• Archives of Plastic Surgery
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• 제33권5호
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• pp.606-611
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• 2006

Purpose: Animal models of a chronic wound are yet to be fully developed, and animal studies on this subject has yet to take place. The purpose of this study is to create the foundation for research on chronic wound healing based on a swine model, the most similar to that of a human. Methods: Three female 2-3 month old 'yolkshires' were used. Total of eight full thickness skin defects, $6{\times}3cm$ sized, were created on the back of each pigs. Three groups were created for comparison; Group I (n=4) was left as they were after full skin thickness excision, while the excised tissues of Group II (n=3) were turned inside out and sutured so that the epidermis would come in contact with the fascia. Group III (n=3) were excised full skin thickness in depth and silicone blocks were implanted in them. Dressing was not practised so that the wounds would be vulnerable to infection. Results: In Group III, the skin contraction rate was the least among the three groups for each three weeks of observation respectively. Also during the three weeks, bacteral colonization was at the highest among the comparison. On the third week, inflammatory cells were still active, but the generations of epidermis and collagen synthesis were detected minimally. Conclusion: The Group III was relatively the most similar model of chronic wounds. and modification of the silicone blocks, could provide us with a very effective chronic skin wound model similar to human.

• 한국결정성장학회지
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• 제26권6호
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• pp.220-224
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• 2016

초음파 스프레이를 이용하여 유리기판 위에 반사방지 박막이 제조되었다. GPTMS와 TEOS는 솔-젤 하이브리드 코팅 용액을 제조하기 위하여 사용되었다. 반사방지막의 코팅 두께를 제어하기 위하여 스프레이 노즐의 이동속도는 15~25 mm/s로 변경되었다. 스프레이 노즐의 이동속도가 증가 됨에 따라 반사방지막의 두께는 138 nm에서 86 nm로 감소되었다. 20 mm/s의 노즐 이동속도에 의해 제조된 반사방지막의 굴절률은 약 1.31, 막의 두께는 104 nm이며, 380 nm에서 780 nm의 가시광 영역에서의 평균 반사율은 0.75 %, 투과율은 94 %로 측정되었다.

• Archives of Plastic Surgery
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• 제33권3호
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• pp.276-282
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• 2006

The anterolateral thigh(ALT) flap has been known as a very versatile and reliable flap. We report our experiences with the anterolateral thigh flap for the postoncologic reconstruction of head and neck region from April 2002 to March 2005. A total of 38 subjects (M: F=30:8, mean age:53.8 years) were taken. We reviewed primary site of tumors, size and thickness of flaps, location and number of perforators, course of perforators, length of pedicle, and postoperative complications. The mean flap size, thickness and pedicle length were $11.8{\times}6.4cm$, 1.1 cm and 12.2 cm, respectively. We classified the pedicles based on the authors' criteria. Type I, pedicle with short intramuscular course, was with 29 cases(72.5%), type II, pedicle with long intramuscular course, with 6 cases(15%), type III, pedicle with septocutaneous course, with 3 cases(7.5%), and type IV, clinically unavailable pedicle, with 2 cases (5%). We experienced 1 case of partial and 1 case of total flap loss. There was 1 case of donor site wound dehiscence, which was treated by debridement and closure. According to the defect, efficient adjustment of the size and thickness of flap was possible, and favorable functional and aesthetic results have been obtained in our study. Our experience confirmed the versatility and usefulness of the anterolateral thigh flap for various reconstructions in head and neck region.

• Journal of Korean Dental Science
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• 제16권2호
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• pp.172-181
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• 2023

Purpose: To investigate the effect of epidermal growth factor (EGF) with collagen matrix (CM) for increasing gingival thickness. Materials and Methods: In five mongrel dogs, bilateral gingival defects were surgically made on the maxillary canines. After two months, either a subepithelial connective tissue graft (group SCTG) or CM with EGF (0.1 ug/ml, group EGF) was grafted, and the flap was coronally positioned to cover the graft materials. The animals were sacrificed after three months. Intraoral scanning was performed for soft tissue analysis. Histologic and histomorphometric analyses were performed. Result: Two animals exhibited wound dehiscence during the healing phase, leaving three for analysis. No statistically significant difference was found in soft tissue changes (P>0.05). The level of gingival margin (GM) increased in both groups (1.02±0.74 mm in group SCTG vs. 1.24±0.83 mm in group EGF). Linear increases at the GM pre-augmentation in the soft tissue profile were 1.08±0.58 mm in group SCTG and 0.96±0.73 mm in group EGF. Histomorphometric parameters (keratinized tissue height, tissue thickness, and rete peg density) were not significantly different between the groups (P>0.05). Conclusion: EGF loaded onto CM led to comparable gingival phenotype enhancement to SCTG.

• 한국전기전자재료학회논문지
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• 제22권7호
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• pp.589-594
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• 2009

We have studied electro-optic characteristics as a function of passivation thickness existing between common electrode and pixel electrodes in the fringe-field switching (FFS) mode using the LC with positive dielectric anisotropy. A steep increase in the transmission is observed with increase in the passivation layer from $0.29{\mu}m$ to $1.09{\mu}m$ and thereafter it almost saturates over the $1.09{\mu}m$ of passivation layer. This saturation is mainly associated with correlation between transmittance at the center region of pixel electrode and at the center region between pixel electrodes. From the results, optimal thickness of passivation layer can be defined.

