• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.551-555
• /
• 2004

The two-transformer full bridge (TTFB) PWM converter has two transformers which act as the output inductor as well as the main transformer, i.e. as the forward and the flyback transformer. Although the doubled leakage inductor of the TTFB makes it easier to achieve the zero-voltage switching (ZVS) of the lagging leg switch along the wide load range, it instigates a serious voltage ringing in the secondary rectifier diodes, which would require the dissipative snubber circuit, cause the serious power dissipation, and increase the voltage stress across those diodes. To overcome these problems, a, new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped on a half the output voltage $(V_o/2)$ or the output voltage $(V_o)$. Therefore, no dissipative snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. The operations, analysis and design consideration of proposed converter are presented in this paper. To verify the validity of the proposed converter, experimental results from a 425W, 385-170Vdc prototype for the plasma display panel (PDP) sustaining power module (PSPM) are presented.

• The Journal of Information Systems
• /
• v.26 no.2
• /
• pp.105-121
• /
• 2017

Purpose It is a major goal to improve the product yields during production operations in the manufacturing industry. Therefore, factory is trying to keep the good quality materials and proper production resources, also find the proper condition of facilities and manufacturing environment for yields improvement. Design/methodology/approach We propose the hybrid framework to analyze to dataset extracted from MES. Those data is about the alarm information generated from equipment, both measurement and equipment process value from production and cycle/pitch time measured from production data these covered products during production. We adapt a data warehousing techniques for organizing dataset, a logistic regression for finding out the significant factors, and a association analysis for drawing the rules which affect the product yields. And then we validate the framework by applying the real data generated from the discrete process in secondary cell battery manufacturing. Findings This paper deals with challenges to apply the full potential of modeling and simulation within CPPS(Cyber-Physical Production System) and Smart Factory implementation. The framework is being applied in one of the most advanced and complex industrial sectors like semiconductor, display, and automotive industry.

• Journal of Korean Foot and Ankle Society
• /
• v.6 no.1
• /
• pp.15-20
• /
• 2002

Authors studied 24 cases in 18 patients with the hallux valgus deformity treated by Reverdin osteotomy at Department of Orthopaedic Surgery, Wallace Memorial Baptist Hospital from January 1995 to December 1999. Reverdin osteotomy is one of the distal metatarsal osteotomies in the treatment of hallux valgus in adults. We performed Reverdin osteotomy on 24 cases (18 patients) for painful hallux valgus associated with an increased hallux valgus angle (> 35degrees) and first-second intermetatarsal angle(>13 degrees). The results were as follows. 1. The average first-second intermetatarsal angle was 16.8 degrees and average valgus angle was 37.3 degrees, preoperatively. they were corrected to 7.8 degrees and 12 degrees respectively. 2. The metatarsalgia of the great toe was subsided in all cases and they were satisfied with the result of their operations in respect to cosmetically and functionally. Avascular necrosis of capital fragment, nonunion, and dorsal angulation were not developed in any case. But one case had superficial wound infection and delayed union, presumably due to secondary infection.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.266-269
• /
• 1999

Several power factor correction(PFC) circuits are presented to achieve high PF electronic ballast for both voltage-fed and current-fed electronic ballast. The proposed PFC circuits use valley-fill(VF) type DC-link stages modified from the conventional VF circuit to adopt the charge pumping method for PFC operations during the valley intervals. In voltage-fed ballast, charge pump capacitors are connected with the resonant capacitors. In current-fed type, the charge pump capacitors are connected with the additional secondary-side of the power transformer. The measured PF and THD are higher than 0.99 and 15% for all proposed PFC circuits. The lamp current CF is also acceptable in the proposed circuits. The proposed circuit is suitable for implementing cost-effective electronic ballast.

• Journal of Environmental Science International
• /
• v.20 no.6
• /
• pp.767-773
• /
• 2011

The objectives of this research are to investigate the proper coagulation conditions which are a type and doses of coagulants, mixing conditions (velocity gradients and mixing times), pH and so on through Jar-test, to evaluate the flux variations, permeate, backwashing according to characteristics of pretreatment of the wastewater by means of MF membranes for river maintenance water reuse. The effluent water from B-city K-sewage treatment plant are used for this research. Turbidity and suspended solids(SS) are 14.2 NTU and 10.4 mg/L respectively. This condition causes fouling for membrane process. The flux decline could be reduced when coagulation pretreatment was carried out. Optimal coagulations PAC which are commonly used in the sewage treatment plant was observed in this research. The results indicate that an optimal coagulation dose and pH are 80 ppm and pH of 7 respectively, but coagulation efficiency was lower at strong acid or strong base. Results showed that continuous and steady operations in membrane separation process by means of the effective removal of organic matter and turbidity with coagulation pretreatment of sewage secondary effluent were achieved.

