• The Korean Journal of Financial Management
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• v.19 no.2
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• pp.211-231
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• 2002

본 연구의 목적은 VECM(Vector Error Correction Model)과 인공지능모형(Artificial Neural Networks)을 이용하여 우리나라 증권시장과 거시경제 변수들과의 장기적 관계에 대한 설명력을 비교해보고자 함에 있다. VECM이 APT(Arbitrage Pricing Theory)에 기초를 둔 선형동학모형이라고 한다면, 인공지능모형은 비모수적 비선형모형이라는 점에서, 두 방법론의 분석결과를 직접 비판하는 것은 의미있는 연구라고 할 수 있다. 인공지능모형을 주로 활용하는 선행연구들에 의하면, 증권시장은 시장의 특이패턴들로 인해 계량경제학적 접근인 선형 모형보다는 인공지능모형을 통해 증권시장의 움직임을 설명하고 예측하는 것이 더 바람직할 수도 있다는 것이다. 따라서, 본 연구에서는 VECM분석에서 자료의 안정성을 검증하고, 공적분 백터를 발견한 이후, 장기적 균형관계의 실증적 분석을 하였다. 그리고, 인공지능모형에서는 delta rule과 Sigmoid 함수를 이용한 GRNN(General Regression Neural Net)과 Back-Propagation등의 방법들을 활용하였다. 이러한 분석결과, Back-Propagation 모형이 다른 모든 모형들보다도 더 우수한 설명력을 보여주고 있었다. 이러한 결과들은 인공지능모형이 동태적인 선형 모형보다도 더 우수한 설명력을 제공할 수 있는 가능성을 보여주고 있었다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.11
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• pp.64-69
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• 1997

We have shown that the Hough transform filter can be easily obtained by repeatedly recording one line segment pattern holographically by use of rotational multiplexing. With this filter, one can get resutls of the hough transform in the time of light propagation. To demonstrate our method experimentally, the hough transform filter for 18 different rottion angles was recorded, and experimental transform results were compared with simulated ones for a few input patterns. By introducing a compensation process for the non-uniformity of both the input plane wav eand the diffraction efficiency of each hologram. It is possible to get more precise transform results.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.285-291
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• 2003

An experimental method to measure Q-parameter in-situ is described. The basic idea comes from the fact that the side necking near a crack tip indicates the loss of stress triaxiality, which can be scaled by Q. From the out-of-plane displacement and the in-plane strain near the surface of side necking, stress field averaged through the thickness is calculated and then Q is determined from the difference between the stress field and the HRR field corresponding to the identical J-integral. To prove the validity, three-dimensional finite element analysis has been performed for a CT configuration with side-groove. Q-value which was calculated directly from the near-tip stress field is compared with that determined by simulating the experimental procedure according to the proposed method, that is, the Q-value determined from the lateral displacement and the inplane strain. Also, the effect of location where the displacement and strain are measured is explored.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.1021-1028
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• 2004

Kim et al. suggested an experimental method to determine the Q parameter in situ from the out-of-plane displacement and the in-plane strains on the surface of side necking near the crack tip. In this paper, the procedure to evaluate the stress triaxiality near a crack tip such as the Q parameter is to be polished in the details for simplicity and accuracy. That is, Q and hydrostatic stress are determined only from the out-of-plane displacement, but not using in-plane strain, which is hard to measure. And also, the plastic modulus is determined by an alternative way. Through three-dimensional finite element analyses for a standard CT specimen with 20% side-grooves, the validities of the new procedures are examined in comparison to the old ones. The effect of location where the displacements are measured to determine the stress triaxiality is explored.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.898-904
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• 2003

Using the modified Irwin model and the modified Dugdale model, the plastic zone size near the interface crack tip in a ductile layer bonding two dissimilar elastic substrates is predicted. Validity of the models is examined by finite element method. The effects of several factors such as the mode mixity, T-stress and material properties are explored. The plastic zone size significantly decreases with the Poisson's ratio of the ductile layer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.11 s.170
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• pp.2078-2086
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• 1999

