• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.291-297
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• 2006

The equilibrium structures, relative energies and NBO analyses for the possible conformations and transition states which can exist on the internal rotation of CPDFB and CPCFB molecules have been investigated using DFT and ab initio methods with various basis sets. The interaction between bonding orbital ((C1-C3, C2-C3)) and antibonding orbital (n*(B9) and *(B9-Cl11)) was the main characteristic hyperconjugation in both molecules. In addition, the stabilization energy of CPDFB was 6.63kcal/mol and that of CPCFB was 6.97(E-form)/6.79(Z-form) kcal/mol for each conformation. The rotational barriers by internal rotation of BF2- and BFCl- functional groups were evaluated to be 5.3~6.7kcal/mol and 5.7~6.5kcal/mol respectively, which showed good agreement with the experimental values reported by previous dynamic NMR study. Finally, Z-form was more stable than E-form by 0.2 kcal/mol in CPCFB molecule and therefore Z-form was confirmed as global minimum.

• The Journal of the Korea Contents Association
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• v.12 no.11
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• pp.1-8
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• 2012

The application of object recognition technology has been increased with a growing need to introduce automated system in industry. However, object transformed by noises and shadows appeared from illumination causes challenge problem in object detection and recognition. In this paper, an illumination invariant object detection using a DoG filter and adaptive threshold is proposed that reduces noises and shadows effects and reserves geometry features of object. And also, rotation invariant object recognition is proposed that has trained with neural network using classes categorized by object type and rotation angle. The simulation has been processed to evaluate feasibility of the proposed method that shows the accuracy of 99.86% and the matching speed of 0.03 seconds on ETRI database, which has 16,848 object images that has obtained in various lighting environment.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1125-1134
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• 2007

In this paper, we propose a new approach for rotation invariant texture classification based on Gabor wavelet. Conventional methods have the low correct classification rate in large texture database. In our proposed method, we define two feature groups which are the global feature vector and the local feature matrix. The feature groups are output of Gabor wavelet filtering. By using the feature groups, we defined an improved discriminant and obtained high classification rates of large texture database in the experiments. From spectrum symmetry of texture images, the number of test times were reduced nearly 50%. Consequently, the correct classification rate is improved with $2.3%{\sim}15.6%$ values in 112 Brodatz texture class, which may vary according to comparison methods.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.287-289
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• 1998

실시간 스케줄러는 대역폭, 필요 버퍼량 등과 같은 네트워크 자원을 효율적으로 이용하면서 한정된 통신지연(bounded delay)을 제공해야 한다. 최근 이러한 제한 조건을 만족시키기 위해서 많은 스케줄링 방법론이 제시되었다. 그중EDF 스케줄링 방법론이 최적의 성능을 갖는 것으로 알려져있다. 그러나 EDF스케줄링 방법론은 "sort"나 "search"와 같은 연산작업을 수행함으로서, 과다한 오버헤드를 발생시킨다. Rotating Priority Queues(RPQ) 스케줄러는 EDF 연산 작업 없이 EDF스케줄러에 근접한 성능을 갖는 스케줄러이다. 그러나 RPQ스케줄러는 과다한 버퍼량을 필요로 한다. 본 논문에서는 이러한 문제저？ㄹ 해결하기위해서 Multiple Rotating Priority Queues(MRPQ)스케줄러를 제시한다. MRPQ스케줄러는"blick queue"라는 새로운 개념을 이용하여 회전 우선 순위 queue를 다중 계츨으로 구성한다. 이렇게 구성된 MRPQ 스케줄러는 RPQ스케줄러에서 필요한 버퍼량의 반정도의 버퍼량만을 사용하여 RPQ스케줄러와 동일한 동작을 수행한다. 또한 MRPQ스케줄러는 RPQ스케줄러와 동일한 최대 지연시간을 제공한다.러는 RPQ스케줄러와 동일한 최대 지연시간을 제공한다.

• Proceedings of the KSRS Conference
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• 2008.03a
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• pp.3-6
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• 2008

