• Proceedings of the KIEE Conference
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• 2006.05a
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• pp.74-77
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• 2006

This research is focused on the development of GIS Diagnostic SYSTEM to prevent accidents beforehand by inspecting the internal defects of GIS (Gas Insulated Switchgear) which is a main power-facility for substations. GIS Diagnostic SYSTEM is categorized as 'Real time on-line test type' and 'Portable test type' depending on the types of testing, it uses PD(partial discharge) which mostly incurs in GIS internal defects, to inspect. As of now, mostly foreign equipments are imported for use due to the lack of the technology localization, and these are installed and operated on only some parts of highly-graded GIS power-facilities such as in 76skv or 345kv for its being expensive. Furthermore, other than foreign equipments being costly, it also has a weak point of very long unavailability in case of Diagnostic system break-down while using, because it takes a comparatively long period of corrective maintenance precesses. We have localized to develop personal real-time multi -functional GIS Diagnostic system which can test on all GIS power-facility comprehensively and economically therefore overcome all these problems mentioned above, a market expansion is expected from the decrease of price and replacing the import equipments in the future. As the equipment was developed to be Personal for the simple ways of installing and utilizing, it can be operated without any complex cable installation like other existing GIS Diagnostic system requires, therefore also decrease the cost of cable installation.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.858-864
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• 2014

Recently, many researches have shown that even photosynthetic light-harvesting pigment-protein complexes can have quantum coherence in their excitonic energy transfer at cryogenic and physiological temperatures. Because the protein supplies such noisy environment around pigments that conventional wisdom expects very short lived quantum coherence, elucidating the mechanism and searching for an applicability of the coherence have become an interesting topic in both experiment and theory. We have previously studied the quantum coherence of a phycocyanin 645 complex in a marine algae harvesting light system, using Poisson mapping bracket equation (PBME). PBME is one of the applicable methods for solving quantum-classical Liouville equation, for following the dynamics of such pigment-protein complexes. However, it may suffer from many defects mostly from mapping quantum degrees of freedom into classical ones. To make improvements against such defects, benchmarking targets with more accurately described dynamics is highly needed. Here, we fall back to reduced hierarchical equation of motion (HEOM), for such a purpose. Even though HEOM is known to applicable only to simplified system that is coupled to a set of harmonic oscillators, it can provide ultimate accuracy within the regime of quantum-classical description, thus providing perfect benchmark targets for certain systems. We compare the evolution of the density matrix of pigment excited states by HEOM against the PBME results at physiological temperature, and observe more sophisticated changes of density matrix elements from HEOM. In PBME, the population of states with intermediate energies display only monotonically increasing behaviors. Most importantly, PBME suffers a serious issue of wrong population in the long time limit, likely generated by the zero-point energy leaking problem. Future prospects for developments are briefly discussed as a concluding remark.

• Transactions of Materials Processing
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• v.25 no.1
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• pp.12-20
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• 2016

Press machines and dies are commonly used for 3D curved sheet forming. Using conventional die forming can cause economic problems since various modifications of the die shape are required depending on the product shape. Various types of flexible forming such as multi-point dieless forming (MDF), flexible incremental roll forming have been developed to improve the needed process flexibility. Although MDF can reduce the production cost using reconfigurable dies, it still has significant material loss. Drawbacks such as wrinkling, dimpling, and forming errors can also occur despite continuous investigations to mitigate these defects. A novel sheet forming process for 3D curved surfaces, a flexibly-reconfigurable roll forming (FRRF), has been recently proposed to overcome the economic and technical limitations of current practice. FRRF has no limitation on blank size in the longitudinal direction, and also minimizes or eliminates forming defects such as wrinkling and dimpling. Feasibility studies of FRRF have been conducted using FE simulations for multi-curved shapes and various sheet thicknesses. Therefore, the fabrication of a FRRF apparatus is required for any follow-up studies. In the current study, experiments with reconfigurable rollers were conducted using a simple design pre-FRRF apparatus prior to fabricating the full size FRRF apparatus. There are three candidates for the reconfigurable roller: a bar-type shaft, a flexible shaft, a ground flexible shaft. Among these candidates, the suitable reconfigurable roller for FRRF is determined through various forming tests.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.5
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• pp.333-339
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• 1999

It is well recognized that ultrasonic technique is one of the most common and reliable nondestructive evaluation techniques for quantitative estimation of defects in structures. For the quantitative and accurate estimation of internal defects. the characteristics of scattered ultrasonic wavefields must be understood. In this study. the scattered near-field and far-field due to a circular cavity embedded in infinite media subjected to incident SH-waves were calculated by the boundary element method. The frequency response of the scattered ultrasonic far-field was transformed into the time-domain signal by obtaining its inverse Fourier transform. It was found that the amplitude of time-domain signal decreases and its time delay increases as the distance between the detecting point of ultrasonic scattered field and the center of internal cavity increases.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.1
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• pp.27-35
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• 2009

In this paper, we study the classification of steam generator tube defects using an improved feature extraction. We consider 4 axisymmetric defect patterns of tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. From those generated ECT signals, we propose new feature vectors that include an angle between the two points where the Maximum impedance and half the Maximum impedance, and angles between Maximum impedance point and 10%, 20%, 30%, 40% of Maximum impedance points. Also, multi-layer perceptron with one hidden layer is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves an improved defect classification performance in terms of Maximum Error and mean square Error.

