• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.12 s.105
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• pp.1340-1346
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• 2005

In this study, based on shaking table test results on a seismically isolated bridge model, an inelastic numerical model is refined by using Bouc-Wen model representing the hysteretic behavior of isolators. Seismic responses of isolated bridges are numerically investigated varying with relative stiffness ratio(RSR), which is a ratio of the effective stiffness of isolator to the lateral stiffness of bridge pier, From the results, it is found that an adequate range of relative stiffness ratio could be defined for seismic design of isolated bridges without considering the flexibility of piers.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.4
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• pp.93-104
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• 2000

적충되어 있는 다중 블록 시스템은 역사적 건물이나 문화재등에 자주 사용되고 있다. 이러한 구조시스템은 지진에 매우 취약하고, 특히 세장한 구조물인 경우에는 낮은 수준의 지반가속도에 대해서도 전도가 일어날 수 있다. 지진으로부터 이러한 구조물을 보호할 수 있는 방법중의 하나로써 지진격기받침의 사용을 들 수 있으나, 아직 격리받침이 설치되어 있는 다중블록의 거동에 대해서는 잘 알려지지 않는 실정이다. 이 논문에서는 각각 P-F 시스템, FPS, LRB 시스템이 설치되어 있을때의 세장한 강체 블록의 동적거동에 대해 살펴보았다. P-F 시스템과 FPS에서의 마찰모델은 Coulomb의 마찰법칙을 이용하였도, 상부구조물은 붙음(stick)모드와 록킹(rocking) 모드만이 존재하도록 가정하였다. 충격은 개별요소법(distinct element method, DEM)을 이용해 기술하였고, 조화입력운동에 대한 응답을 조사하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.463-466
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• 2010

A scramjet engine intake model was tested with a storage air heater type hypersonic wind tunnel. In test results, there is no large performance change with the variation of the sidewall configurations. In the isolator performance analysis, pressure distribution of oblique shock train and normal shock train was observed. Unstart limit of the model was also confirmed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.662-665
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• 2004

In this paper, based on shaking table test results on a seismically isolated bridge model, an inelastic numerical model is refined by using Bouc-Wen model representing the hysteretic behavior of isolators. Seismic responses of isolated bridges are numerically investigated varying with relative stiffness ratios, which is a ratio of the effective stiffness of isolator to the lateral stiffness of bridge pier. From the results, it is found that an adequate range of relative stiffness ratio could be defined for seismic design of isolated bridges without considering the flexibility of piers.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.442-448
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• 2003

최근 장대교량의 건설이 증가하고 지진에 대한 관심이 고조되면서 교략의 내진설계와 면진설계가 교량설계의 주요항목으로 자리잡게 되었다. 특히 최근 ILM교량과 같은 다경간 장대교의 경우 지진시 교량의 상부구조와 하부구조를 격리시켜 주기를 변화시키는 LRB를 이용한 면진설계가 주로 이루어지고 있다. 그러나 아직까지 국내에는 Mt5의 거동과 기본성능에 대한 실험데이터가 절대적으로 부족하며, 따라서 그 특성을 엄밀히 검증하지 못한 채 고속도로 및 국도상의 교량에 LRB를 다수 사용하고 있는 현실이다. 본 연구에서는 실교량에 사용될 LRB에 대하여 기본성능 중의 하나인 피로마모시험을 수행함으로써 온도하중과 같은 반복하중에 대한 LRB의 피로거동을 모사하고 피로시험 전.후의 기본성능의 변화를 파악하였다. 이러한 LRB의 기본성능에 대한 실험온 LRB의 성능에 대한 검증과 함께 LRB의 거동에 대한 불확실성을 줄일 수 있는 기본 자료로 축적할 수 있으며, 현재 한국도로공사 도로교통기술원에서 마련중인 지진격리장치(LRB) 성능시험기준(안)의 정립에 기초 자료로참고하고자 한다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.463-470
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• 2006

이 논문에서는 신경망 제어기와 MR 댐퍼를 이용하여 지진하중을 받는 지진격리 벤치마크 구조물의 응답 감소를 위한 반능동 제어방법이 제안되었다. 제안방법 중 신경망 제어기에는 적절한 제어력을 산출하기 위해 가격함수를 기반으로한 학습 알고리즘과 간편한 민감도 계산기법이 도입되었다. MR 댐퍼가 계산되어진 제어력과 비슷한 제어력을 낼 수 있도록 clipped 알고리즘을 이용하였고, 제안된 반능동 신경망 제어방법이 지진격리 장치가 설치된 벤치마크 구조물에 적용되었다. 수치해석에서는 벤치마크 문제를 정의한 논문에서 제공된 수동제어방법이나 예시제어방법과 제안 방법의 제어성능을 비교하였다. 수치해석 결과 제안방법은 지하 변위를 약간 증가시키지만, 각층의 가속도, base shear, building corner drift 등을 매우 효과적으로 줄이는 것으로 판명되었다.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.55-66
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• 2012