• 한국정보전자통신기술학회논문지
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• 제9권6호
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• pp.534-538
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• 2016

This paper discusses the characteristics and effects of dielectric inner-supports on discone antenna for broadband RF test chamber, and the verification has been performed by simulation. Several design parameters such as the thickness of the gap support, the position of the side support, and the thickness of the side support has been analyzed. The thickness of the gap support affected the reflection coefficient. An effect of the offset of the side support from the center was slight below 3 GHz and significant above 3 GHz. The thickness of the side support did not affect the reflection coefficient or the gain much. The performance of the fabricated discone antenna was in good agreement with the simulated results. This investigation of a dielectric support effects could be used to design a commercial discone antenna for broadband RF test chamber, focusing on electrical performance and mechanical stability.

• 대한의용생체공학회:의공학회지
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• 제35권6호
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• pp.192-196
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• 2014

Collagen scaffolds were synthesized by cross linking into a solution mixture of 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochlorid(EDC) in ethanol, followed by pressing, cleaning and lyophilization process after the type I atelo-collagen solutions in D.I water(pH3). The experimental conditions are collagen concentration of 1.0 wt%, 3.0 wt%, 5.0 wt% and differential concentration of cross-linker. Then, parametric studies were performed by varying the parameters to investigate the morphology, the porosity, the swelling ratio and the thickness and genotoxicity of the scaffolds. The scaffolds thickness pattern was regular to concentration of the degree of cross-linker and collagen. It was observed that the swelling ratio, the degree of crosslink, and the pore size(thickness of scaffold) can be controlled by adjusting the collagen, crosslinker. Among the parameters investigated, the smallest thickness can be achieved by collagen, crosslinker concentrate condition. The collagen scaffold is induced no genotoxicity. The lowest swelling ratio, as an indication of the highest degree of crosslink, can be obtained by adding crosslink agent.

• 설비공학논문집
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• 제18권3호
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• pp.211-217
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• 2006

The three-dimensional numerical analysis has been carried out to figure out the effect of the thermoelectric element thickness on the thermal performance of the thermo-electric micro-cooler. The small-size and column-type thermoelectric cooler is considered. It is known that tellurium compounds currently have the highest cooling performance around the room temperature. Thus, in the present study, $Bi_{2}Te_{3}$ and $Sb_{2}Te_{3}$ are selected as the n- and p-type thermoelectric materials, respectively. The thermoelectric leg considered is less than $20{\mu}m$ thick. The thickness of the leg may affect the thermal and electrical transport through the interfaces between the leg and metal conductors. The effect of the thermoelectric element thickness on the thermal performance of the cooler has been investigated with parameters such as the temperature difference, the current, and the cooling power.

• Tribology and Lubricants
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• 제35권4호
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• pp.244-266
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• 2019

The purpose of this study is to estimate the wear volumes of engine journal bearings operating at variable angular velocity of a shaft in the beginning of firing start-up cycle. To do this, first we find the potential region of wear scar on engine journal bearings where the applied bearing load and crank shaft velocity are variable. The potential wear regions are discovered by finding minimum oil film thickness at every crank angle existing below most oil film thickness scaring wear (MOFTSW) obtained based on the concept of the centerline average surface roughness. Then we calculate the wear volume from the wear depth and two wear angles decided by the magnitude of each film thickness lower than MOFTSW at every crank angle. The results show that the expected wear region is located at a few bearing angles after and/or behind the upper center of a big-end bearing and the lower center of a main bearing. And the real wear region is similar to the estimated wear region. Further we find that the wear scar on an engine journal bearing may occur at re-starting time after switch-off of a start motor especially under the condition of high oil temperature.

• Tribology and Lubricants
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• 제38권6호
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• pp.281-286
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• 2022

In this study, the effects of Elasto-hydrodynamic lubrication pressure on the critical shoulder height of raceway in an angular contact ball bearing were investigated. Both 3D contact analyses using an influence function and the EHL analysis were conducted for the contact geometry between the ball and raceways. The pressure distributions by 3D contact analysis and EHL analysis for an example bearing were compared. The effect of ellipse truncation on the minimum film thickness also investigated from EHL analysis. The critical shoulder height in the dry contact and the EHL state were compared for various applied loads. It is shown that when the ellipse truncation occurs, the pressure spike for the EHL conjunction is higher than that for the dry contact, and its location moves more inward of the contact center. The steep pressure gradients would increase the flow rate, so in order to maintain flow continuity a significant reduction in film thickness and an abrupt rise in pressure occurs in the edge of shoulder. Significant reduction of the minimum film thickness occurs near the edge of shoulder. The critical shoulder heights in the EHL state are calculated as higher values compared with in the dry contact. This results shows that the determination of critical shoulder height by the EHL analysis is more proper.