• Journal of Yeungnam Medical Science
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• 제23권1호
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• pp.19-25
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• 2006

심실중격결손이나 심방중격결손과 같이 대동맥 차단시간이 길지 않은 질환에 있어서는 HTK용액의 심근보호효과가 냉혈심정지액과 비슷한 효과를 가짐을 알 수 있었다. 따라서 한번 투여로 2~3시간의 수술이 가능한 장점을 가진 HTK용액을 소아에서도 유용하게 사용할 수 있을 것으로 생각되며 향후 복잡심기형과 같은 긴 대동맥차단이 요구되는 소아환자의 안정성에 대해서는 더 많은 연구가 필요할 것으로 생각된다.

• Current Optics and Photonics
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• 제6권6호
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• pp.521-549
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• 2022

Fiber lasers have made remarkable progress over the past three decades, and they now serve far-reaching applications and have even become indispensable in many technology sectors. As there is an insatiable appetite for improved performance, whether relating to enhanced spatio-temporal stability, spectral and noise characteristics, or ever-higher power and brightness, thermal management in these systems becomes increasingly critical. Active convective cooling, such as through flowing water, while highly effective, has its own set of drawbacks and limitations. To overcome them, other synergistic approaches are being adopted that mitigate the sources of heating at their roots, including the quantum defect, concentration quenching, and impurity absorption. Here, these optical methods for thermal management are briefly reviewed and discussed. Their main philosophy is to carefully select both the lasing and pumping wavelengths to moderate, and sometimes reverse, the amount of heat that is generated inside the laser gain medium. First, the sources of heating in fiber lasers are discussed and placed in the context of modern fiber fabrication methods. Next, common methods to measure the temperature of active fibers during laser operation are outlined. Approaches to reduce the quantum defect, including tandem-pumped and short-wavelength lasers, are then reviewed. Finally, newer approaches that annihilate phonons and actually cool the fiber laser below ambient, including radiation-balanced and excitation-balanced fiber lasers, are examined. These solutions, and others yet undetermined, especially the latter, may prove to be a driving force behind a next generation of ultra-high-power and/or ultra-stable laser systems.

• 한국결정성장학회지
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• 제19권2호
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• pp.75-78
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• 2009

PBN 도가니를 이용하여 Si이 도핑된 GaAs 단결정을 수직경사 응고법으로 성장시켰다. PBN 도가니에 산화막인 $B_{2}O_{3}$의 양을 $0{\sim}0.2wt%$ 범위에서 변화시키면서, 성장 후 캐리어 농도를 측정하였다. $B_{2}O_{3}$ 첨가량이 증가함에 따라, 초기 0.1 정도의 Si 도판트의 편석계수는 0.01 부근까지 급격히 감소하고, 동시에 캐리어 농도도 감소하는 것을 알 수 있었다. 이는 성장도중 도판트인 Si이 $B_{2}O_{3}$과 반응하며 도너인 Si 양을 감소시키며, 동시에 억셉터인 B 양을 증가시키기 때문으로 보인다. 한편 PBN 도가니 내면에 얇은 유리질의 $B_{2}O_{3}$층 형성이 용이한 고온 산화막 처리가 결함감소에 효과적임을 확인하였다.

• Journal of Korean Neurosurgical Society
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• 제58권2호
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• pp.101-106
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• 2015

Objective : The aim of this study was to explore the immunity in rats transplanted with adipose-derived mesenchymal stem cells (ADSCs) and acellular nerve (ACN) for repairing sciatic nerve defects. Methods : ADSCs were isolated from the adipose tissues of Wistar rats. Sprague-Dawley rats were used to establish a sciatic nerve defect model and then divided into four groups, according to the following methods : Group A, allogenic nerve graft; Group B, allograft with ACN; Group C, allograft ADSCs+ACN, and Group D, nerve autograft. Results : At the day before transplantation and 3, 7, 14, and 28 days after transplantation, orbital venous blood of the Sprague-Dawley rats in each group was collected to detect the proportion of $CD3^+$, $CD4^+$, and $CD8^+$ subsets using flow cytometry and to determine the serum concentration of interleukin-2 (IL-2), tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$) and $interferon-{\gamma}$ ($IFN-{\gamma}$) using enzyme-linked immunosorbent assay (ELISA). At each postoperative time point, the proportion of $CD3^+$, $CD4^+$, and $CD8^+$ subsets and the serum concentration of IL-2, $TNF-{\alpha}$, and $IFN-{\gamma}$ in group C were all near to those in group B and group D, in which no statistically significant difference was observed. As compared with group A, the proportion of $CD3^+$, $CD4^+$, and $CD8^+$ subsets and the serum concentration of IL-2, $TNF-{\alpha}$, and $IFN-{\gamma}$ were significantly reduced in group C (p<0.05). Conclusion : The artificial nerve established with ADSCs and ACN has no obvious allograft rejection for repairing rat nerve defects.