본 논문에서는 레일형 GB-SAR의 단점을 극복하고자 차량에 원형레일을 탑재하여 신속한 기동을 확보하고 합성구경의 길이를 늘리며 영상영역을 확장한 Arc-SAR의 설계안을 제시한다. 하드웨어 측면에서 살펴보면, 밴형 차량의 상부에 원형레일을 설치하고 마이크로파 송, 수신 안테나를 탑재한 후 레일 위를 1mm 이내의 정밀도로 이동시키며, 자료를 획득하게 된다. 이때 안테나에 연결된 동축 케이블은 차량 내부의 송, 수신장치에 연결되는데 RF대역에서 완벽히 작동하는 슬립링이 없기 때문에 내부 송, 수신 장치를 턴 테이블위에 장착하여 외부 안테나의 이동과 동일한 각도로 회전하여, 동축 케이블의 꼬임을 방지하게 된다. 송, 수신 장치의 구성은 벡터 네트워크 분석기를 기반으로 마이크로파 앰프, 마이크로파 스위치로 구성되며, 통합 제어 소프트웨어를 통해 외부 안테나의 이동과 함께 제어된다. 한편, Arc-SAR 영상의 구현은 원형레일을 따라 얻어지는 합성구경의 기하학적인 특수성을 감안하여 최초로 시도될 것이다. 이 시스템은 RTK-GPS를 장착하여 지반변형 모니터링 시 차량 이동 오차를 최소화 하고자 하며, 이외에 고정형 산란체를 이용하여 차량 이동 오차를 보정하고자 한다. 또한 AWS (Automatic Weather System)을 장착하여 위상의 대기보정을 동시에 수행할 것이다. 이 시스템은 차량 탑재에 의한 기동성의 확보로 침수나 침하 등 긴급 재난 지역에 즉각적인 대응이 가능하며, 대형 구조물의 주기적인 변형 모니터링 등에 활용성이 클 것이다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.209-214
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• 2011

A method to detect rotor mass imbalance, which is one of the typical faults of wind turbine, is presented for effective condition monitoring of wind turbine. Dynamic analysis for a three-bladed horizontal-axis wind turbine was carried out with adding mass to a blade for inflicting the rotor mass imbalance. It has been found that the added mass induce a resulting centrifugal force to nacelle and this leads to a transverse (relative to the rotor axis) oscillation of the nacelle. It has been also found that the amplitude of the oscillation is almost linearly increased as the added mass is increased.

• Tribology and Lubricants
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• v.36 no.3
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• pp.168-192
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• 2020

In recently designed diesel engines, the running conditions for piston-pin bearings have become severe because of the higher combustion pressure and increased temperature. Moreover, the metal removal from the bushing material has strongly reduced the ability of the antifriction material to accept asperity contacts. Therefore, it is necessary to find ways of reducing wear scar on the connecting-rod small-end bushing and piston-pin boss bearing related to the higher combustion pressure on the power cell of an engine. In this work, the position and level of material removal from the surfaces of the bushing and bearing under such severe operating conditions - for example, maximum power and torque conditions of a passenger car diesel engine - are estimated for several combinations of surface roughness. First, piston-pin rotating motion is investigated by calculating the friction coefficient at piston-pin bearings, the oil film thickness, and the frictional torques induced by hydrodynamic shear stress. Subsequently, the wear scarring on the surfaces of a connecting-rod small-end bushing and two piston-pin boss bearings related to piston-pin rotational motion is numerically calculated under the maximum power and torque operating conditions. This work is helpful to determine the reasonable surface roughness of the bushing and bearing for reducing wear volume occurring at the interface between a bearing and a shaft.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.637-646
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• 2016

This study is to investigate the influence of hydrogen attack and UNSM on fatigue behaviors of the Inconel 718 alloy. The decrease of the fatigue life between the untreated and the hydrogen attacked material is 10-20%. The fatigue lives of hydrogen attacked specimen decreased without a fatigue limit, similar to those of nonferrous materials. Due to hydrogen embrittlement, about 80% of the surface cracks were smaller than the average grain size of $13{\mu}m$. Many small surface cracks caused by the embrittling effect of hydrogen attack were initiated at the grain boundaries and surface scratches. Cracks were irregularly distributed, grew, and then coalesced through tearing, leading to a reduction of fatigue life. Results revealed that the fatigue lives of UNSM-treated specimens were longer than those of the untreated specimens.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.686-693
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• 2013

Based on a substrate integrated waveguide(SIW) and a complementary split ring resonator(CSRR), electrically small antennas are proposed in this paper. Antenna's electrical size is reduced by introducing both CSRR and the eighth-mode substrate integrated waveguide(EMSIW). The EMSIW occupies only 12.5 % of the conventional SIW at the same dominant resonant frequency. In addition, the resonant frequency of the antenna is varied by rotating the CSRR on the EMSIW while keeping the same radiation patterns. The resonant frequency is changed from 4.74 GHz to 5.07 GHz by varying orientation of the CSRR from 0 to 360 degree. Unidirectional radiation patterns are observed and the measured peak gains are from 4.50 to 5.92 dBi.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.73-80
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• 2019

This study analyzed the relevance between investment horizons of foreign investors and Book-Tax Difference. To do this, we measured investment horizons of foreign investors as the investment-turnover of foreign investors. We use the sample of 3,025 firm-year Korea listed companies belonging to non-financial corporate sector during 2011-2016. The results of empirical analyses show that investment horizons of foreign investors has a negative relevance with Book-Tax Difference. This result indicates that the firm have a long-term foreign investors has a good Accounting Earning's Quality than the firm have a short-term foreign investors. This study is expected to provide useful information by suggesting the need for more incentive for the long-term foreign investors. And Our Study has a contribution that this study extended prior research on foreign investors by utilizing investment horizons of foreign investors.