• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.775-786
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• 1992

Studies are made of the turbulent separation bubble in a two-dimensional semi-infinite blunt plate aligned to a uniform free stream when the oncoming free stream contains a pulsating component. The discrete-vortex method is applied to simulate this flow situations because this approach is effective to represent the unsteady motions of turbulent shear layer and the effect of viscosity near the solid surface. The two key external paramenters in the free stream, i.e., the amplitude of pulsation, A, and the frequency parameter St[=fH/ $U_{1}$], are dealt with in the present numerical computations, A particular frequency gives a minimum reattachment which is related to the drag reduction and the most effective frequency is dependent on the most amplified shedding frequency. The turbulent flow structure is scrutinized. A comparison between the unperturbed flow and the perturbed at the particular frequency of the minimum reattachment length of the separation bubble suggests that the large-scale structure is associated with the shedding frequency and the flow instabilities.

• Journal of Korean Medicine for Obesity Research
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• v.12 no.2
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• pp.8-16
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• 2012

Objectives: This study is designed to report the correlation between Body Mass Index(BMI), Heart Rate Variability(HRV), stess, drinking alcohol, coffee and smoking. Methods: From 1st January 2010 to 31st December 2012, We tested on 458 patients who hospitalized in Cheong Yeon Korean Medicine Hospital for reducing their weights, then we collected the statistical analysis with the result of their HRV and the special survey. Results: This experiment was studied on total 458 patients, 27 were men and 431 were women. The average of the age of men was $28.23{\pm}4.22$ and $24.31{\pm}385$ was women. There were significant differences in BMI, Low frequency(LF), High frequency(HF), stress score, frequency of drinking alcohol, smoking and drinking coffee followed by their ages. When we looked at the correlation between obesity with smoking and drinking coffee, we can see that the BMI increased, the frequency of drinking alcohol was decreased, however there were no statistic correlation in smoking and drinking coffee with BMI. Conclusions: With the result of HRV, we can suggest the BMI and stress score are correlated each other but we need further studies about passive stress relief by taking favourite food such as drinking alcohol, smoking, drinking coffee, etc.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.4 no.1
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• pp.45-57
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• 1974

This report based on 300 cases of serious diseases in maxillofacial region by radiograms seen at the department of dental radiodontics, infirmary school of dentistry, Kyung Hee University from October 1971 to August 1974. The maxillofacial diseases were analysed upon the following items, such as 1) the frequency of dominant diseases, 2) sex-ratio of male to female, 3) predominant region of diseases, 4) comparison with the age, 5) the incidence of diseases in relative to the individual teeth. The results were obtained as follows. 1) Among the total of 300 cases of the patients, the frequency of dominant diseases of patients were fractures of facial bone (44.3±2.87%), inflammatory diseases (22.7±2.39%), cysts (11.1±1.62%), tumors (10.7±1.77%), maxillary sinusitis (7.9±1.56%), temporomandibular joint disorders(3.3±1.05%) in the order. 2) The ex-ratio of male to female in occurence of jaw fractures were 7.3:1, temporomandibular joint disorders were 2.1:1, inflammatory diseases were 1.8:1, maxillary sinusitis were 1.7:1, but tumors were equal to 1:1, while cysts were 1:1.2 in sex difference. 3) The predominant region of mandibular fractures were symphysis(17.3±3.27%), canine region (15.0±3.09%), and angle region (14.3:±3.04%) in the order. Inflammatory diseases were occured frequently in mandible and it's left side were a little dominant. Odontogenic cysts were observed frequently in maxilla, but regardless of right and left. Carcinomas were involved most frequently in maxilla, while sarcomas and ameloblastomas in mandible. Frequency of the maxillary sinusitis were dominant right side and molar area, also temporomandibular joint disorders were right side. 4) To study comparison with the age jaw fractures showed the highest ratio at the 2nd decade(32.3±4.06%), and 3rd decade (27.8±3.89%), 4th decade (19.6±3.44%), 6th decade (9.0±2.47%), 5th decade(6.0±2.06%), 1st decade (5.3±1.95%) in the order. But 7th decade were not involved entirely. Frequency of the inflammatory diseases were the highest in the age group of 3rd decade (28.0±5.44%), and those of cysts were 5th decade (24.2±7.22%), temporomandibular joint disorders were 3rd decade (60.0±15.49%). Tumors were occured frequently over the 4th decade especially malignint tumors over the 5th decade, but maxillary sinusitis were rearless of age except for 2nd decade. 5) About the incidence of diseases in relative to individual teeth, fractures of facial bone were most frequently involved the maxillary and mandibular anterior teeth, and mandibular 3rd molar region. Cysts were maxillary anterior region inflammatory diseases were mandibular molar region maxillary sinusitis were maxillary 1st molar, region but tumors were regardless of individual teeth.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.72-77
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• 2002

