• Reproductive and Developmental Biology
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• 제30권3호
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• pp.181-187
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• 2006

최근 돼지의 장기를 사람에게 이식하는 이종간 장기 이식에 관한 연구가 급속히 발전되고 있다. 그러나 돼지의 장기를 이식할 경우 가장 큰 문제점 중의 하나는 돼지 genome 내에 존재하는 내인성 레트로바이러스(porcine endogenous retrovirus; PERV)가 인간에게 그대로 전이될 수 있다는 것이다. 이에 대한 대안으로 최근 활발히 연구되고 있는 RNA 간섭을 통한 PERV RNA의 발현을 최대한 억제하는 방법이 제안되고 있는데, RNA 간섭(RNA interference)은 double-standard RNA(dsRNA)가 상보적인 표적 mRNA를 분해하여 결과적으로 표적 단백질의 발현을 특이적으로 억제하는 현상을 의미한다. 본 연구에서는 PERV에 대한 RNA 간섭 현상을 일으키는 shRNA 유전자를 레트로바이러스 벡터를 이용하여 돼지세포에 RNA)가 상보적인 표적 mRNA를 분해하여 결과적으로 표적 단백질의 발현을 특이적으로 억제하는 현상을 의미하다. 도입한 후 PERV의 발현율 감소 여부를 조사하였다. 그 결과, gag-pol 유전자와 env 유전자 발현은 각각 대조군 세포의 4%와 10% 정도로 억제되었다. 한편, virus 입자의 생산에서 gag-pol 유전자는 대조군 세포에 비해 300배 이상 억제되었으며, env 유전자에서는 20만 배 이상 억제되었다. 이상의 결과를 미루어 볼 때 형질 전환 돼지를 이용한 이종 장기 이식에 있어서 RNA 간섭 현상을 이용한 PERV의 발현을 억제하는 시도는 생물학적안전성을 크게 증가시킬 수 있을 것으로 사료된다.

• 한국자기공명학회논문지
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• 제12권1호
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• pp.1-13
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• 2008

Acetyl-CoA carboxylase (ACC) catalyzes the first step in fatty acid biosynthesis: the synthesis of malonyl-CoA from acetyl-CoA. As essential regulators of fatty acid biosynthesis and metabolism, ACCs are regarded as therapeutic targets for the treatment of metabolic diseases such as obesity, In ACC, the biotinoyl domain performs a critical function by transferring an activated carboxyl group from the biotin carboxylase domain to the carboxyl transferase domain, followed by carboxyl transfer to malonyl-CoA. Despite the intensive research on this enzyme, only the bacterial and yeast ACC structures are currently available, To explore the mechanism of ACC holoenzyme function, we determined the structure of the biotinoyl domain of human ACC2 and analyze its characteristics using NMR spectroscopy. The 3D structure of the hACC2 biotinoyl domain has a similar folding topology to the previously determined domains from E. coli and P. Shermanii, however, the 'thumb' structure is absent in the hACC2 biotinoyl domain. Observations of the NMR signals upon the biotinylation indicate that the biotin group of hACC2 does not affect the structure of the biotinoyl domain, while the biotin group for E. coli ACC interacts directly with the thumb residues that are not present in the hACC2 structure. These results imply that, in the E. coli ACC reaction, the biotin moiety carrying the carboxyl group from BC to CT can pause at the thumb of the BCCP domain. The human biotinoyl domain, however, lacks the thumb structure and does not have additional non-covalent interactions with the biotin moiety; thus, the flexible motion of the biotinylated lysine residue must underlie the "swinging arm" motion. This study provides insight into the mechanism of ACC holoenzyme function and supports the "swinging arm" model in human ACCs.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.1-26
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• 1993

