• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.5
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• pp.248-254
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• 2001

The traction power demand highly varies with time and train positions and the traction load is a large-capacity current at single phase converted from 3-phase power system. Subsequently, each phase current converted from 3-phase power system cannot be maintained in balance any longer and thus the traction load can bring about imbalance in three-phase voltage. Therefore, the exact assessment of voltage unbalance must be carried out preferentially as well as load forecast at stages of designing and planning for electric railway system. The evaluation of unbalance voltage in areas, such as electric railway depots should be a prerequisite with more accuracy. The conventional researches on voltage unbalance have dealt with connection schemes of the transformers used in ac AT-fed electric railroads system and induced formulas to briefly evaluate voltage unbalance in the system(3). These formulas are still being used widely due to their easy applicabilities on voltage unbalance evaluation. Meanwhile, they don't take into account detailed characteristics of ac AT-fed electric railroads system, being founded on some assumptions. Accordingly. accuracy still remains in question. This paper proposes a new method to more effectively estimate voltage unbalance index. In this method, numerous diverted circuits in electric railway depots are categorized in three components and each component is defined as a two-port network model. The equivalent circuit for the entire power supply system is also described into a two-port network model by making parallel and/or series connections of these components. Efficiency and accuracy in voltage unbalance calculation as well can be promoted by simplifying the circuits into two-port network models.

• Human Ecology Research
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• v.56 no.5
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• pp.417-424
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• 2018

The use stage of a textile product impacts sustainability more significantly than other stages of the product's life cycle due to repeated washing and drying. This study determines efficient washing conditions, with high detergency, to reduce energy consumption from excessive washing and improve the washing process sustainability. Detergency was measured at various washing temperatures ($20^{\circ}C$, $40^{\circ}C$, and $60^{\circ}C$) and time (10 min, 20 min, and 30 min) using standardized soiled fabrics, i.e., 100% cotton, polyester/cotton (65%/35%), and 100% polyester woven fabric soiled with pigment/sebum, carbon black/mineral oil, soot/mineral oil, cocoa, blood, and red wine. Detergency at the washing condition of $20^{\circ}C$ and 30 min was higher than that at $40^{\circ}C$ and 10 min. In addition, detergency at the condition of $40^{\circ}C$ and 30 min was also higher than that at $60^{\circ}C$ and 10 minutes. This may be because a reduced washing effect at low washing temperatures was complemented by increased mechanical action over a long time. Further, washing temperature and time, with the same detergency, differed based on the type of fiber and soil. Also, the influence of a detergent on the detergency depends on the type of soil. The results suggest that energy and detergent have been consumed more than necessary in actual laundry. According to each type of fiber and soil, washing conditions designed to reduce the energy consumption of the washing process while maintaining the same detergency, were determined.

• Archives of Plastic Surgery
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• v.34 no.2
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• pp.149-155
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• 2007

Purpose: This study was to investigate how the heparin, which has been known to induce neovascularization by MMP in the infarcted tissue of the myocardium, had influence on the expression of mRNA of MMP 1,2,9 of the skin wound of rat. Methods: Full depth skin wounds were created on the dorsum of Sprague-Dawley 60 rats. The experimental rats were divided into two groups according to the concentration of heparin($100{\mu}g/ml$ in 20, $300{\mu}g/ml$ in 20). Heparin soaked gelatin sponges in different concentration were inserted into the pocket of experimental rats and the wounds were closed. Normal saline soaked gelatin sponges were used in control rats. Wounds were harvested at 48 and 72 hours after closure. We performed histologic study in H-E stain. RNA was isolated from the harvested tissue and then real time polymerase chain reaction was performed to determine the gene expression of MMP-1,2,9. Results: We observed that inflammatory cell decreased in heparin soaked group and heparin increased the expression of MMP-1,9 mRNA of dorsal wound of rat at 72 hours (p < 0.05). Conclusion: This result suggest that heparin may be used inducing another factor inducing scarless wound healing by increasing MMP.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.351-358
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• 2011

