• Journal of Power Electronics
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• v.9 no.2
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• pp.232-242
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• 2009

In this paper, a matrix converter with improved low frequency output performance is proposed by achieving a one-step commutation owing to a general commutation circuit applicable to n-phase to m-phase matrix converters. The commutation circuit consists of simple resister and capacitor components, leading to a very stable, reliable and robust operation. Also, it requires no extra sensing information to achieve commutation, allowing for a one-step commutation like a conventional dead time commutation. With the dead time commutation strategy applied, the distortion caused by commutation delay is analyzed and compensated, therefore leading to better output linear behavior. In this paper, detailed commutation procedures of the R-C commutation circuit are analyzed. A selection of specific semiconductor switches and commutation circuit components is also provided. Finally, the effectiveness of the proposed commutation method is verified through a two-phase to single-phase matrix converter and the feasibility of the compensation approach is shown by an open loop space vector modulated three-phase matrix converter with a passive load.

• Journal of the Korean Society of Costume
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• v.60 no.4
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• pp.98-112
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• 2010

This study is on the 18th-century man's clothing excavated from Mr. Kim(1683-1766)'s tomb in Cheongju, Chungbuk in 2003. There are more than 100 pieces of excavated costumes from the tomb of Won-taek Kim. The excavated costumes have the value of genuine materials. Among them, 36 garments in good condition were investigated. As a result, there are several kinds of the excavated coats with different sizes, depending on the type of coats-Simui(深衣), Danryeong(團領), Sagyusam(四揆衫), Daechang, jungchimak(中赤莫), and Sochangui. These different-size coats reveal the degree of ritual; the length of the ritual costume is longer than that of the daily one. We can see two kinds (large and small) of coats, jackets, and pants. The large-size clothing is for the dead, the small size one as daily clothing was used for filling the empty space of the coffin. Among the excavated clothing from Mr. Kim's tomb, clothing for the dead(shroud) is bigger than man's daily costume. Concerning the form, color, and materials of the costumes, clothing for the dead is similar to daily clothing, while there is the difference in their size. The oversized costumes of coats, jackets, and pants are also different in size, matching the structure of clothing.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.126-133
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• 2022

This study proposes a suppression of zero sequence current (ZSC), which is caused by zero sequence voltage (ZSV) for a dual two-level inverter with single DC bus. Large output voltages enable the dual inverter with single DC bus to improve a system efficiency compared with single inverter. However, the structure of dual inverter with single DC bus inevitably generates ZSC, which reduces the system efficiency and causes a current ripple. ZSV is also produced by dead time, and its magnitude is determined by the DC bus and current direction. This study presents a novel space vector modulation method that allows the instantaneous suppression of ZSC. Based on a condition where a switching period is twice a sampling (control) period, the proposed control method is implemented by injecting the offset voltage at the primary inverter. This offset voltage is injected in half of the switching period to suppress the ZSC. Simulation and experiments are used to compare the proposed and conventional methods to determine the ZSC suppression performance.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.169-175
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• 1998

Background: Heliox is known to decrease $PaCO_2$ in patients with increased airway resistance by increasing minute ventilation and reducing work of breathing(WOB). Besides these effect, heliox is expected to decrease functional anatomic dead space owing to improvement of peak expiratory flow rate(PEFR) and enhancement of gas distribution. We investigated whether heliox can decrease $PaCO_2$ even at the same minute ventilation (VE) and WOB with $N_2-O_2$ to speculate the effect of the heliox on the anatomic dead space. Material and Method: The subjects were 8 mechanically ventilated patients with asthma or upper airway obstruction(M : F=5 : 3, $68{\pm}10$years) who were under neuromuscular paralysis. The study was consisted of three 15-minutes phases: basal $N_2-O_2$ heliox and washout Heliox was administered via the low pressure inlet of servo 900C, and respiratory parameters were measured by pulmonary monitor(CP-100 pulmonary monitor, Bicore, Irvine, CA, USA). To obtain the same tidal volume(Vt) in heliox phase, the Vt on monitor was adjusted by the factor of relative flow rate of heliox to $N_2-O_2$. Dead space was calculated by Bohr equation. Results: 1) Vt, VE, peak inspiratory pressure(PIP) and peak inspiratory flow rate(PIFR) were not different between $N_2-O_2$ and heliox. 2) PEFR was higher on heliox($0.52{\pm}0.19$L/sec) than $N_2-O_2$($0.44{\pm}0.13$L/sec)(p=0.024). 3) $PaCO_2$(mmHg) were decreased with heliox($56.1{\pm}14.1$) compared to $N_2-O_2$($60.5{\pm}15.9$)(p=0.027). 4) Dead space ventilation(%) were decreased with heliox($73{\pm}9$ with $N_2-O_2$ and $71{\pm}10$ with heliox)(p=0.026). Conclusion: Heliox decreased $PaCO_2$ even at the same VE and WOB with $N_2-O_2$, and the effect was considered to be related with the reduction of anatomic dead space.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.703-708
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• 2011