The purpose of this study was to investigate the effect of acid etching on the surface appearance and fracture toughness of five glass ionomer cements. Five kinds of commercially available glass ionomer cements including chemical curing filling type, chemical curing lining type, chemical curing metal reinforced type, light curing tilling type and light curing lining type were used for this study. The specimens for SEM study were fabricated by treating each glass ionomer cement with either visible light curing or self curing after being inserted into a rubber mold (diameter 4mm, depth 1mm). Some of the specimens were etched with 37% phosphoric acid for 0, 15, 30, 60, go seconds, at 5 minutes, 1 hour and 1 day after mixing of powder and liquid. Unetched ones comprised the control group and the others were the experimental groups. The surface texture was examined by using scanning electron microscope at 20 kV. (S-2300, Hitachi Co., Japan). The specimens for fracture toughness were fabricated by curing of each glass ionomer cement previously inserted into a metal mold for the single edge notch specimen according to the ASTME399. They were subjected to a three-point bend test after etching for 0, 30, 60, and 90 seconds at 5 minutes-, 1 hour-and 1 day-lapse after the fabrication of the specimens. The plane strain fracture toughness ($K_{IC}$) was determined by three-point bend test which was conducted with cross-head speed of 0.5 mm/min using Instron universal testing machine (Model No. 1122) following seven days storage of the etched specimens under $37^{\circ}C$, 100% humidity condition. Following conclusions were drawn. 1. In unetched control group, crack was present, but the surface was generally smooth. 2. Deterioration of the surface appearance such as serious dissolving of gel matrix and loss of glass particles occured as the etching time was increased beyond 15 s following Immediate etching of chemical curing type of glass ionomer cements. 3. Etching after 1 h, and 1 d reduced surface damage, 15 s, and 30s etch gave rough surface appearance without loss of glass particle of chemical curing type of glass ionomer cements. 4. Light curing type glass ionomer cement was etched by acid, but there was no difference in surface appearances according to various waiting periods. 5. It was found that the value of plane stram fracture toughness of glass ionomer cements was highest in the light curing filling type as $1.79\;MNm^{-1.5}$ followed by the light curing lining type, chemical curing metal reinforced type, chemical curing filling type and chemical curing lining type. 6. The value of plane stram fracture toughness of the chemical curing lining type glass ionomer cement etched after 5 minutes was lower than those of the cement etched after 1 hour or day or unetched (P < 0.05). 7. Light curing glass ionomer cement showed Irregular fractured surface and chemical curing cement showed smooth fractured surface.

• 한국재료학회지
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• 제19권1호
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• pp.28-32
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• 2009

Silicon carbide (SiC) is a promising material for power device applications due to its wide band gap (3.26 eV for 4H-SiC), high critical electric field and excellent thermal conductivity. The Schottky barrier diode is the representative high-power device that is currently available commercially. A field plate edge-terminated 4H-SiC was fabricated using a lift-off process for opening the Schottky contacts. In this case, Ni/Ti dual-metal contacts were unintentionally formed at the edge of the Schottky contacts and resulted in the degradation of the electrical properties of the diodes. The breakdown voltage and Schottky barrier height (SBH, ${\Phi}_B$) was 107 V and 0.67 eV, respectively. To form homogeneous single-metal Ni/4H-SiC Schottky contacts, a deposition and etching method was employed, and the electrical properties of the diodes were improved. The modified SBDs showed enhanced electrical properties, as witnessed by a breakdown voltage of 635 V, a Schottky barrier height of ${\Phi}_B$=1.48 eV, an ideality factor of n=1.04 (close to one), a forward voltage drop of $V_F$=1.6 V, a specific on resistance of $R_{on}=2.1m{\Omega}-cm^2$ and a power loss of $P_L=79.6Wcm^{-2}$.

• 한국문헌정보학회지
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• 제52권1호
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• pp.259-283
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• 2018

본 연구는 고전적 정리 번역서의 향후 출판 방향 모색과 관련하여 출판 방식의 변화와 현황 및 고전적 정리 번역서의 출판 형태에 대한 전문가와 일반이용자의 인식 차이를 알아보기 위한 목적으로 수행되었다. 이를 위해 일반적인 종이책과 전자책의 이용에 관한 국내외 관련 연구를 분석하고 국내 주요 기관의 고전적 정리 번역서 출판 현황을 조사하였으며, 한국고전번역원의 메일링리스트를 활용해 전문가와 일반이용자를 대상으로 설문조사를 실시하였다. 연구 결과 전자책은 종이책을 완벽하게 대체하는 매체로 간주되기는 어려우며, 이용자의 다양한 요구를 충족시킬 수 있도록 당분간 종이책과 전자책의 병행이 타당한 것으로 분석되었다. 특히 설문조사 결과에서는 종이책과 전자책의 개인적 사용가치, 소장가치, 가독성에 대한 인식에 있어서 일반이용자와 전문가 집단 간에 유의한 차이가 있는 것으로 확인되었다. 도서관이나 관련 기관에서의 보존가치에 대한 평가에서는 종이책에 대한 집단 간 유의한 차이는 확인되었으나 전자책의 경우에는 집단 간 의미있는 차이가 없었다. 또한 학술 연구나 번역 목적으로 이용되는 경우 종이책 형태의 고전적 정리 번역서가 전자책에 비해 더 선호되며, 온라인을 통한 이용에 있어서는 전자책보다 데이터베이스를 더 많이 선호하는 것으로 나타났다. 고전적 정리 번역서의 전자책 구현을 위해서는 고전적의 특수성과 상징성을 고려할 필요가 있으며, 또한 기술적으로 모든 환경에서 이용이 가능한 표준화된 플랫폼을 고려할 필요가 있는 것으로 분석되었다.