The practical way to minimize the greenhouse gas is to reduce the emission of carbon dioxide. For this reason, CCS(Carbon Capture and Storage) technology, which could reduce carbon dioxide emission, has risen as a realistic alternative in recent years. In addition, the researcher is recently working into ways of applying CCS technologies with deep saline aquifer. In this study, the evaluation model on the feasibility of $CO_2$ sequestration in the deep saline aquifer using ANN(Artificial Neural Network) was developed. In order to develop the efficiency-evaluation model, basic model was created in the deep saline aquifer and sensitivity analysis was performed for the aquifer characteristics by utilizing the commercial simulator of GEM. Based on the sensitivity analysis, the factors and ranges affecting $CO_2$ sequestration in the deep saline aquifer were chosen. The result from ANN training scenario were confirmed $CO_2$ sequestration by solubility trapping and residual trapping mechanism. The result from ANN model evaluation indicated there is the increase of correlation coefficient up to 0.99. It has been confirmed that the developed model can be utilized in feasibility of $CO_2$ sequestration at deep saline aquifer.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.48-53
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• 2007

In this paper, a high LO-RF isolation W-band MIMIC single-balanced mixer was designed and fabricated using a branch line coupler and a ${\lambda}/4$ transmission line. The W-band MIMIC single-balanced mixer was designed using the $0.1\;{\mu}m$ InGaAs/InAlAs/GaAs Metamorphic HEMT diode. The fabricated MHEMT was obtained the cut-off frequency($f_T$) of 154 GHz and the maximum oscillation frequency($f_{max}$) of 454 GHz. The designed MIMIC single-balanced mixer was fabricated using $0.1\;{\mu}m$ MHEMT MIMIC process. From the measurement, the conversion loss of the single-balanced mixer was 12.8 dB at an LO power of 8.6 dBm. P1 dB(1 dB compression point) of input and output were 5 dBm and -8.9 dBm, respectively. The LO-RF isolations of single-balanced mixer was obtained 37.2 dB at 94 GHz. We obtained in this study a higher LO-RF isolation compared to some other balanced mixers in millimeter-wave frequencies.

• The Journal of the Korea Contents Association
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• v.14 no.7
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• pp.302-311
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• 2014

The purpose of this study was to investigate on parenting stress, parenting guilt feelings and separation anxiety and alternative care in nurses. Data were collected from nurses with preschooler at 2 hospitals from August 2013 to January 2014. Self reported questionnaires were used to collect data from 163 nurses. There were significant differences according to the age, satisfaction of work place and co-worker, spouse support of parenting in parenting stress, parenting guilt feelings and separation anxiety in common. The majority type of alternative care was surrogate foster home when they went to work. However, there were significant differences according to type of alternative care in parenting stress, parenting guilt feelings and separation anxiety. Particularly, those who use child day-care center and surrogate foster home showed more parenting guilt feelings and separation anxiety in Scheffe post-hoc comparison. As a result, it is needed to be improvement of working conditions and policy for nurses' parenting support to continue work.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.83-90
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• 2016

Despite the ability of biochar to enhance soil fertility and to mitigate greenhouse gas, its carbon sequestration and profit analysis with arable land application have been a few evaluated. This study was conducted to estimate carbon sequestration and to evaluate profit of greenhouse gas mitigation during corn cultivation periods. For the experiment, the biochar application rates were consisted of pig compost(non application), 2,600(0.2%), 13,000(1%), and 26,000(2%) kg/ha based on pig compost application. For predicting soil carbon sequestration of biochar application, it was appeared to be linear model of Y = 0.5523X - 742.57 ($r^2=0.939^{**}$). Based on this equation, soil carbon sequestration by 0.2, 1 and 2% biochar application was estimated to be 1,235, 3,978, and 14,794 kg/ha, and their mitigations of $CO_2$-eq. emissions were estimated to be 4.5, 14.6, and 54.2 ton/ha, respectively. Their profits were estimated at $14.6 for lowest and $452 for highest. In Korea Climate Exchange, it was estimated that the market price of $CO_2$ in corn cultivation periods with 0.2, 1 and 2% biochar application was $35.6, $115.3 and $428.2 per hectare, respectively. For the plant growth response, it was observed that plant height and fresh ear yield were not significantly different among the treatments. Therefore, these experimental results might be fundamental data for assuming a carbon trading mechanism exists for biochar soil application in agricultural practices.