• 한국재료학회지
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• 제21권4호
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• pp.192-195
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• 2011

The electro-deposition of compound semiconductors has been attracting more attention because of its ability to rapidly deposit nanostructured materials and thin films with controlled morphology, dimensions, and crystallinity in a costeffective manner (1). In particular, low band-gap $A_2B_3$-type chalcogenides, such as $Sb_2Te_3$ and $Bi_2Te_3$, have been extensively studied because of their potential applications in thermoelectric power generator and cooler and phase change memory. Thermoelectric $Sb_xTe_y$ films were potentiostatically electrodeposited in aqueous nitric acid electrolyte solutions containing different ratios of $TeO_2$ to $Sb_2O_3$. The stoichiometric $Sb_xTe_y$ films were obtained at an applied voltage of -0.15V vs. SCE using a solution consisting of 2.4 mM $TeO_2$, 0.8 mM $Sb_2O_3$, 33 mM tartaric acid, and 1M $HNO_3$. The stoichiometric $Sb_xTe_y$ films had the rhombohedral structure with a preferred orientation along the [015] direction. The films featured hole concentration and mobility of $5.8{\times}10^{18}/cm^3$ and $54.8\;cm^2/V{\cdot}s$, respectively. More negative applied potential yielded more Sb content in the deposited $Sb_xTe_y$ films. In addition, the hole concentration and mobility decreased with more negative deposition potential and finally showed insulating property, possibly due to more defect formation. The Seebeck coefficient of as-deposited $Sb_2Te_3$ thin film deposited at -0.15V vs. SCE at room temperature was approximately 118 ${\mu}V/K$ at room temperature, which is similar to bulk counterparts.

• 한국분말재료학회지
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• 제23권2호
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• pp.91-94
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• 2016

High-quality colloidal CdSe/ZnS (core/shell) is synthesized using a continuous microreactor. The particle size of the synthesized quantum dots (QDs) is a function of the precursor flow rate; as the precursor flow rate increases, the size of the QDs decreases and the band gap energy increases. The photoluminescence properties are found to depend strongly on the flow rate of the CdSe precursor owing to the change in the core size. In addition, a gradual shift in the maximum luminescent wave (${\lambda}_{max}$) to shorter wavelengths (blue shift) is found owing to the decrease in the QD size in accordance with the quantum confinement effect. The ZnS shell decreases the surface defect concentration of CdSe. It also lowers the thermal energy dissipation by increasing the concentration of recombination. Thus, a relatively high emission and quantum yield occur because of an increase in the optical energy emitted at equal concentration. In addition, the maximum quantum yield is derived for process conditions of 0.35 ml/min and is related to the optimum thickness of the shell material.

• 전기전자학회논문지
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• 제2권1호
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• pp.101-107
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• 1998

인(Phosphorus)을 1MeV로 이온 주입한 후 RTA를 실시하여 미세결함의 특성을 조사하고, 면저항, SRP, SIMS, XTEM 분석과 CMOS 구조에서 래치업 특성을 모의 실험하였다. 도즈량이 증가할수록 면저항은 낮아지고, Rp값은 도즈량이 $1{\times}10^{13}/cm^2,\;5{\times}10^{13}/cm^2,\;1{\times}10^{14}/cm^2$일때 각각 $1.15{\mu}m,\;1.15{\mu},\;1.10{\mu}m$로 나타났다. SIMS 측정결과는 열처리 시간이 길수록 농도의 최대치가 표면으로부터 깊어지고, 농도 또한 낮아짐을 확인하였다. XTEM 분석 결과는 열처리 전에는 결함측정이 불가능했으나, 측정되지 많은 미세결함이 열처리 후 이차결함으로 성장한 것으로 조사되었다. 모의 실험은 buried layer와 connecting layer 구조를 사용하였으며, buried layer보다 connecting layer가 래치업 특성이 우수함을 확인하였다. Connecting layer의 도즈량이 $1{\times}10^{14}/cm^2$이고 이온주입 에너지가 500KeV일 때 trigger current는 $0.6mA/{\mu}m$이상이었고, trigger voltage는 약 6V로 나타났다. Connecting layer의 이온주입 에너지가 낮을수록 래치업 저감효과가 더욱 우수함을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제34권4호
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• pp.251-255
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• 2021

