• Korean Chemical Engineering Research
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• 제50권1호
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• pp.177-181
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• 2012

본 연구에서는 $TiO_2$ 필름에 그라핀나노시트(graphenenanosheet, GNS)의 양을 다르게 함으로써 형성한 전극을 이용하여 염료감응형 태양전지를 제작하였고 그 특성을 연구하였다. $TiO_2$-GNS 혼합물 전극은 단순한 혼합방식에 의하여 제작되었으며, N3를 염료로 사용하여 태양전지의 효율을 평가하였다. $TiO_2$-GNS 혼합물 전극을 사용한 염료감응형 태양전지의 전환효율은 GNS의 양에 의해 영향을 받았으며, $TiO_2$에 GNS를 0.01 wt% 혼합한 전극을 사용하여 제작한 염료감응형 태양전지가 가장 높은 효율인 5.73%를 나타내었다. 이는 GNS를 혼합하지 않은 전극을 사용한 태양전지보다 26% 높은 효율이었다. 이와 같은 효율 증가의 원인으로는 GNS 첨가에 의한 N3의 흡착량 증가, 전자 재결합(electron recombination)과 back transport reaction의 감소, 전자 수송의 증가로부터 기인한 것으로 생각된다. 본 연구에서 $TiO_2$(anatase)와 GNS의 존재는 Field-Emission Scanning Electron Microscopy를 통하여 확인하였으며, 흡착된 염료의 양은 자외선분광기(UV-vis Spectroscopy), 전자 재결합의 감소 및 전자 수송에 대한 분석은 전기화학적 임피던스분광법(Electrochemical Impedance Spectroscopy)을 이용하였다.

• 한국수정란이식학회:학술대회논문집
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• 한국수정란이식학회 2002년도 국제심포지엄
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• pp.92-92
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• 2002

Considerable attention has been focused on the cryopreservation of semen and estrus induction in dog, as consequence of poor productivity caused by long anestrus period, in order to enhance the productivity of youngs and to preserve the breeds. The objectives of this study were to evaluate semen quality after cryopreservation and to evaluate the Pregnancy rate after insemination (AI). Fifty infertilie dogs (age 2∼3 years) were selected for the study and divided into three different estrus induction treatment groups. Group 1: dogs (n=15) were given clomifene (0.1 mg/kg) orally for five days at 12 hr intervals. Group 2: dogs (n=15) were given bromocriptine (50 $\mu\textrm{g}$/kg) orally for five days at 12 hr intervals, followed by single injection intravenously of 500 IU GnRH (Group 3, n=20) when pro-estrus occurred. The rates of pregnancy in estrus inducted dogs mated naturally compared to those inseminated artificially with ejaculated fresh semen and frozen-thawed semen. Estrus detection was performed using the method of vaginal smear and confirmed by the plasma progesterone assay. The ejaculated semen to freeze was exposed to a mixture of Tris extender with cryoprotectant (Trisma, 81 mM: TES, 209 mM: citric acid, 6 mM; glucose, 5 mM; glycerol, 8%) and cryopreserved gradually by slow-cooling at 17 cm above the surface of liquid nitrogen (LN$_2$) for 23 min. The motility of frozen-thawed spermatozoa was assessed by phase-contrast microscopy. To assess their viability and acrosome content, spermatozoa were stained with a vital stain and Fluorescence conjugated lectin Pisum Savitum Agglutinin (FITC/PAS), respectively. Pregnancy was confirmed by ultrasonograpy on day 25, 35 and 55 post insemination. The use of fresh semen, the pregnancy rates were observed 66.6, 66.6, 75.0 and 83.3% in natural estrus, clomifene induced, bromocriptine induced and a combination of GnRH and bromocriptine, respectively. The use of frozen-thawed semen, the pregnancy rates were observed 66.6, 33.3, 50.0 and 60.0% in natural estrus, clomifene induced, bromocriptine induced and a combination of GnRH and bromocriptine, respectively. No difference was observed in the number of offspring produced among natural estrus and treated groups inseminated with fresh or frozen-thawed semen. In conclusion, the pregnancy rate of dogs treated with a combination of GnRH and bromocriptine was more effective than use of clomifene or bromocriptine only. In addition, frozen-thawed semen can be used successfully far artificial insemination in dog.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권3호
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• pp.275-279
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• 2005

Insect cell transformants, stably expressing human $GFP_{uv}-{\beta}1$, 3-N-acetylglucosaminyltransferase 2 $({\beta}3GnT2)$ as the green fluorescent protein $(GFP_{uv})-fused$ protein, were efficiently isolated on Western blot by the quantification of the densitometric intensity of the fusion protein. From almost 150 transformants containing the fusion gene linked to three different types of signal sequence, two transformants, Tn-pXme4a and -pX28a, were successfully selected, showing 8.3 and 8.6 mU/mL ${\beta}3GnT$ activity, respectively. This method requires a screening time almost one-half that required in the isolation of stably transformed cells with high expression levels, and at the same time allows the handling a large number of transformants.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.196-200
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• 2011

