• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06a
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• pp.159-164
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• 1999

Homogeneous but distinct visual objects having low-contrast boundaries are usually merged in most of the segmentation algorithms. To alleviate this problem, an efficient image segmentation algorithm based on a bottom-up approach is proposed by using spatial domain information only. For initial image segmentation, we adopt an efficient marker extraction algorithm conforming to the human visual system. Then, two region-merging algorithms are successively applied so that homogeneous visual objects can be represented as simple as possible without destroying low-contrast real boundaries among them. The resultant segmentation describes homogeneous visual objects with few regions while preserving semantic object shapes well. Finally, a size-based region decision procedure may be applied to represent complex visual objects simpler, if their precise semantic contents are not necessary. Experimental results show that the proposed image segmentation algorithm represents homogeneous visual objects with a few regions and describes complex visual objects with a marginal number of regions with well-preserved semantic object shapes.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.74-80
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• 2007

This paper proposes the novel open-fault detection/isolation scheme of inverter switch in two-phase excited VSI. This scheme identify open-fault using voltage sensor at lower switches of each phase according to the operating mode. It has benefit of simple implementation, fast detection and robustness in the load so that stab of the system is improved. Also, at faulty mode, it minimizes faulty effect and makes possible continuous operation through the reconfiguration procedure applying four-switch operation. The validity of proposed fault detection scheme is verified by experimental results.

• Journal of Power Electronics
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• v.18 no.1
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• pp.277-288
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• 2018

Wireless inductive power transfer (IPT) technology is used in many applications today. A compact and high-frequency primary side inverter is one of the most important parts of a WPT system. In this study, a modified class EF-type voltage-fed multi-resonant inverter has been proposed for WPT application at a frequency range of 85-100 kHz. Instead of an infinite input choke inductor, a resonant inductor is used to reduce loss and power density. The peak voltage stress across the MOSFET has been reduced to almost 60% from a class-E inverter using a passive clamping circuit. A simple yet effective design procedure has been presented to calculate the various component values of the proposed inverter. The overall system is simulated using MATLAB/SimPowerSystem to verify the theoretical concepts. A 500-W prototype was built and tested to validate the simulated results. The inverter exhibited 90% efficiency at nearly perfect alignment condition, and efficiency reduced gradually with the misalignment of WPT coils. The proposed inverter maintains zero-voltage switching (ZVS) during considerable load changes and possesses all the inherent advantages of class E-type inverters.

• The Korean Journal of Applied Statistics
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• v.20 no.3
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• pp.605-618
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• 2007

Adaptive sampling design is the selection procedure which depends on observed values of the variable of interest. It is the method which could be applied to the rare and unapproachable population. Adaptive cluster sampling strategies are more efficient than simple random sampling on equivalent sample size. Adaptive sampling with new estimators through the Rao-blackwell method have lower variance than Horvitz-Thompson (HT) and Hansen-Hurwitz (HH). Also, to determine suitable sample size, it was used expected sample and the method finding appropriate sample size by changing initial sample size were studied.

• Archives of Plastic Surgery
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• v.34 no.1
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• pp.88-92
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• 2007

Purpose: Free nipple graft reduction mammaplasty is a simple and effective way to reduce huge breasts. However, this technique is frequently criticized for producing poor projection and hypopigmentation of the nipple areola complex(NAC). Methods: Sixty three patients(126 breasts) underwent the procedure from 1998 to 2005. Authors' method is similar with the modified Gradinger's technique except the keyhole pattern. After skin flap closing, the position of NAC is determined considering symmetry. The NAC is initially harvested and then resection of the breast followed, leaving a deepithelized inferior parenchymal pedicle($5{\times}5cm$). The upper point of inferior pedicle is sutured to the fascia of the pectoralis to produce the upper bulge. The nipple is replaced as a free and composite graft. Results: An average of 823grams of breast tissue per breast was removed. There was no major complications. All grafted nipples showed long lasting projection. And also, all NAC eventually regained their normal color except for 3 patients who needed medical tattoos. The overall results were good and patient satisfactory score was high. Conclusion: This useful technique greatly enhances long lasting projection and recovers nipple color.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.241-244
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• 2005

