• Journal of Yeungnam Medical Science
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• 제9권1호
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• pp.167-174
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• 1992

저자들은 1991년 10월부터 1992년 2월까지 본원 이비인후과를 통해 내원하였던 3명의 환자를 대상으로 경부식도 재건 목적으로 유리전완피판술 2례, 전흉부 축형피판슐 1례를 시행하였으며 다음과 같은 결과를 얻어 이에 문헌고찰과 함께 보고하는 바이다. 1. 유리 전완피판술을 이용하여 피판의 한쪽변을 deepithelization한 후 이중봉합 하였으며, 원위부는 완만한 S자 모양으로 도안하고 하부식도에 틈을 만들어 피판을 삽입함으로서 문제점으로 제기되어온 하부식도문합부 협착, 누공형성등의 합병증을 해결할 수 있었다. 2. 술전 방사선 치료로 수혜부의 혈관을 이용하지 못할때에는 전흉부 축형피판술을 사용하여 만족할 만한 결과를 얻을 수 있었다. 3. 공장 전이술의 합병중인 개복의 번거러움과 수술후 장폐색증, 운동장애, 연하곤란, 음식물의 역류동의 문제점을 해결할 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.328-336
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• 2005

Effects of surface defect distribution on flame instability during flame-surface interaction are experimentally investigated. To examine the chemical quenching phenomenon, we prepared thermally grown silicon oxide plates with well-defined defect density. Ion implantation was used to control the number of defects, i.e. oxygen vacancies. In an attempt to preferentially remove the oxygen atoms from silicon dioxide surface, argon ions with low energy level from 3keV to 5keV were irradiated at the incident angle of $60^{\circ}C$. Compositional and structural modification of $SiO_2$ induced by low-energy $Ar^+$ ion irradiation has been characterized by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). The analysis shows that as the ion energy increases, the number of structural defect also increases and non-stoichiometric condition of $SiO_x(x{\le}2)$ plates is enhanced. From the quenching distance measurements, we found out that when the surface temperature is under $300^{\circ}C$, the quenching distance decreases on account of reduced heat loss; as the surface temperature increases over $300^{\circ}C$, however, quenching distance increases despite reduced heat loss effect. Such aberrant behavior is caused by heterogeneous chemical reaction between active radicals and surface defect sites. The higher defect density, the larger quenching distance. This results means that chemical quenching is governed by radical adsorption and can be parameterized by the oxygen vacancy density on the surface.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.337-343
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• 2020

Oxide dispersed strengthened (ODS) steel is an important candidate for Gen-IV reactors. Oxide embedded in Fe can help to trap irradiation defects and enhances the strength of steel. It was observed in this study that the size of oxide has a profound impact on the depinning mechanism. For smaller sizes, the oxide acts as a void; thus, letting the dislocation bypass without any shear. On the other hand, oxides larger than 2 nm generate new dislocation segments around themselves. The depinning is similar to that of Orowan mechanism and the strengthening effect is likely to be greater for larger oxides. It was found that higher shear deformation rates produce more fine-tuned stress-strain curve. Both molecular dynamics (MD) simulations and BKS (Bacon-Knocks-Scattergood) model display similar characteristics whereby establishing an inverse relation between the depinning stress and the obstacle distance. It was found that (110)_oxide || (111)_Fe (oriented oxide) also had similar characteristics as that of (100)_oxide || (111)_Fe but resulted in an increased depinning stress thereby providing greater resistance to dislocation bypass. Our simulation results concluded that critical depinning stress depends significantly on the size and orientation of the oxide.

