• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.139-141
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• 2000

High voltage direct current(HVDC) transmission system uses the phase controlled rectifier triggered by means of IPC(individual phase control) or EPC(equidistant pulse control). Most HVDC system has adopted EPC method that can solve the harmonic instability problem of IPC method in weak power system. But EPC has inherent indirect synchronizing problem requiring the closed loop control. This paper presents the new gate pulse generating method for 12-pulse HVDC converter, which combines IPC with EPC. Simulation and test results are presented. The basic concept is that it generates the gating pulse for 12-pulse converter by synthesizing the internal phase reference using the frequency and phase information of a sin91e phase voltage. To ensure the reliability of the external phase input, Potential transformer that detects the phase voltage has redundancy. Using fault detecting algorithm the healthy input is always guaranteed. And the frequency compensation function was reinforced.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.955-961
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• 2002

2.7vol%TiNi/6061 Al composites with TiNi shape memory alloy as reinforcement were fabricated by vacuum hot press. It was investigated by OM, SEM, EPMA and XRD analysis for the behavior of diffusion layer formation on various heat treatment condition. Thickness of diffusion layer was increased proportionally according to heat treatment time. The layer was formed by the mutual diffusion of TiNi and Al. The diffusion rate from TiNi fiber to Al matrix was faster than that of reverse diffusion path. The more diffused layer was formed in Al matrix. The diffusion at interface layer was consisted of $A1_3$Ti, $Al_3$Ni analyzed by EPMA, XRD results.

• Journal of Distribution Science
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• v.12 no.12
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• pp.27-41
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• 2014

Purpose - This study examines various reservation service components that would increase customers' brand attachment and loyalty, while discussing how reservation service components would affect the customer behaviors. Research design, data, and methodology - This study theoretically analyzed the hotel package product reservation system, the customer expectations, the brand attachment, and the brand loyalty, while reviewing previous studies. Results - This study analyzed the distribution channels of the hotel package products from various angles and, as for more extensive research, the study explained the different results caused by each different reservation system type that may be preferred by each individual customer. Conclusions - It was confirmed that, of the hotel reservation service components, the convenience factors, the reliability factors, the information factors, and the other factors other than the human factors, have a significant influence on the customer expectations. Further, the study also revealed that the customer expectation has an important effect on the brand attachment. In addition, the study improved the prevailing understanding on the relation between the brand attachment and the brand loyalty.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.346-349
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• 2002

Ferroelectric $Bi_{4-x}Nd_{x}Ti_{3}O_{12}(BNdT)$ thin films with the composition(x=0.75) were prepared on $Pt/Ti/SiO_{2}/Si(100)$ substrate by metal-organic deposition. The films were annealed by various temperatures from 550 to $650^{\circ}C$ and then the electrical and structural characteristics of BNdT films were investigated for the application of FRAM. Electrical properties such as dielectirc constant, 2Pr and capacitance were quite dependent on the thermal heat treatment. The measured 2Pr value on the BNdT capacitor annealed at $650^{\circ}C$ was $56{\mu}C/cm^{2}$ at an applied voltage of 5V. In fatigue characteristics value remained costant up to $8{\times}10^{10}$ read/write switching cycles at a frequency of 1Mhz regardless of annealing temperatures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.3
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• pp.281-287
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• 2012

The internal oxide scale of twelve superheater and reheater tubes were tested which were serviced for 30,000~120,000 hours in thermal power plants. The oxide scale was formed in three layers. The Cr-rich area was observed beneath the original metal surface. The hematite ($Fe_2O_3$) phase was formed on the outer surface. The intermediate layer was magnetite ($Fe_3O_4$). The thickness of Cr-rich layer was about half of the total scale. All layers grew during the operation hour of the plant. The thickness of thickest scale was 0.2mm in superheater tubes. This can increase the tube metal temperature about $7^{\circ}C$ more than initial state. $7^{\circ}C$ tube metal temperature can reduce tube life about 30%, but the boiler tube's design margin is big enough therefore it has been analyzed that it would not effect on the life span.