Though the history of finite element analysis in field of powder metallurgy is not short, industrial engineer is still being dependent on the trial and error approach based on engineer's experience in selecting process conditions. This problem is mainly due to the difficulty in establishing models for the behavior of a powder compact during compaction and sintering as well as finding material parameters for the models and the absence of CAE software with which industrial engineer can easily investigate the effect of process conditions on the quality of product. Therefore, we established very simple and cheap procedure to find material parameters for powder compaction behavior and implemented it in self-developed commercial CAE software for powder metallurgy, PMsolver. Basically, the development strategy of PMsolver lies on simplification and convenience so as for industrial engineers to use it with least training. Using PMsolver, optimal process conditions were found for some geometry and powders. Prior to process condition design, the accuracy of finite element analysis was verified.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.2
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• pp.363-369
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• 2005

The theory of Hwa Acupuncture Therapy (HAT), called Hwa Chim Therapy, is a part of the Five Elements Theory unique to Korea. HAT, created and developed by Jaehoon Song, integrates the victor-vanquished as well as the son-mother relationship of the Five Elements of breakdown and restoration of balance between yin and yang. And also, it provides resources and data on The seventy fifth Difficulty(75難) of Classic on Difficulty - Nan Jin 75. HAT establishes objectiveness and accuracy of diagnosis based upon the traditional method and procedure of pulse taking. In HAT, a person's state of illness is diagnosed by applying the comparative examination of the palpitation of the pulse. It is fact that the pulse varies according to the state, and that HAT treatment has proven the positive results by using the victor-vanquished relationship of Classic on Difficulty-Nan Jin 75. Despite a concise and simple theory, Hwa Chim is very effective in treating a wide range of illnesses, and thus it has gained an increasing attention of many scholars and practitioners in the field of traditional Korean oriental medicine. However, it is the first theoretical attempt to the clinical research and scientific methodology of Ohaeng Hwa Chim, and more active Hwa Acupuncture R&D is being conducted nationwide.

• Journal of Preventive Medicine and Public Health
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• v.22 no.4 s.28
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• pp.486-494
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• 1989

Lead, iron, and zinc concentrations in whole blood were determined by atomic absorption spectrophotometry, using a simple one-step dilution procedure, which were measured in 3 groups, 98 officers unexposed to dust or to metal, 58 coal miners without pneumoconiosis, and 113 coal workers' pneumoconiosis (CWP) patients. The results were as follows : 1. The precisions (C. V.%) of lead, iron, and zinc in blood were $12.65{\pm}6.95%,\;1.47{\pm}1.25%\;and\;6.35{\pm}3.34%$, respectively. 2. Lead and zinc in blood showed the log-normal distribution unlike iron in blood which showed normal distribution. 3. Lead, iron, and zinc concentrations in blood of 3 groups were follows : There was significant difference of concentration for zinc in blood by groups statistically. 4. The difference of lead, iron, and zinc concentrations in blood was not significant (p>0.05) by profusion on chest radiographs.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.205-213
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• 1987

A linear thermoviscoelastic material model, whose basis is on incremental constitutive equation that takes complete strain and temperature histories into account, is derived and computerized in the finite element code. The thermoviscoelastic F.E.M. code which is intended primarily to analyze the cylinder model during the cool-down period, embodies the assumption of linearly elastic bulk and visco-elastic shear responses, thermo-rheologically simple response to temperature change and isotropic thermal expansion. The verification of computer program is accomplished by first testing it against a closed form solution of A.M. Freudenthal & M. Shinozuka's. The stress and strain analyses of five cylindrical models are presented and compared with experimental results. Analytical results are good agreement with experimental results. Margins of safety are evaluated and its allowable ranges are presented.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.173-183
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• 1998

An optimization procedure to find the inlet concentration profile that yields the most uniform deposition rate in a cylindrical CVD chamber has been developed. Assuming that the chemical reaction time is negligibly small, a SIMPLE based finite-volume method is adopted to solve the fully elliptic equations for momentum, temperature, and concentration. The inlet concentration profile is expressed by a linear combination of Chebyshev polynomials and the coefficients of which are determined by the local random search technique. It is shown that the present method is very effective in improving the uniformity of the deposition rate, especially when Re is high and/or the wafer is placed close to the inlet. The optimal profiles have been obtained for various Re, Gr, and geometry combinations.