• 한국초지조사료학회지
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• 제34권1호
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• pp.9-14
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• 2014

하천부지에서 이탈리안 라이그라스(IRG)와 월년생 두과작물을 혼파하여 사초 생산성과 토양 특성을 조사하였다. 안산천 하천부지에서는 이탈리안 라이그라스와 헤어리베치의 혼파조합이 다른 조합보다 생초, 건물 및 수량이 가장 많았다. 이탈리안 혼파조합의 수확 시 건물률도 헤어리베치 조합이 가장 높았다. 혼파조합의 사료가치 비교에서 헤어리베치 조합이 조단백질 함량은 높았으나 TDN 및 비섬유성탄수화물(NFC) 함량은 다른 처리구에 비하여 낮았다. 따라서 질소 고정능력이 우수한 헤어리베치 조합이 다른 조합보다 토양의 전질소(TN) 함량이 높았다. 반면 토양의 유기물 함량은 유채 조합이 가장 높았으며, 토양의 유효인 산 함량은 크림손 클로버 조합이 높았다. 토양의 CEC 함량은 이탈리안 라이그라스와 헤어리베치 조합은 우수하였다. 이상의 결과를 종합해 볼 때 비료를 시용하지 못하는 하천변에서 월동 사료작물을 재배할 때 이탈리안 라이그라스와 헤어리베치의 혼파조합이 다른 혼파조합보다 사초생산성이 높아 토양의 질소와 인 제거에 의한 하천 수질 개선에 효과가 좋은 것으로 판단되었다.

• 대한지역사회영양학회지
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• 제8권2호
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• pp.181-191
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• 2003

The purpose of this study was to investigate the dietary habits, the nutritional knowledge and the consumption patterns of convenience foods of 618 university students located in the Gwangju area, from November twentieth to November thirtieth, 2002. The subjects included 301 males (48.7%) and 317 females (51.3%). This survey was conducted using a self-administered questionnaire. The percentage of students who were underweight, normal and overweight based on their body mass index (BMI) was 3.7, 88.0 and 8.3 far the males, and 29, 71 and 0 for the females, respectively. Most students (73.8%) skipped breakfast. This was because of lack of time (65.1%) of the cases. Self-reported eating habit problems were eating irregular meal (52.4%), overeating (21%), prejudiced meal (12.4%) and skipping meal (7.4%). The type of favorite snack was biscuit (31.9%) and cup Ramyon (31.9%). The rates of alcohol drinking in male and female students were 88.0% and 85.8% respectively, and the rates of smoking were 35.9% and 28% respectively. Males ate fiequently cup Ramyon (2.08 $\pm$ 2.95), fries (pork cutlet, fried potato) (1.91 $\pm$ 2.58), Ramyon (1.81 $\pm$ 3.00) and kimbab (1.70 $\pm$ 3.17) more frequently, while females ate kimbab (2.25 $\pm$ 3.26), cup Ramyon (1.89 $\pm$ 2.09), fries (pork cutlet, fried potato) (1.77 $\pm$ 2.67), Ramyon (1.46 $\pm$ 1.1.95) and fish paste (1.45 $\pm$ 2.22) more frequently. The nutritional knowledge score was higher in females than in males. The mean consumption patterns of convenience foods of students living in home were lower than that of students living in dormitory and boarding w/cooking. When the amount of pocket money available and the body mass index increased and the nutritional knowledge level was low, the mean consumption of convenience foods increased. The mean consumption of convenience foods correlated negatively with nutritional knowledge (p < 0.01). Therefore, nutritional education for university students is needed so as to improve their health and nutritional education program should be developed to meet the various needs of these students. (Korean J Community Nutrition 8(2) : 181~191, 2003)