Purpose: The inflammatory phase is considered an integral part of adult wound healing, but fetal wound healing studies have shown scarless healing results in the absence of the inflammation process. The COX-2 pathway is an essential component of inflammation. The purpose of this study is to identify the effect of a topical selective COX-2 inhibitor on inflammation in rabbit skin wound healing and scarring. Methods: Full-thickness wounds were made on 6 New Zealand rabbits' ears. Topical 5% celecoxib + vehicle (experimental tissue) and vehicle only (controlled tissue) were applied daily for 14d on each side of the ears. Scar samples were harvested at 2 wks, 4 wks, and 8 wks after the wounding. Each sample was stained with hematoxylin and eosin and the Masson's trichrome stain to evaluate inflammation and scar formation. Results: Histological analysis demonstrated a significant reduction of inflammation, neovascularization, and scar elevation in the experimental tissue as compared to the control. Additionally, experimental tissue exhibited faster improvement of collagen organization similar to that of normal tissue. Conclusion: This study suggests that the topical application of a selective COX-2 inhibitor on a rabbit ear wound resulted in decreased inflammation and had a positive effect on the reduction of scar formation.

• Archives of Plastic Surgery
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• v.38 no.5
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• pp.585-589
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• 2011

Purpose: Microcirculation of diabetic patients is commonly comporomised, regardless of the condition of the macrocirculation. Therefore, direct tissue oxygenation measurement is recommended in determining tissue viability and predicting wound healing potential. This study was designed to determine cut-off value of the tissue oxygenation in predicting wound healing in diabetic foot patients. Methods: This study included 41 feet of 41 diabetic foot patients who were treated in the Diabetic Wound Center of author's institution between January and June, 2009. Main inclusion criteria were type 1 or 2 diabetes and a foot ulcer (duration > 3 weeks) and ulcer area (from 1 $cm^2$ to 4 $cm^2$). Measurements of the area of diabetic foot ulcer were carried out before treatment. Transcutaneous oxygen pressure ($TcpO_2$) was measured at adjacent site of ulcer. The healing wound was defined as complete wound closure within 12 weeks. Results: Average diabetic foot ulcer areas with healing and nonhealing wounds were $2.67{\pm}0.76$ and $2.59{\pm}0.75\;cm^2$, respectively. There was no significant difference in the wound area between the groups. Average foot $TcpO_2$ in healing and nonhealing wounds were $68.56{\pm}23.07$ and $30.98{\pm}16.66$ mmHg, respectively ($p$ <0.01). The rate of healing wound increased as $TcpO_2$ increased. In particular, $TcpO_2$ lower than 40 mmHg and higher than 40 mmHg showed the most significant difference (wound healing rates of 25% and 71%, respectively). Conclusion: Based on the results of the study, the minimal $TcpO_2$ value thought to be required for adequate wound healing in diabetic wounds (cut-off value) is 40 mmHg.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.345-350
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• 2011

Purpose: Although platelet-rich plasma (PRP) potentiate the wound healing activity of adipose-derived stem cells (ADSCs), its effect cannot be sustained for a prolonged period of time due to short duration of action. This led us to design and produce platelet-rich fibrin (PRF), in an effort to develop a tool which lasts longer, and apply it on wound healing. Methods: Two symmetrical skin defects were made on the back of seven nude mice. ADSCs were applied to each wound, combined with either PRP or PRF. The wound area was measured over 14 days. By day 16, the wound was harvested and histologic analysis was performed including counting of the blood vessel. Results: The healing rate was more accelerated in PRP group in the first 5 days (p<0.05). However, PRF group surpassed PRP group after 6 days (p<0.05). The average number of blood vessels observed in the PRF group was $6.53{\pm}0.51$, compared with $5.68{\pm}0.71$ for the PRP group. Conclusion: PRF exerts a slow yet pervasive influence over the two-week course of the wound healing process. Thus, PRF is probably more beneficial for promoting the activity of ADSCs for a sustained period of time.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.523-526
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• 2011