In this work, poly(methyl methacrylate) (PMMA) was grafted onto amine treated graphite nanosheets ($NH_2$-GNs) and the surface characteristics and physical properties of the $NH_2$-GNs-g-PMMA films were investigated. The graft reaction of $NH_2$-GNs and PMMA was confirmed from the shift of the $N_{1S}$ peak, including amine oxygen and amide oxygen, by X-ray photoelectron spectroscopy (XPS). The surface characteristics of the $NH_2$-GNs-g-PMMA films were measured as a function of the $NH_2$-GN content using the contact angle method. It was revealed that the specific component of the surface free energy (${\gamma}s$) of the films was slightly increased as the $NH_2$-GN content increased. Also, the thermal and mechanical properties of the $NH_2$-GNs-g-PMMA films were enhanced with the addition of $NH_2$-GNs. This can be attributed to the chemical bonding caused by the graft reaction between the $NH_2$-GNs and the PMMA matrix.

• 한국태양에너지학회 논문집
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• 제35권1호
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• pp.89-96
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• 2015

n-octadecnae based shape stabilized phase change material (SSPCM) was prepared by using vacuum impregnation method. And an exfoliated graphite nanoplate (xGnP) which has high thermal conductivity properties is used as a PCM container. And then we made heat storage concretes which contains SSPCM for reducing heating and cooling load in buildings. In the prepararion process, the SSPCM was mixed to a concrete as 10, 20 and 30wt% of cement weight. The thermal properties and chemical properties of heat storage concrete were analyzed from Scanning electron microscope (SEM), Fourier transformation infrared spectrophotometer (FT-IR), Deferential scanning calorimeter (DSC), Thermogravimetric analysis (TGA) and TCi thermal conductivity analyzer. And we conducted surface temperature analysis of SSPCM and xGnP by using heat plate and insulation mold.

• 한국발생생물학회지:발생과생식
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• 제1권1호
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• pp.79-89
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• 1997

Recent studies have demonstrated that apoptotic cell death plays an important role in the mechanism underlying follicular atresia and luteolysis. However, the mechanisms responsible for initiating these processes have not been elucidated. In in vitro fertilization (IVF) programs, it is highly possible that continuous and repeated administration of FSH/hMG and GnRH agonists for the usage of ovarian hyperstimulation may induce apoptotic death of granulosa cells leading to atresia in the human ovarian follicles. The present study was performed to investigate whether FSH/hMG and GnRh agonists used for a longer period in controlled ovarian hyperstimulation has any effect on the apoptosis of granulosa-luteal (GL) cells obtained from hyperstimulated ovaries. To examine apoptotic cell death in the GL cells, cells were stained with acridie orange followed by observed in some of GL cells. Similar but distinct staining of apoptotic GL cells was observed when the cells were examined by using in situ TUNEL method. The healthy-looking cells with normal nuclear morphology were not stained, whereas cells with pyknotic nuclei or with apoptotic nuclei were intensively stained. After examining the ultrastructural features of GL cells by TEM, it was confirmed that the majority of cells seemed to have normal nuclei while GL cells undergoing apoptotic cel death were rarely found. The DNA extracted from GL cells showed a typical pattern of fragmentation following DNA electrophoretic analysis. We have confirmed that the apoptosis occurs in granulosa-luteal cells obtained from hyperstimulated ovaries. Technically, in situ apoptosis detection method is simple and reproducible and is well suited to identify the quality of oocytes retrieved from hyperstimulated ovaries.

• 한국재료학회지
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• 제22권10호
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• pp.504-507
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• 2012

Synthesis of RGO (reduced graphene oxide)-CdS composite material was performed through CBD (chemical bath deposition) method in which graphene oxide served as the support and Cadmium Sulfate Hydrate as the starting material. Graphene-based semiconductor photocatalysts have attracted extensive attention due to their usefulness for environmental and energy applications. The band gap (2.4 eV) of CdS corresponds well with the spectrum of sunlight because the crystalline phase, size, morphology, specic surface area and defects, etc., of CdS can affect its photocatalytic activity. The specific surface structure (morphology) of the photocatalyst can be effective for the suppression of recombination between photogenerated electrons and holes. Graphene (GN) has unique properties such as a high value of Young's modulus, large theoretical specific surface area, excellent thermal conductivity, high mobility of charge carriers, and good optical transmittance. These excellent properties make GN an ideal building block in nanocomposites. It can act as an excellent electron-acceptor/transport material. Therefore, the morphology, structural characterization and crystal structure were observed using various analytical tools, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. From this analysis, it is shown that CdS particles were well dispersed uniformly in the RGO sheet. Furthermore, the photocatalytic property of the resulting RGO-CdS composite is also discussed in relation to environmental applications such as the photocatalytic degradation of pollutants. It was found that the prepared RGO-CdS nanocomposites exhibited enhanced photocatalytic activity as compared with that of CdS nanoparticles. Therefore, better efficiency of photodegradation was found for water purification applications using RGO-CdS composite.