In this paper, a simple method to measure the residual stress in microstructure is presented. In order to find the residual stress in micro-machined beam, the first natural frequency of the beam that has the residual stress inside is analyzed using Rayleigh's energy method. Micro gold electroplated structure is fabricated by surface micro-machining process including electroplating. The made structure is an approximate shape of clamped-clamped beam and its 1 st natural frequency is measured by resonance method. For the better estimation of the residual stress, an equivalent length of micro-fabricated beam to ideal beam is calculated by FEM. The residual stress was estimated from the equivalent length and the measured natural frequency. It was found that a tensile stress was residue in the micro beam structure.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1193-1195
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• 2002

This paper presents Active-clamp Class-E high frequency resonant inverter with single-stage. The proposed circuit is integrated Active-c class-E circuit to boost converter with the funct power factor correction. Boost converter is opera positive and negative half cycle respectively at frequency(60Hz), operating in Discontinuous Con Mode(DCM) of boost converter performs high p factor. By adding active-clamp circuit in Cl inverter, main switch of inverter part is operat only ZVS(Zero Voltage Switch), but also reduce switching voltage stress of main switch. Simulation result using Psim4.1 show that the p prove the validity of theoretical analysis. This proposed inverter will be able to be pract used as a power supply in various fields are ind heating applications, DC-DC converter etc.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.195-200
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• 2000

In order to find a residual stress in the micro-machined beam, first natural frequency of the beam that has the residual stress inside is analyzed using the Rayleigh's energy method. Micro gold electroplated structure is fabricated by surface micro-machining process. The made structure is clamped-clamped beam and its 1st natural frequency is measured by resonance method. For the better estimation of the residual stress, an equivalent length of micro-machined beam to ideal beam is calculated by FEM. The residual stress is estimated from the equivalent length and the measured natural frequency.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.12
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• pp.737-740
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• 2005

This paper describes the possibility of evaluating and classifying arthritic pathology using the acoustical analysis of knee joint sound. Six normal subjects and 11 patients with knee problems were enrolled. Patients were divided into the 1st patient group which required an orthopeadic surgery and the 2nd patient group of osteoarthritis. During sitting and standing periods, subjects' active knee flexion and extension were monitored. Fundamental frequency, mean amplitude of pitch, jitter and shimmer were analyzed according to the position. The results demonstrate that the values of fundamental frequency, jitter and shimmer of the 2nd patient group were larger than others and changed unstably. The values of the standing position were larger than the sitting position.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.996-999
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• 2010

Aluminium extruded panel is the most important element for sound insulation in a express train. However, comparing with the flat plate with the same weight, the extruded panel shows remarkably low sound transmission loss above the 1st local resonance frequency, which is determined by the dimension of the core structure. Preceding study showed the possibility of the improvement of sound insulation performance by properly designing the core dimension. By the proper core design, local resonance frequency shifts to higher frequency region without any reduction of bending or torsional strength and without any weight increase. Based upon this result, this study investigates in detail the design modification of the core structure of the aluminium extruded panel used in a express train under development, in aspect of sound insulation. Design result is compared with those of other developed models.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.848-850
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• 1997

A control method of UPFC (Unified Power Flow Controller) to reduce low frequency oscillation is proposed. UPFC is modelled by voltage source, which magnitude and phase angle can be controlled. Because there needs some time to change to desired value, d-axis voltage and Q-axis voltage is modeled by 1st order delay. LQG(Linear Quadratic Gaussian) is used. It is shown that low frequency can be damped by control of UPFC effectively.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2530-2532
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• 1998

Micro gold electroplating structure is fabricated by surface micromachining process. The made structure is clamped-clamped beam and its 1st natural frequency is measured by resonance method. In order to find residual stress, first natural frequency of beam which has tensile stress inside is analysed using Rayleigh's method. Elastic modulus and residual stress are estimated from the measured natural frequency.