Purpose: The odontogenic sinus and fistulous tracts is the most common draining sinus and fistulous tract of the head and neck region. These are often misdiagnoses by clinicions who are not familiar with cutaneous sinus, since most of patients do not have dental symptoms. Here we present two cases of odontogenic cutaneous sinus tract which have been diagnosed after excision of epidermal cyst. Methods: Two patients who presented with an odontogenic sinus tract draining to the skin at our institusion during the two years were enrolled in this study. We reviewed all the medical records of the patients and literature about odontogenic cutaneous sinus tract. Results: Odontogenic cutaneous sinus tracts of our cases were healed after treatment of periapical odontitis and extraction of the carious tooth. Conclusion: The cutaneous sinus tract of dental origin is well documented condition. But its diagnosis is not always easy unless the clinicians consider the possibility of its dental origin. An understanding of the pathogenesis of odontogenic cutaneous sinus tract will lead to early correct diagnosis and proper treatment without unnecessary surgery.

• Archives of Plastic Surgery
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• v.36 no.5
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• pp.538-542
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• 2009

Purpose: The successful wound healing means the scarless wound with adequate strength. It has been shown in vivo and in vitro that steroid retard the collagen synthesis. We studied the effect of steroid on the wound breaking strength in rats. Methods: 40 Sprague - Dawley rats were evenly assigned to two groups. One group was served as control, the other group was experimental. We made dorsal midline incision and closed the wound. In the experimental group, we medicated methylprednisolone (0.15 mg/g/day) for 1 week. Then, we compared the differences of the breaking strength and microscopic histology between control and experimental group at 2, 4, 6 and 8 week. Results: Up to 4 week, the breaking strength of the experimental group was markedly decreased than that of control group, while at 6 week the strength of experimental group attained to that of control group nearly. In histologic findings, control group demonstrated dense organization of collagen to experimental group at 4th week. Conclusion: In this experiment, steroid significantly inhibited the strength gain in wound at early period of the wound healing process. When using steroid after the surgery or the wound formation, it is desirable to administrate carefully and need thorough wound management to prevent delayed wound healing.

• The Journal of Korean Physical Therapy
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• v.14 no.2
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• pp.234-249
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• 2002

This study was performed, using c-fos and Substance P, to investigate the effect of GaAlAs laser on acute pain model induced by wound in lumbar region's spinal level. The test group was divided into control and experimental group. Control group is shamed group(c-fos and substance P expression after non-irradiation by a GaAlAs laser), The experimental group was divided into two subgroups: one is experimental group I (c-fos expression after irradiation by a GaAlAs laser), and the other is experimental group II (substance P expression after irradiation by a GaAlAs laser). The results of this study were as following: 1. The numbers of c-fos immunoreactive neuron in spinal cord was increased markedly 1 day after wound, and decreased gradually from 1 day to 2 days in wound with GaAlAs laser irradiation. 2. The changes of the average percentages of substance P immunoreactive neurons in spinal cord was increased markedly 1 day after wound, and decreased gradually from 1 day to 2 days in wound with GaAlAs laser irradiation. Therefore, decreasing the changes of c-fos and substance P expression after irradiation by a GaAlAs laser indicates and GaAlAs laser have effect on pain control.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1202-1206
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• 1996

Ebstein's anomaly is an unusual and a rare congenital cardiac malformation but characteristic abnormality of the development of the tricuspid valve, right atrium and ventricle. The characteristic findings are a displaced tricuspid valve with a septal leaflet spiralling into the right ventricle. The surgical correction is variable and are left unsolved problem in surgical treatment of anomaly. Between January 1988 ＆ December 1995, we experienced 11 cases of Ebstein's anomaly and associated cardiac anomalies are ASD, PFO, ASD with VSD. The typically displaced tricuspid valve leaflet was found in all cases. In the NYHA functional classification, three were in class II, seven were in class III, and one was in class IV. Nine patients were operated by tricuspid annuloplasty ＆ plication with Danielson's method and two patients were done by tricuspid valve replacement with plication, and in all cases associated anomaly was corrected. Postoperatively, five patients suffered from complication - low cardiac output syndrome, arrhythmia and wound infection. There was no operative mortality and the postoperative courses were relatively good conditions with more improvement of symptoms.