• Structural Engineering and Mechanics
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• 제49권1호
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• pp.41-64
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• 2014

The main objective of this article is the exploitation of a stochastic hybrid mesh-free method based on stochastic generalized finite difference (SGFD), Newmark finite difference (NFD) methods and Monte Carlo simulation for thermoelastic wave propagation and coupled thermoelasticity analysis based on GN theory (without energy dissipation). A thick hollow cylinder with Gaussian uncertainty in mechanical properties is considered as an analyzed domain for the problem. The effects of uncertainty in mechanical properties with various coefficients of variations on thermo-elastic wave propagation are studied in details. Also, the time histories and distribution on thickness of cylinder of maximum, mean and variance values of temperature and radial displacement are studied for various coefficients of variations (COVs).

• Journal of Animal Science and Technology
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• 제49권6호
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• pp.753-760
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• 2007

본 시험은 돼지에서 면역생물학 제제 투여에 따른 거세 효과를 구명하기 위해서 수행되었다. 공시동물은 2원교잡종(Landrace×Yorkshire) 21일령 자돈 45두를 공시하였고, 시험사육은 출하체중 110kg 도달 때까지 실시하였다. 시험구 배치는 비거세구(NC), 거세구(SC), 면역생물학 제제 투여구(GA)로 나누어 돈방당 5두씩 완전임의 배치하여 3회 반복하였다. 거세는 생후 3-4일령의 자돈에서 외과적 방법으로 실시하였다. 면역생물학 제제 투여는 GnRH antagonist (Improvac, Pfizer Australia)를 시험개시 후 16주와 20주에 각각 두당 2ml씩 2회에 걸쳐 피하주사하였다. 면역생물학 제제 투여에 따른 생산성은 다른 처리구에 비해 유의적인 차이는 나타나지 않았다. 도체특성에서, 정육율과 체지방 함량은 면역생물학 제제 투여에 의해 외과적 거세와 유사한 효과를 나타내었다. 육질 특성에서, 육색, pH, 전단력 및 가열 감량은 유의적인 차이를 나타내지 않았다. 혈중 testosterone 농도는 면역생물학 제제 2차 투여 2주 후에 일반 거세와 유사한 경향을 보였다. 생식기에서 정소 직경, 무게 및 요도구선 무게는 면역생물학 제제 투여에 의해서 비거세 돼지보다 유의적으로 작았다(P=0.002).따라서 본 시험에 이용한 면역생물학 제제를 투여하였을 때 도체 및 육질에 있어서 일반 거세와 비슷한 효과를 나타내었으므로 외과적 수술에 의한 거세를 대처할 수 있을 것으로 사료된다.

• 한국수정란이식학회지
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• 제17권2호
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• pp.153-162
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• 2002

본 연구에서는 한우의 신속한 증식을 위한 번식기술 개발을 위해 발정이 재귀되지않은 무발정 한우의 번식장애 치료효과와 공태기를 감축하기 위한 난소실질내 PGF／sub 2$\alpha$처치효과를 알아보았다. 1. 번식장애의 감별진단 결과는 검사두수 43두중 둔성발정 또는 발정발견의 잘못이 18두 (41.9%)로 가장 많았고, 난소기능정지 14두 (32.6%), 난포낭종 4두(9.3%), 영구황체 3두 (7.0%), 자궁내막염 2두 (4.7%), 자궁축농증과 황체낭종은 각각 1두(2.3%)로 나타났다. 2. 둔성발정 또는 발정발견의 잘못 18두를 PGF／sub 2$\alpha$／ 25 mg으로치료하여 18두가 발정이 발현되었고 이중 16두 임신되었다. 3. 난소기능정지의 경우는 GnRH 200$\mu\textrm{g}$으로 치료하여 10두중 8두가 발정이 발현되어 이중 7두가 임신이 되었으며, 난포낭종도 역시 CnRH 200$\mu\textrm{g}$으로 치료하여 4두중 3두가 발정이 발현되어서 인공수정후 임신이 되었다. 4. 영구황체 3두와 황체낭종 1두는 각각 PGF／sub 2$\alpha$／ 25 mg으로 치료하여 3두 모두 발정이 발현되어 수정후 임신이 되었다. 5. 자궁내막염 2두는 PGF／sub 2$\alpha$／25mg과 항생제 요법을 병행한 결과 2두 모두 발정이 발현되어서 인공수정후 임신이 되었다. 6.공태기를 줄이기 위한 방법으로 분만 후 20일이 경과한 소에 대해 14일 간격으로 PGF／sub 2$\alpha$/의 난소실질내 투여시 공여동물 23두중 17두에서 임신이 확인되어 74%의 수태율을 보였다. 또한 11일 간격으로 PGF／sub 2$\alpha$／ 를 투여한 군에서는 17두중 16두가 임신되어 94%의 높은 수태율을 보여 공태기를 더 단축할 수 있는 우수한 처리법임을 알 수 있었다.