• Archives of Reconstructive Microsurgery
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• v.19 no.1
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• pp.21-28
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• 2010

Purpose: To report the clinical results of the use of arterialized venous free flaps in reconstruction in soft tissue defects of the finger and to extend indications for the use of such flaps based on the clinical experiences of the authors. Materials and Methods: Eighteen patients who underwent arterialized venous free flaps for finger reconstruction, between May 2007 and July 2009 were reviewed retrospectively. The mean flap size was 4.7${\times}3.2$ cm. The donor site was the ipsilateral volar aspect of the distal forearm in all cases. There were 8 cases of venous skin flaps, 5 cases of neurocutaneous flaps, 4 cases of tendocutaneous flaps, 1 case of innervated tendocutaneous flap. The vascuality of recipient beds was good except in 4 cases (partial devascuality in 2, more than 50% avascuality (bone cement) in 2). Results: All flaps were survived. The mean number of included veins was 2.27 per flap. Mean static two-point discrimination was 10.5 mm in neurocutaneous flaps. In 3 of 5 cases where tendocutaneous flaps were used, active ROM at the PIP joint was 60 degrees, 30 degrees at the DIP joint and 40 degrees at the IP joint of thumb. There were no specific complications except partial necrosis in 3 cases. Conclusions: An arterialized venous free flap is a useful procedure for single-stage reconstruction in soft tissue or combined defect of the finger; we consider that this technique could be applied to fingers despite avascular recipient beds if the periphery of recipient bed vascularity is good.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.347-351
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• 2020

A material changes its physical and chemical properties through the interaction with radiation and also the neutrons, which is electronically neutral so that the penetration depth is relatively deeper than that of other radioactive way including alpha or beta ray. Therefore, the radiation damage by neutron irradiation has been intensively investigated for a long time with respect to the safety of nuclear power plants. The damage induced by neutron irradiation begins with the creation of point defects in atomic scale in the unit of picoseconds, and their progress pattern can be characterized by microstructural defects, such as dislocation loops and voids. Their morphological characteristics affect the properties of neutron-irradiated materials, therefore, it is very important to predict the microstructure at a given neutron irradiation condition. This paper briefly reviews the evolution of radiation damage induced by neutron irradiation and introduces a phase-field model that can be widely used in predicting the microstructure evolution of irradiated materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.278-281
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• 2003

The p-CIn2Te4 single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. From the photoluminescence spectra of the as-grown CdIn2Te4 crystal and the various heat-treated crystals, the (Do, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the CdIn2Te4:Cd, while the (Ao, X) emission completely disappeared in the CdIn2Te4:Cd. However, the (Ao, X) emission in the photoluminescence spectrum of the CdIn2Te4:Te was the dominant intensity like an as-grown CdIn2Te4 crystal. These results indicated that the (Do, X) is associated with VTe acted as donor and that the (Ao, X) emission is related to VCd acted as acceptor, respectively. The p-CdIn2Te4 crystal was found to be obviously converted into the n-type after annealing in the Cd atmosphere. The origin of (Do, Ao) emission and its TO phonon replicas is related to the interaction between donors such as VTe or Cdint, and accepters such as VCd or Teint. Also, the In in the CdIn2Te4 was confirmed not to form the native defects because it existed in the stable form of bonds.

• Archives of Reconstructive Microsurgery
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• v.25 no.2
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• pp.37-42
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• 2016

Purpose: Soft tissue coverage of the distal leg and ankle region represents a surgical challenge. Beside various local and free flaps, the perforator flap has recently been replaced as a reconstructive choice because of its functional and aesthetic superiority. Although posterior tibial artery perforator flap (PTAPF) has been reported less often than peroneal artery perforator flap, it also provides a reliable surgical option in small to moderate sized defects especially around the medial malleolar region. Materials and Methods: Seven consecutive patients with soft tissue defect in the ankle and foot region were enrolled. After Doppler tracing along the posterior tibial artery, the PTAPF was elevated from the adjacent tissue. The average size of the flap was $28.08{\pm}9.31cm^2$ (range, 14.25 to $37.84cm^2$). The elevated flap was acutely rotated or advanced. Results: Six flaps survived completely but one flap showed partial necrosis because of overprediction of the perforasome. No donor site complications were observed during the follow-up period and all seven patients were satisfied with the final results. Conclusion: For a small to medium-sized defect in the lower leg, we conducted the close-by islanded PTAPF using a single proper adjacent perforator. Considering the weak point of the conventional propeller flap, this technique yields much better aesthetic results as a simple and reliable technique especially for defects of the medial malleolar region.

• Journal of Sensor Science and Technology
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• v.15 no.6
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• pp.379-385
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• 2006

Single crystal of p-$CdIn_{2}Te_{4}$ was grown in a three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by x-ray diffraction and photoluminescence measurements. From the photoluminescence spectra of the as-grown $CdIn_{2}Te_{4}$ crystal and the various heat-treated crystals, the ($D^{o}$, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the $CdIn_{2}Te_{4}$:Cd, while the ($A^{o}$, X) emission completely disappeared in the $CdIn_{2}Te_{4}$:Cd. However, the ($A^{o}$, X) emission in the photoluminescence spectrum of the $CdIn_{2}Te_{4}$:Te was the dominant intensity like in the as-grown $CdIn_{2}Te_{4}$ crystal. These results indicated that the ($D^{o}$, X) is associated with $V_{Te}$ which acted as donor and that the ($A^{o}$, X) emission is related to $V_{Cd}$ which acted as acceptor, respectively. The p-$CdIn_{2}Te_{4}$ crystal was obviously found to be converted into n-type after annealing in Cd atmosphere. The origin of ($D^{o},{\;}A^{o}$) emission and its to phonon replicas is related to the interaction between donors such as $V_{Te}$ or $Cd_{int}$, and acceptors such as $V_{Cd}$ or $Te_{int}$. Also, the In in the $CdIn_{2}Te_{4}$ was confirmed not to form the native defects because it existed in a stable bonding form.