• 방사선산업학회지
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• 제6권1호
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• pp.31-40
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• 2012

There are two methods to fabricate the readout electronic to a large-area CMOS image sensor (LACIS). One is to design and manufacture the sensor part and signal processing electronics in a single chip and the other is to integrate both parts with bump bonding or wire bonding after manufacturing both parts separately. The latter method has an advantage of the high yield because the optimized and specialized fabrication process can be chosen in designing and manufacturing each part. In this paper, LACIS chip, that is optimized design for the latter method of fabrication, is presented. The LACIS chip consists of a 3-TR pixel photodiode array, row driver (or called as a gate driver) circuit, and bonding pads to the external readout ICs. Among 4 types of the photodiode structure available in a standard CMOS process, $N_{photo}/P_{epi}$ type photodiode showed the highest quantum efficiency in the simulation study, though it requires one additional mask to control the doping concentration of $N_{photo}$ layer. The optimized channel widths and lengths of 3 pixel transistors are also determined by simulation. The select transistor is not significantly affected by channel length and width. But source follower transistor is strongly influenced by length and width. In row driver, to reduce signal time delay by high capacitance at output node, three stage inverter drivers are used. And channel width of the inverter driver increases gradually in each step. The sensor has very long metal wire that is about 170 mm. The repeater consisted of inverters is applied proper amount of pixel rows. It can help to reduce the long metal-line delay.

• 한국태양에너지학회 논문집
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• 제31권2호
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• pp.82-88
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• 2011

The artificial increase in the solar intensity incident on solar cells using lenses or mirrors can allow solar cells to generate equivalent power with a lower cost. There are two types of concentration optics for solar energy conversion. One is to use mirrors, and the other is to use Fresnel lenses. The gains that can be achieved with a Fresnel lens or a parabolic mirror are compared. The result showed the gains are comparable and the two configurations were developed competitively. In application areas of Fresnel lenses as solar concentrators, several variations of design were devised and tested. Some PV systems still use commercially available flat Fresnel lenses as concentrators. A convex linear Fresnel lens to improve the concentration ratio and the efficiency is devised and flat linear Fresnel lens in thermal energy collection is utilized. In this study, we designed and optimized flat Fresnel lens and the 'light pipe' to develop 500X concentrated solar PV system. In the process, we compare the transmission efficiencies according to groove types. We performed rigorous ray tracing simulation of the flat Fresnel lenses. The computer aided simulation showed the 'grooves in case' has the better efficiency than that of 'grooves out case'. Based on the ray-trace results we designed and manufactured sample Fresnel lenses. The optical performance were measured and compared with ray-trace results. Finally, the optical efficiency was measured to be above 75%. All the design and manufacturing were performed based on that InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. Field test will be made and analyzed in the near future.

• 한국토양비료학회지
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• 제39권6호
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• pp.334-338
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• 2006

호남평야지 논토양의 대표토양인 전북통에서 벼 담 수직파재배시 토양물리성 개선과 진단시비로 쌀 안정생산을 위한 토양관리기술을 확립하고자 관행, 진단시비, 진단시비+퇴비+규산, 진단시비(LCU 70%)+심경, 진단시비(LCU 70%)+심토파쇄, 무질소구 등 6처리를 하여 2년간(1999~2000) 시험한 결과를 요약하면 다음과 같다. 시험후 심토에서 물리성은 관행에 비하여 경도, 용적밀도, 고상이 낮아지고 공극률이 증가되었으며 그 정도는 심토파쇄>심경 순으로 양호하였다. 시험 후 토양의 화학성은 관행에 비하여 진단시비구, 완효성비료(LCU 70%) 시용 및 토양물리성 개선구에서 유기물함량, 규산함량 등이 증가하였다. 시비질소의 토양중 $NH_4-N$ 농도는 5엽기까지는 심경구에서 가장 높게 발현되었으며 관행 대비 LCU 70% 시용구에서 성숙기까지 발현량이 많았다. 시비질소의 흡수량은 관행에 비하여 진단시비(LCU 70%)+심경, 심토파쇄구에서 많았고 질소이용률도 높았다. 쌀수량은 관행($5.22Mg\;ha^{-1}$)대비 진단시비(LCU 70%)+심토파쇄구에서 8%, 진단시비(LCU 70%)+심경구에서 4% 증수되었으며, 증수요인은 $m^2$당 입수가 많고 등숙률이 높았던 것에 기인한 것으로 사료된다.