• Archives of Plastic Surgery
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• 제36권4호
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• pp.397-405
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• 2009

Purpose: Soft tissue defect of anterior chest wall is caused by trauma, infection, tumors and irradiation. To reconstruct damaged anterior chest wall does require to consider the patient's body condition, the cause, the location, the depth and the size of deletion, the circulation of surrounding tissue and minimization of functional and cosmetic disability. In this report, we suggest the algorithm of configuration for reconstruction methods. Methods: A retrospective study of 20 patients who underwent anterior chest wall reconstruction with pedicled musculocutaneous flap and fasciocutaneous flap was conducted. We collected the information of the patient's body condition, the cause, the size, the depth and the location of deletion, implemented flap and complication. We observed and evaluated flap compatibility, functional and cosmetic results. Patients completed survey about the extent to their satisfaction. Result: Follow up period after surgery was from 6 to 26 months, survival of flap were confirmed in all of patients' case. Two cases of local necrosis, one case of wound disruption were reported, but all these were cured by the debridement and primary closure. One hematoma and one seroma formation were observed in donor site. Longer surgery time, more bleeding amount and more transfusion volume were reported in the group of musculocutenous flap. Conclusion: Long term follow up result showed the successful reconstruction in all patients without recurrence and with minimal donor site morbidity. In addition, the patients' satisfaction for cosmetic and functional results were scaled relatively higher. This confirmed the importance of reconstruction algorithm for the chest wall reconstruction.

• 대한화장품학회지
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• 제29권1호
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• pp.151-167
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• 2003

Melanin biosynthesis is a human defense mechanism to protect skin from UV irradiation and also determines colors of hair and skin. However, as a interest on skin-whitening increases, researches to prevent pigmentation and hypersynthesis of melanin in skin are being actively in progress. Active components used as a whitening agent in cosmeceuticals are kojic acid, arbutin, vitamin C and hydroquinone. However, until now, because comparison researches among them in the aspect of both melanin formation and cellular toxicity have not been performed, we can't exactly estimate merits and defects of them as a whitening agent. To this end, we performed experiments to compare their effects on cell viability and melanin formation. As a first step, in vitro tyrosinase inhibition assay was done. While kojic acid and hydroquinone showed strong inhibition activities(their IC$\_$50/s are all < 100uM), arbutin and vitamin C showed weak activities. IC$\_$50/s of arbutin and vitamin C are 100uM and 400∼500uM, respectively. In B16BL6 melanoma cells, like in vitro tyrosinase inhibition assay, arbutin and kojic acid showed more strong inhibition effect on melanin synthesis than vitamin C. And unlike arbutin, vitamin C and kojic acid induced cell death at high concentration. Although arbutin showed no cytotoxicity, it has side effect to induce morphological change at high concentration.. In this paper, we suggest both kojic acid and arbutin have stronger ability to inhibit melanogenesis than vitamin C. And they also have side effect, that is, kojic acid induces cell death like vitamin C and arbutin changes cell morphology respectively.

• 한국재료학회지
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• 제19권4호
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• pp.192-197
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• 2009

Carbon nanotubes (CNT) were used as a catalyst support where catalytically active Pd and Pt metal particles decorated the outside of the external CNT walls. In this study, Pd and Pt nanoparticles supported on $HNO_3$-treated CNT were prepared by microwave-assisted heating of the polyol process using $PdCl_2$ and $H_2PtCl_6{\codt}6H_2O$ precursors, respectively, and were then characterized by SEM, TEM, and Raman. Raman spectroscopy showed that the acid treated CNT had a higher intensity ratio of $I_D/I_G$ compared to that of non-treated CNT, indicating the formation of defects or functional groups on CNT after chemical oxidation. Microwave irradiation for total two minutes resulted in the formation of Pd and Pt nanoparticles on the acid treated CNT. The sizes of Pd and Pt nanoparticles were found to be less than 10 nm and 3 nm, respectively. Furthermore, the $SnO_2$ films doped with CNT decorated by Pd and Pt nanoparticles were prepared, and then the $NO_2$ gas response of these sensor films was evaluated under $1{\sim}5\;ppm$ $NO_2$ concentration at $200^{\circ}C$. It was found that the sensing property of the $SnO_2$ film sensor on $NO_2$ gas was greatly improved by the addition of CNT-supported Pd and Pt nanoparticles.