• The Journal of the Korean bone and joint tumor society
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• v.3 no.2
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• pp.131-136
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• 1997

Although chondrosarcoma is a common primary malignant bone tumor, its occurrence in the spine is very rare. It is also well known that even after complete removal of chondrosarcoma in bone, not a few recurrence is possible. Surgical cure of a spinal chondrosarcoma is even more difficult because total excision of chondrosarcoma is usually impossible in the spine. No patients with spinal chondrosarcoma surviving more than 18 years has been reported in literature. We are reporting one patient(32 year old housewife) with chondrosarcoma at the $12^{th}$ thoracic spine which was treated with complete corpectomy of the $12^{th}$ thoracic vertebral body and rib and cancellous bone graft fixed with plating. She was followed for more than 3 years without local recurrence or distant metastasis.

• Journal of Oral Medicine and Pain
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• v.19 no.1
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• pp.9-15
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• 1994

This experiment was performed to confirm the hypothesis that LLLT had biostimulation effect for all kinds of cells and there would be differences in the growth of cells among different types of pulsed laser. 360 samples were used in this study. The samples were randomly divided in 6 groups according to the pulse type : quasi continuous type (CW), pulse 1(P1), pulse 7(P7), pulse 9(P9), pulse 15(P15) and shame-irradiated control(Co) groups. Energy fluences of all experimental groups, P1, P7, P9, P15 and CW were 2.12, 2.12, 6.37, 57.32 and 31.85 mj/cm2 respectively. All samples were irradiated for every 1 minute at 0, 12, 24, 36, 48 and 60 hours. Ten samples of each group were sacrificed at 0 and every 12 hours and then the optical density of all samples was measured with the spectrophotometer. As a result, some types of pulses showed significant differences among groups. The increase of cells were markedly stimulated with laser irradiation in P7 and P9 groups, while inhibited in CW, P1, and P15 groups compared with control group. It is therefore, suggested that specific laser pulse should be recommanded to have the biostimulation effects on the specific tissue or cells, although the biostimulation effect is does dependant.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.383-387
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• 2009

Multi-crystalline silicon surface etching without grain-boundary delineation is a challenging task for the fabrication of high efficiency solar cell. The use of sodium hydroxide - sodium hypochlorite (NaOH40% + NaOCl 12%) solution for texturing multi-crystalline silicon wafer surface in solar cell fabrication line is reported in this article. in light current-voltage results, the cells etched in NaOH 40% + NaOCl 12% = 1:2 exhibited higher short circuit current and open circuit voltage than those of the cells etched in NaOH 40% + NaOCl 12% = 1:1 solution. we have obtained 15.19% conversion efficiency in large area(156cm2) multi-Si solar cells etched in NaOH 40% + NaOCl 12% = 1:1 solution.

• Development and Reproduction
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• v.24 no.3
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• pp.167-176
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• 2020

The fat pad defined as the epididymal fat is located at the head part of the epididymis. However, another fat mass is present near the caudal epididymis, named tail epididymal fat. The present research was focused to determine the expression of adipocyte-associated molecules in the mouse tail epididymal fat at different postnatal ages, including 2, 5, 8, and 12 months of age. The quantitative real-time PCR analysis showed continuous increases of expression levels of delta like non-canonical Notch ligand 1, leptin, and resistin as postnatally aged. The transcript level of peroxisome proliferator-activated receptor gamma was the highest at 5 months of age, remaining at a steady level until 12 months of age. Expression levels of fatty acid binding protein 4, leptin, and adiponectin were significantly increased until 8 months of age, persisting the level at 12 months of age. The transcript level of fatty acid synthase was significantly increased at 8 months of age, without a further change of the level at 12 months of age. These findings exhibited the expression of adipocyte-associated genes which were also detected at the ordinary epididymal fat pad. However, expression patterns of these genes in the tail epididymal fat are different with those in the distal and proximal epididymal fat, suggesting distinct characteristics and/or functions of the tail epididymal fat.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.12
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• pp.986-993
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• 2002

The equations of motion for an automated guide-way transit(AGT) system running on a path with roughness have been derived to investigate dynamic responses and wheel loads of moving vehicles of the AGT system. A vehicle of the AGT system is idealized as three-dimensional model with 11 degree-of-freedom. The computer program is developed to solve the dynamic equations, and anlatical results are verified by comparing the results with experimental oness. Parametric studies are carried out to investigate the dynamic responses of an AGT vehicle according to vehicle speeds, surface roughness, damping and stiffness of suspension systems. The parametric study demonstrates that amplitudes of dynamic responses and the wheel loads have a tendency to increase according to travel speeds, the stiffness of suspension system and surface roughness. On the other hand. those amplitudes tend to decrease according to increase of damping of the suspension system.