• Archives of Craniofacial Surgery
• /
• v.13 no.2
• /
• pp.143-146
• /
• 2012

Purpose: The typical reconstructive option for the nasal tip is paramedian forehead flap. However, the forehead flap is too bulky for nasal tip reconstruction and does not look natural, and therefore, secondary operations for debulking are required. Methods: We treated a 46-year-old woman who suffered from a nose tip soft tissue defect using a modified paramedian forehead flap. The flap was elevated from the hair line of the forehead and had 3-layered structure. The distal part included skin and subcutaneous tissue, the middle part included frontalis muscle, and the proximal part had periosteum. Results: The nasal tip was not bulky and looked natural in terms of height, shape, and had 3-dimensional structure without debulking procedure. The patient was satisfied with the outcome. Conclusion: The authors' modified paramedian forehead flap may be a useful option for the treatment of nasal tip, columella, and alar defects. With these modifications, the paramedian forehead flap can provide an aesthetically acceptable nasal tip appearance without debulking.

• Journal of Environmental Health Sciences
• /
• v.28 no.4
• /
• pp.12-16
• /
• 2002

Workers' exposure to lead particles with diverse characteristics was assessed using personal cascade impactors in four different industries. Correlation analyses found that total airborne lead (PbA) concentrations could not explain the variation on MMAD of lead particles. From regression analysis, the concentrations of lead particles smaller than 1 um in AD were found to rise very slowly with increases in total PbA. They rarely contributed more than 50 ㎍/㎥ of total PbA over the range of 5.6-7,740 ㎍/㎥ although there are a few high values greater than 100 ㎍/㎥ while respirable lead concentrations significantly increased with increasing total PbA concentrations. In the secondary smelting and radiator manufacturing industries requiring high temperatures, the average fraction of respirable concentration in total PbA was 43.3% and 48.9%, respectively, which indicated an important contribution to the total PbA. In lead powder and battery manufacturing, it was less than 27%. Our study results concluded that workers' exposure to lead particles with diverse characteristics might not be effectively monitored by the current total PbA sampling alone. To protect workers exposed to different sizes of lead particles generated in many operations, an occupational standard for respirable lead particles should be added to the current total lead standard.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.5
• /
• pp.81-90
• /
• 2020

This study investigates the nexus between the level of Corporate Social Responsibility Disclosures (CSRD) and Risk of Bankruptcy of companies that are listing in the Stock Exchanges of Vietnam. To investigate that relationship, this study collected secondary data from annual audited financial statements from 2014 to 2018 of listing companies. Applying two different regression models with two dependent variables and six independent and control variables, we find out that Vietnamese firms with higher level of CSRD performance can rapidly reduce their risk of bankruptcy. This phenomenon happens in the current year and in the coming years in all firms in the research sample. This result may be that the disclosures of social responsibility information can bring financial and non-financial benefits to the firms. In addition, the results also point out that there is a difference in risk of bankruptcy between the group of companies, which discloses and the one which does not disclose corporate social responsibility on their annual reports. This might be from the effects of various factors such as business size, financial leverage, market to book ratio, return on assets, cash flow from operations, etc. Our research results can be applied to other firms in Vietnam and in other similar jurisdictions.

• Archives of Plastic Surgery
• /
• v.32 no.1
• /
• pp.37-42
• /
• 2005

The human nose is located in the center of the face and it's cosmetic importance is high. The contour of the nasal dorsum and side walls play a major role in the shaping of the nose, and even a slight distortion may results in significant variance of the human facies. However, in the case of patients with wide nasal bone, augmention rhinoplasty can make nasal planes look wide, resulting in bulbous appearing noses or lateral borders of the nasal implant may be visible after the surgery making the final cosmetic results unsatisfactory. To solve such problems, from march, 1999 to march, 2004, the authors have performed augmention rhinoplasty in 36 patients. The cause of operations were as follows: flat nose 20, hump nose 5, deviated nose 4, secondary rhinoplasty 7. Paramedian osteotomy was performed at a distance that was the same as the width of the implant from the midline(5 mm + 5 mm). To prevent it from connecting to the roof at the lateral osteotomy line, intentional green stick fracture of the roof was performed. Agumentation rhinoplasty was done with either Silicone or Gortex and ear cartilage as a supplement. The follow up period was 2 weeks to 13 months with an average of 5.5 months. There were no infections and postoperative bleeding. As a result, the nose was augmented higher and narrower than before which we and the patient both found highly satisfactory.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.9
• /
• pp.2037-2051
• /
• 2012

Cognitive radio (CR) is envisioned as a promising paradigm of exploiting intelligence for enhancing efficiency of underutilized spectrum bands. In CR, the main concern is to reliably sense the presence of primary users (PUs) to attain protection against harmful interference caused by potential spectrum access of secondary users (SUs). In this paper, evolutionary algorithms, namely, particle swarm optimization (PSO) and genetic algorithm (GA) are proposed to minimize the total sensing decision error at the common soft data fusion (SDF) centre of a structurally-centralized cognitive radio network (CRN). Using these techniques, evolutionary operations are invoked to optimize the weighting coefficients applied on the sensing measurement components received from multiple cooperative SUs. The proposed methods are compared with each other as well as with other conventional deterministic algorithms such as maximal ratio combining (MRC) and equal gain combining (EGC). Computer simulations confirm the superiority of the PSO-based scheme over the GA-based and other conventional MRC and EGC schemes in terms of detection performance. In addition, the PSO-based scheme also shows promising convergence performance as compared to the GA-based scheme. This makes PSO an adequate solution to meet real-time requirements.