May 27. The rainfall duration is defined as the period of rainfall from start to finish, and the no rainfall duration is defined as the period other than the rainfall duration. As a result of the comparative analysis, the cloud top heights observed by the cloud radar have been estimated to be lower than that observed by the COMS for the rainfall duration due to the signal attenuation caused by raindrops. The stronger rainfall intensity gets, the more the difference grows. On the other hand, the cloud top heights observed by the cloud radar have been relatively similar to that observed by the COMS for the no rainfall duration. In this case, the cloud radar can effectively detect cloud top heights within the range of its observation. The COMS indicates the cloud top heights lower than the actual ones due to the upper thin clouds under the influence of ground surface temperature. As a result, the cloud radar can be useful in detecting cloud top heights when there are no precipitation events. The COMS data can be used to correct the cloud top heights when the radar gets beyond the valid range of observation or there are precipitation events.

• 한국작물학회지
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• 제47권3호
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• pp.143-146
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• 2002

조기재배 고구마에서 2모작 재배용 묘를 생산하기 위하여 조기재배의 수량감소를 최소화하고, 2모작용 묘를 최대 생산하기 위한 최적 지상부 경엽절제에 대한 시험 결과는 다음과 같았다. 1. 무절제와 비교한 지상부 및 지하부의 생체중과 건물중은 15% 경엽절제 이하에서 수확기에 동일수준이었다. 2. 경엽절제 정도가 많아짐에 따라 지상부 경엽중의 감소는 주만장과 주만절수의 감소가 원인이었다. 3. 총저중이 20% 경엽절제까지 같은 수준이었던 것에 대하여 50g 이상의 상저중은 15% 경엽절제까지 무절제와 비교하여 동일 수준이었던 것은 경엽절제 정도가 많아짐에 따라 50g 이하의 설저의 증가로 상품화율이 감소했기 때문이었다.

• 한국시뮬레이션학회논문지
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• 제24권4호
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• pp.153-161
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• 2015

Top-k 위치정보서비스는 사용자의 위치로부터 가장 가까운 k개의 장소를 반환하는 서비스이다. 기존의 방법들은 사용자의 위치 정보가 LBS Server에 그대로 노출되어 사용자의 프라이버시 훼손의 문제가 있다. 본 논문에서는 완전동형암호를 사용하여 Top-k 위치정보서비스 사용자의 프라이버시를 보호하는 방안을 연구한다. 제안 방법에서는 사용자의 위치 정보가 포함된 질의와 Database의 위치 데이터 정보를 암호화한다. LBS Server는 완전동형암호를 이용해 암호화된 질의 위치 정보와 암호화된 위치 데이터로 거리 계산을 수행한다. LBS Server는 계산 결과를 암호문 상태에서 비교하여 사용자의 위치로부터 가장 가까운 위치가 저장되어 있는 k개의 암호문을 결과로서 도출한다. 결과는 LBS Server로부터 사용자에게 반환되며, 사용자는 이를 복호화하여 자신의 질의 결과를 확인한다. 본 방법에서는 Database의 위치 데이터와 사용자의 질의 정보가 모두 암호화된 상태로 Top-k 위치정보서비스를 제공하므로 LBS Server에 대해 사용자와 위치 데이터 정보의 프라이버시가 보존된다. 시뮬레이션에서는, 16개의 위치 정보에 대하여 질의와 거리 연산을 수행하여 사용자의 질의로부터 가장 가까운 3개의 위치를 알아내는 과정을 수행하였다. 그 결과 일반적인 데스크탑 환경에서 약 270시간이 걸려 단기간 내의 실용화는 어려울 것으로 예상되나 이러한 성능 문제는 하드웨어의 발전과 함께 개선될 것이라 생각된다.