a-Si is commonly considered as a primary candidate for the formation of passivation layer in heterojunction (HIT) solar cells. However, there are some problems when using this material such as significant losses due to recombination and parasitic absorption. To reduce these problems, a wide bandgap material is needed. A wide bandgap has a positive influence on effective transmittance, reduction of the parasitic absorption, and prevention of unnecessary epitaxial growth. In this paper, the adoption of a-SiO_x:H as the intrinsic layer was discussed. To increase lifetime and conductivity, oxygen concentration control is crucial because it is correlated with the thickness, bonding defect, interface density (D_it), and band offset. A thick oxygen-rich layer causes the lifetime and the implied open-circuit voltage to drop. Furthermore the thicker the layer gets, the more free hydrogen atoms are etched in thin films, which worsens the passivation quality and the efficiency of solar cells. Previous studies revealed that the lifetime and the implied voltage decreased when the a-SiOx thickness went beyond around 9 nm. In addition to this, oxygen acted as a defect in the intrinsic layer. The D_it increased up to an oxygen rate on the order of 8%. Beyond 8%, the D_it was constant. By controlling the oxygen concentration properly and achieving a thin layer, high-efficiency HIT solar cells can be fabricated.

• Asian-Australasian Journal of Animal Sciences
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• 제27권10호
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• pp.1417-1425
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• 2014

The selection of morphologically normal spermatozoa is critical to obtain high breeding performances in boar breeding farms and artificial insemination (AI) centers. Parameters for the selection of semen mainly include total sperm motility, concentration, and morphology. However, these primary parameters are often not reliable for discriminating between normal and abnormal, non-fertilizable spermatozoa. The present study was designed to compare the motion characteristics, fertilization ability using in vitro fertilization (IVF), and acrosome formation of the semen from boars having low (boar number 2012) and normal (boar number 2004 and 2023) breeding performances. The ultimate goal was to identify additional simple and easy criteria for the selection of normal sperm. There was no significant difference between boar 2004 and boar 2023 sperm total motility in computer assisted sperm analysis. However, boar number 2012 semen presented a significantly reduced population of rapid moving spermatozoa and an increased population of slow moving spermatozoa compared to boar numbers 2004 and 2023. Analysis of detailed motion characteristics revealed that sperm from boar number 2012 had significantly reduced motility in progressiveness, average path velocity, straight-line velocity (VSL), curvilinear velocity (VCL), straightness, and linearity. The assessment of the fertilizing ability by IVF also showed that sperm from boar number 2012 showed a fertility rate of 3.4%, whereas sperm from boar number 2023 had a fertility rate of 75.45%. Interestingly, most of the sperm nuclei were found on the peripheral area of the oocytes, suggesting that the sperm from boar number 2012 lacked penetration ability into the oocyte zonapellucida. The acrosome formation analysis using Pisum sativum agglutinin staining demonstrated that the sperm from boar number 2012 had a defect in acrosome formation. Consequently, primary parameters for selecting semen before AI such as motility are not sufficient to select normal and fertilizable spermatozoa. In conclusion, the present study suggests that the acrosome staining and detailed motion characteristics such as progressiveness, VCL, and VSL should be included in determining semen quality together with primary parameters for successful AI and high breeding performance in the swine industry.

• 한국건설관리학회논문집
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• 제14권5호
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• pp.55-64
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• 2013

의료시설은 일반건축물 보다 공사의 복잡성이 높고, 정부규제가 엄격하여 공사 단계에서의 설계변경과 하자보수들이 많이 발생한다. 본 연구에서는 의료시설의 중점 관리공사와 요인들을 도출하고 분석하여, 설계단계와 공사단계에서 관리가 잘 되지 않는 공사들을 분석하였다. 그리고 2013년 현재 진행되고 있는 의료시설 공사 관리자들의 인식을 조사하여, 개선 가능성이 큰 공사를 도출하였다. 먼저, 중점 관리요인들을 건축과 설비, 그리고 전기의 세 분야로 분류하여 도출하였다. 다음으로, 1) 공사 진행단계에서 설계변경이 많이 발생하고, 2) 하자보수들이 많이 발생하고 소요비용이 큰 중점 관리공사와 요인들을 분석하였다. 마지막으로, 진행 중인 의료시설 공사 관리자들이 중요하게 생각하지 않는 공사를 조사하였다. 설계변경과 하자보수가 많지만, 중요하게 생각하고 있지 않다면 개선 가능성이 클 것이기 때문이다. 설계단계에서는 마감공사, 벽체공사, 창호공사, 사무 자동화 및 통신기능 공사, 조명공사, 그리고 공사 관리단계에서는 폐기물 공사, 사무자동화 통신기능, 창호공사, 오염관리, 배관공사로 분석되었다. 본 연구의 결과인 설계변경과 하자보수가 많은 공사, 그리고 개선 가능성이 큰 공사의 관리를 실시 설계단계와 공사 관리단계에서부터 집중 관리하여야 할 것이다.