• Geotechnical Engineering
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• v.11 no.2
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• pp.19-28
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• 1995

Based on the various test data acquired in the field, the large pressure chamber and the small pressure chamber, uplift behaviors and method of determining the ultimate uplift capacity of pile driven in small pressure chamber were studied. After uplift pile experienced 2 or 3 sudden slip due to increase of uplift load, complete pullout failure was occurred. Thus, it appears that the ultimate uplift capacity could be identified as the load at displacement where first slip occurs. The ultimate uplift capacity might be determined in every test and the disturbance after first uplift test could be recovered by adding one blow of the drop hammer, which had to depend on the model pile capacity.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.432-437
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• 2011

Recently, industry needs a new design of Czochralski(Cz) process for higher productivity with reasonable energy consumption. In this study, we carried out computational simulations for finding out a new optimal design of Cz process with variables which can be applied in real industry such as location of heater, shape of shield and crucible size. Objective process was Cz process which can be produced 8 inch diameter Si ingot for solar cell and we acquired an optimal design for higher productivity, low power consumption with stable production condition. For higher productivity we also change the crucible diameter from 22 inches to 24 inches with changing insulation thickness only because the process housing size could not be changed in industry.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.221-221
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• Annual Conference of KIPS
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• 2016.04a
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• pp.953-955
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• 2016

본 논문은 다중 회귀 분석을 이용하여 3축 가속도센서기반의 활동량을 추정하는 방법을 제안한다. 본 연구를 위해 총 59명의 피 실험자가 자체 제작한 활동량계를 착용한 뒤 트레드밀에서 일정한 속도로 걷는/뛰는 동작을 수행한 신호를 수집하였다. 수집한 3축 가속도 신호의 에너지 값에서 사전에 정의한 특징들을 산출한다. 그 다음 각 특징별로 선형, 지수, 로지스틱 회귀 분석을 적용하여 적합도가 높은 특징을 선정한다. 마지막으로 산출된 회귀식들을 사용하여 다중 회귀 분석 방법으로 활동량을 추정한다. 호흡가스 대사 분석기(K4B2)를 착용한 뒤 동일한 방법으로 실험을 수행 하고 제안한 방법과 정확도를 비교한 결과 제안한 방법의 정확도는 86.38 %로 산출되었다. 이는 기존의 Kim 외 3인의 연구결과[1]보다 2.70 %, Actical의 정확도보다 4.31 % 높은 수치이다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.3
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• pp.138-145
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• 2006

It is well known that the accurate calculation of the field distribution is essential for the design of electrical machines. The analytical techniques for electromagnetic field can quickly and exactly determine airgap magnetic field distribution in electrical machines. Many analytical techniques have been investigated to predict the magnetic field distribution in PM machines equipped with permanent magnets. Using the analytical technique by transfer relations, D. L. Trumper and K. R. Davey already presented the design and analysis of linear permanent-magnet machines and induction machines, respectively. Using the transfer relations (Melcher's general methodology) to describe electromagnetic phenomena, this paper deals with the analysis on the magnetic field distribution due to PM and winding current, the induced voltage and the static torque characteristics in surface-mounted slotless type permanent magnet machine. The validity of the analysis results is confirmed by finite element (FE) analysis.

• KSBB Journal
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• v.24 no.2
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• pp.189-194
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• 2009

In this work, antioxidant substance homoorientin from Pseudosasa japonica and Phyllostachys bambusoides leaves wereextracted using ultrasonic system, and analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) on-line ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) antioxidant screening method. Also, the various experimental variables were the frequency and time of ultrasonic system. From the results, homoorientin was high extracted at the experimental condition of low frequency 35 kHz and time 60 min. And the content of homoorientin in Phyllostachys bambusoides was remarkably higher than that in the Pseudosasa japonica extract.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.132-145
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• 1992

A series of design, theoretical analysis and model test procedures is presented for the development of an axisymmetric stator-propeller system. A preswirl stator is located in front of a propeller in order to improve the propulsion efficiency by cancellation of the slip stream rotational velocity due to the propeller. Model test results show that propulsion efficiency gain due to the symmetric stator-propeller system is about 3% compared to the single propeller. This efficiency gain would increase for full scale application since the pressure drag coefficient of the stator would decrease due to increasement of turbulent intensity behind the hull wake and increasement of Reynolds number.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.4
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• pp.1-10
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• 2002

For the time-domain simulation of incipient breaking waves, usually the boundary integral method has been used so far, and it seems to be successful except a problem of too much computation time. The present paper shows a new computation technique for the simulation of breaking wave experiment. This technique uses the high-order spectral/boundary element method and the boundary integral method in sequence, and reduces the computation time remarkably. The wave generation and energy focusing process is efficiently simulated by the high-order spectral/boundary element method. Only the wave over-turning process is simulated by the boundary integral method. In the example calculation result, salient features of breaking waves such as high particle velocities and accelerations are shown.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.162.2-162.2
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• 2012

한국형 발사체 KSLV-2의 발사능력을 고려하면 달 탐사선의 총 무게는 약 550kg이 된다. 따라서 달 탐사선에 탑재할 수 있는 탑재체 무게를 최대화하기 위해서는 지구에서 달로 가는 천이궤적을 가장 효율적으로 설계하여 연료 소모량을 최소화하여야 한다. 본 연구에서는 최근에 달 탐사 천이궤적으로 가장 많이 사용되고 있는 Weak Stability Boundary 천이궤적에 관해 연구를 수행하였다. Weak Stability Boundary 천이궤적은 지구로부터 출발한 후 원지점 약 1.4 km(지구-태양의 L1 점 근처)까지 비행한 후 태양풍을 통해 에너지를 얻어 근지점 거리를 지구-달 거리만큼 증가시켜 LOI(Lunar Orbit Injection)시 ${\Delta}V$를 최소화하여 달 궤도에 들어가는 방법이다. Weak Stability Boundary 천이방법의 TLI(Trans Lunar Injection) 값은 직접천이 방법의 TLI 값보다 더 크지만 달 궤도 진입에 필요한 LOI ${\Delta}V$값은 25% 정도 덜 든다는 장점이 있다. 이 방법은 일본의 Hiten 탐사선이 최초로 사용하였으며, 달에 도착하기까지 수개월이 걸리는 단점이 있다. Weak Stability Boundary 천이궤적 시뮬레이션을 통해 최대로 절약할 수 있는 연료 소모량을 확인할 수 있었으며, 다른 천이방법들과의 장단점 비교를 통해 한국형 달 탐사선의 지구-달 천이궤적 후보로 사용 될 수 있음을 확인하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.2
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• pp.79-84
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• 2013

In this study, a cold aisle containment system was proposed among various strategies to reduce the energy waste by recirculation air from the hot aisle. To verify the effectiveness of the cold aisle containment system, a test bed which is similar to an actually existing server room was set up in the Internet Data Center(IDC) building. Comparative experiments, conventional open type cooling system and cold aisle containment system were carried out under actual conditions. The result revealed that the range of inlet temperature of the server system was $20{\sim}25^{\circ}C$ in an existing cooling system and the range of inlet temperature dropped below $20^{\circ}C$ by the cold aisle containment system. After all, cold aisle containment system was proved to be the solution for energy saving cooling system.