In this paper, most of the church except for a large church has accommodated many audience to install a balcony floor in a small space. therefore, dead zone and dislocated sound image localization is made due to this under-balcony seats. This paper propose that the problems of dead zone and dislocated sound image localization could be solved using computer simulation in the view of practical side. The economical computer simulation tool, Mapp online that can be found easily was used to the specified church. Installation a sub speaker for dead zone and -10 dB power control of the sub speaker to main speaker power for dislocated sound image localization was proposed. Computer simulation result shows that the value of definition for area was improved from "Normal" to "Very Good" which means about 52% improvement.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.4
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• pp.499-507
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• 1994

The aim of this experiment is to compare the healing process of extraction sockets after immediate implant placement with those using autogenous bone grafts and guided tissue regeneration with Gore-Tex. The first lower premolars and the second premolars of six experimental dogs were extracted and Stryker fin type implants were placed into the extraction sockets immediately after extraction. In the control group, any graft materials were'not used and the dead space around implants was left in itself and covered with only periosteum. In the experimental group A, implants were covered with Gore tex without any bone grafts, and in the experimental group B, the dead space around implants was filled with the bone chips gained from drilling procedure. Each experimental dogs were sacrificed at the 1st, 2nd, 3rd, 6th, and 8th week and the specimens were observed by gross examination, radiological examination, and light microscopic examination. The following results were obtained. 1. Well healed soft tissue and no mobility of the implants were observed in control and two experimental groups. 2. In the radiogical examination, radiopacity around implants had been increased gradually. 3. In the microscopic examination, there were good healing process and active new bone formation in both in the experimental groups, Especially the more amount of new bone formation occurred in the experimental group B using bone chips. 4. Bone chip grafts and guided tissue regeneration (GTR) using Gore-Tex may be one of the successful methods in the immediate implantation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.5
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• pp.425-429
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• 2011

Bone grafts are becoming increasingly common in oral and maxillofacial surgery to improve bone healing procedures. Bovine bone as a xenograft is a representative osteoconductor and space filler; however, sometimes complications, such as infection and wound dehiscence are encountered with its use. We report the result of an eight-year follow-up of a xenograft case and processing methods of inorganic bovine bone along with a review of the literature. Xenograft ($LUBBOC^{(R)}$) was used in a cyst enucleation site of the maxilla, as a bone substitute and space filler. Inflammation and infection were defined several times as lack of osseous contact between the graft and host bone, caused by remodeling failure over an eight-year period. Pathologic findings of the xenograft revealed dead bony trabeculae with inflamed fibrous tissue and actinomycosis.

• 한국공간정보시스템학회:학술대회논문집
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• 2003.11a
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• pp.159-162
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• 2003

In this paper, to find probable collision positions between moving object and terrain in 3D space efficiently, we use a model, similar to Ray Tracing, which finds the triangles intersected by a directed line segment from a large amount of triangles. We try to reduce dead space as much as possible to find candidate triangles intersected by a directed line segment than previous work's. A new modified octree, LBV-Octree(Least Bounding Voxel Octree), is proposed, and we have a ray tracing with it. In the experiment, ray tracing with LBV-Octree provides $5%{\sim}11%$ better performance than with classical octree.

• Journal of Biosystems Engineering
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• v.27 no.1
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• pp.33-38
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• 2002

The indicated power of Stirling engine was affected by the heat exchange effectiveness of the regenerator. The temperature difference of working fluid between the expansion and the compression space of Stilting engine depends on the heat exchange effectiveness of the regenerator. The influence of the temperature ratio of expansion space to compression space of Stirling engine on the indicated power was analyzed by using Schmidt analysis in this study. In the Stirring engine, as the temperature ratio increased, the indicated power generally decreased. Therefor, it is necessary to develope the regenerator of high effectiveness. The actual indicated power was shown 64.9 percent of the predicted indicated power in maximum and 47.2 percent of that in minimum due to increased dead volume of engine, the loss of flow friction and heat transfer in the regenerator.

• Journal of the Korean housing association
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• v.18 no.3
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• pp.51-61
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• 2007

This study is aimed to provide a guide for PC use space in apartment. To achieve this, a design about PC use space which was considered adequate location, area, form was suggested. As methods of the study, survey research method and case study. The survey was taken by five hundred-eighty-nine people who used PCs in apartment from May 2005 to July 2005 in JeJu Special Self-governing Province for an analysis of data. The results of the survey were showed PC use space situation and furnitures layout patterns. The case was classified by unit plans of size, and it showed design example of PC use space. In types of $61{\sim}69$ square meters ($m^2$), PC use space was located in dead-space in the residence with minimum scale, because of $61{\sim}69$ square meters types are smaller than the other types. In types $100{\sim}129$ square meters, PC use space which was divided with a partition panel was located in the livingroom expanding the room space to the balcony. In types of 130 square meters, PC use space was located in the room of sons or daughters which was arranged with other furniture. The adequate area of PC use space is $1.4{\sim}2.2$ square meters, and it should take into account furniture size and human active sphere. And PC use space of form should consider traffic line, personal space and privacy. Besides it is required of ergonomic design in chair, table in its scale. And it is necessary development of systematic furniture for PC use space.