• 한국광학회지
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• 제16권2호
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• pp.113-120
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• 2005

LCD-BLU(liquid crystal device-back light unit)에 사용되는 도광판의 미세 산란패턴을 만드는 새로운 방법으로서, 실리콘 웨이퍼의 비등방 식각에 의해 자연적으로 형성되는 3차원 결정면 구조를 이용하는 방법을 제안하였다. 실리콘 3차원 결정면을 갖는 도광판과 프리즘 시트의 원판을 설계 및 제작하였고, casting 공정을 통해 PDMS 재질로 복제된 도광판을 제작하여 특성을 분석하였다. 측정 결과, 기존 인쇄형 도광판에 비해 실리콘피라미드 패턴의 도광판이 $10\%$ 증가된 정면 휘도 효율을 가질 수 있음을 실험적으로 검증하였다.

• 한국광물학회지
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• 제22권4호
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• pp.407-415
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• 2009

전자빔 조사를 조사량에 따라 단계별로 수행하면서 전자빔을 조사하는 동안 다이아몬드 내에서 일어나는 질소관련 결함의 변화와 색상의 변화를 분광학적 방법으로 측정 분석하였다. 일반적으로 질소의 양이 적을수록 공공이 쉽게 생성되며 A집합체보다 B집합체가 많은 시료에서 공공이 빠르게 생성된다는 결과를 보였다. 그 이유로 공공의 생성 정도가 전자빔에 의해 파괴될 수 있는 크기를 가진 결함의 양 즉, platelets에 비례한다는 결론을 추론할 수 있었다. 그리고 조사량이 증가할수록 옅은 녹색을 지닌 청색에서 짙은 청색으로 변화한다. 이러한 청색의 발현은 GR1센터의 점진적인 증가로 GR1센터 흡수포논에 의한 흡수띠의 영역은 더욱 확장되어 가시광선이 투과하는 최고 파장대가 530 nm에서 500 nm로 이동하면서 나타나는 현상이다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권12호
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• pp.545-552
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• 2003

When a Si PIN diode is exposed to fast neutrons, it results in displacement damage to the Si lattice structure of the diode. Defects induced from structural dislocation become effective recombination centers for carriers which pass through the base of a PIN diode. Hence, increasing the resistivity of the diode decreases the current for the applied forward voltage. This paper involves the development of a neutron sensor based on the phenomena of the displacement effect damaged by neutron exposure. The neutron effect on the semiconductor was analyzed. Several PIN diode arrays with various thickness and cross-section area of the intrinsic layer(I layer) were fabricated. Under irradiation tests with a neutron beam, the manufactured diodes have a good linearity to neutron dose and show that the increase of thickness of I layer and the decrease of cross-section of PIN diodes improve the sensitivity. Newly developed PIN diodes with thicker I layer and various cross section, were retested and then showed the best neutron sensitivity at the condition that the I layer thickness was similar to a side length. On the basis of two test results, final discrete PIN diodes with a rectangular shape were manufactured and the characteristics as neutron detectors were analyzed through the neutron beam test using on-line electronic dosimetry system. Developed PIN diode shows a good linearity as dosimetry in the range of 0 to 1,000cGy(Tissue) and its neutron sensitivity is 13mV/cGy at constant current of 5mA, that is three times higher than that of commercially available neutron detectors. And the device shows little dependency on the orientation of the neutron beam and a considerable stability in annealing test for a long period.

• 대한두개안면성형외과학회지
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• 제22권4호
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• pp.204-208
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• 2021

Sebaceous carcinoma is a malignant neoplasm that usually arises in the sebaceous glands of the eyelids. Its pathogenesis is unknown; however, irradiation history, immunosuppression, and use of diuretics are known risk factors. The mainstay of treatment for sebaceous carcinoma of the eyelid is wide surgical resection with a safety margin of 5 to 6 mm, which often results in full-thickness defects. The reconstruction of a full-thickness defect of the eyelid should be approached using a three-lamella method: a mucosal component replacing the conjunctiva, a cartilage component for the tarsal plate, and a flap or skin graft for the skin of the eyelid. In this case, a full-thickness defect of the upper eyelid was reconstructed after tumor removal using a combination of a nasal septum chondromucosal composite graft and a forehead transposition flap, also known as a "Fricke flap." The flap was designed to include a line of the eyebrow on the lower margin of the flap to replace the eyelash removed during tumor excision. The wound healed completely, without any early or late complications, and the outcome was satisfactory.