Fracture behaviors of an interface crack in a ductile layer sandwiched by rigid substrates are analyzed by finite element method. Several fracture mechanisms and the corresponding criteria are examined. And the crack growth behavior and fracture toughness are predicted. As the results, various crack growth procedures such as the crack jump to the other interface on the opposite side, the creation of a new crack far from the initial crack front, and the asymmetric relation of fracture toughness vs. mode mixity ($J_c$-$\Phi$) can be successfully explained.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.79-83
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• 1999

We implemented a system that can change laser beam directions rapidly by controlling the galvano-mirror, on which a mirror is mounted, with a computer. We show that a laser projection can be realized by programming our system properly, and that it can also be used for multiplexing 2-dimensional image information in the data storage of holographic memories efficiently.

• Korean Journal of Environment and Ecology
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• v.14 no.4
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• pp.311-323
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• 2001

계룡산국립공원의 관속식물상을 조사한결과 111과 346속 509종 69변종 10품종 1교잡종 총 589종으로 밝혀졌다. 대상지역은 식물구계지리학적으로 한반도 온대중부지역에 속하나 굴피나무, 감태나무, 사람주나무, 나도밤나무, 자귀나무, 대팻집나무, 비목나무, 정금나무 등 온대남부계 수종이 많은 서식하는 특징을 보여주었다. 대상지역의 특징적인 식물군락이나 희소적 가치가 있는 식물종은 동학사 주변의 느티나무군락과 삼볼봉 등산로 주변의 구실사리, 바위손군락와 정상부 능선에 서식하고 있는 피나무 등으로 이들에 대해서는 지속적인 관심과 보전이 필요하다. 이번 조사에서 미국자리공, 개망초 등이 등산로 주변으로 다수 출현하고 있으므로 귀화식물종에 대한 모니터링도 지속적으로 이루어져야 할 것으로 판단되었다.

• Korean Journal of Environment and Ecology
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• v.14 no.4
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• pp.324-331
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• 2001

본 연구는 계룡산국립공원을 방문한 이용객들의 전반적이 이용형태, 이용만족도, 그리고 이용 및 관리 관련 속성에 대한 태도를 파악함으로서 효율적인 공원관리방안 수립에 필요한 기초 정보의 제공에 그 목적이 있다. 이를 위해 응답자 직접기입 방식의 설문조사가 계룔산국립공원의 3개지역 (동학사. 갑사, 신원사)를 방문한 316명의 이용객을 대상으로 실시되었다. 응답자의 사회경제적 특성은 타국립공원에서 실시된 조사결과와 유사한 경향을 보였다. 계룡산국립공원은 휴식 목적의 방문비율이 가장 높았으며, 동반자 유형에 있어서 가족동반 비율이 가장 높게 나타났다. 또한 응답자들은 도착지에서의 이용정보의 질과 제공수단에 불만족을 나타냈으며 응답자들이 현지에서 느낀 혼잡의 정도는 심하지 않은 것으로 나타났다. 이와 함께 전반적인 휴양만족도는 비교적 긍정적으로 평가되었다.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.205-215
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• 2020

Objective: The purpose of this study was to investigate the relative angles and cross-correlation between body segments and ski among four alpine ski turning techniques. Method: 19 alpine ski instructors participated in this study. Each skier asked to perform 4- types of turning technique, classified by radius and level. 8 inertial measurement units were used to measure orientation angle of segment and ski on the anteroposterior and vertical axis. Results: Significant differences were found between types of turning in the segments-ski relative angle on the anteroposterior and vertical axis (p<.05). Although, cross-correlation showed a high correlation between angles of segment and ski, there were significant differences between types of turning. Conclusion: Based on our results, the relative movement and timing between each segment and ski is different according to the turning techniques, so the training methods should be applied differently.