• Journal of Embryo Transfer
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• v.12 no.3
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• pp.229-246
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• 1997

Implantation is a most important biological process during pregnancy whereby conceptus establishes its survival as well as maintenance of pregnancy. During the periimplantation period, both uterine endometriurn and conceptus synthesize and secrete a host of growth factors and cytokines which mediate the actions of estrogen and /or progesterone and also exert their steroid-independent actions. Growth factors expressed by the materno-conceptal unit en masse have important roles in cell migration, stimulation or inhibition of cell proliferation, cellular differentiation, maintenance of pregnancy and materno-conceptal communications in an autorcrine /paracrine manner. The present review focuses on the role of the intrauterine IGF system during periimplantation conceptus development. The IGF system comprises of IGF- I and IGF- II ligands, types I and II IGF receptors and six or more IGF-binding proteins(IGFBPs). IGFs and IGFBPs are expressed and secreted by uterine endometrium with tissue, pregnancy stage and species specificities under the influence of estrogen, progesterone and other growth factor(s). Conceptus also synthesizes components of the IGF system beginning from a period between 2-cell and blastocyst stages. Maternal IGFs are utilized by both maternal and conceptal tissues; conceptus-derived growth factors are believed to be taken up primarily by conceptus. IGFs enhance the development of both maternal and conceptal compartments in a wide range of biological processes. They stimulate proliferation and differentiation of endometrial cells and placental precursor cells including decidual transformation from stromal cells, placental formation and the synthesis of some steroid and protein hormones by differentiated endometrial cells or placenta. It is also well-documented in a number of experimental settings that both IGFs stimulate preimplantation embryo development. In slight contrast to these, prenatal mice carrying a null mutation of IGF and /or IGF receptor gene do not exhibit any apparent growth retardation until after implantation. Reason (s) for this discrepancy between the knock-out result and the in vitro ones, however, is not known. IGFBPs, in general, are believed to inhibit IGF action within the materno-conceptal unit, thereby allowing endometrial stromal cell differentiation as well as dampening ex cessive placental invasion into maternal tissue. There is evidence, however, indicating that IGFBP can enhance IGF action depending on environrnental conditions perhaps by directioning IGF ligand to the target cell. There is also a third possibility that certain IGFBPs and their proteolytic fragments may have their own biological activities independent of the IGF. In addition to IGFBPs, IGFBP proteases including those found within the uterine tissue or lumen are thought to enhance IGF bioavailability by degrading their substrates without affecting their bound ligand. In this regard, preliminary results in early pregnant pigs suggest that a partially characterized IGFBP protease activity in uterine luminal fluid enhances intrauterine IGF bioavailability during conceptus morphological development. In summary, a number of in vitro results indicate that IGFs stimulates the development of the rnaterno-conceptal unit during the periimplantation period. IGFBPs appear to inhibit IGF action by sequestering their ligands, whereas IGFBP proteases are thought to enhance intrauterine bioavailability of IGFs. Much is remaining to be clarified, however, regarding the roles of the individual IGF system components. These include in vivo evidence for the role of IGFs in early conceptus development, identification of IGF-regulated genes and their functions, specific roles for individual IGFBPs, identification and characterization of IGFBP proteases. The intrauterine IGF club house thus will be paying a lot of attention to forthcoming results in above and other areas, with its door wide-open!

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.58-63
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• 1980

Three seasme cultivars were compared in viewpoints of ripening developments and yielding potentials per plant after the flowering date. On this study, timely ripening and yielding developments were checked separately with capsules and seeds which outcome from the flowers labelled at 30th of July, the maximum flowering stage. Mostly, size and dry weight developments were estimated and the results obtained are as follows; 1. "Early Russian" was recognized as an ideal cultivar with large sized capsule and high lipid contents. However, under the enough ripening periods and ripening conditions (temperature, lights, and nutrients, etc.), the cultivar has weakness on the capsule developments which is competed with seed developments as mean of sink concern. 2. "Suwon 5" was a high yielding cultivar under the proper ripening weather (F. ex. southern districts), but under the unfavorable ripening conditions the cultivar may have weakness of rapid yield decrease by comparatively later formation of seed weight than the capsule. Especially the cultivar has the very ripening characteristics adapting to southern districts which have higher temperature and later low limiting stage for sesame ripening. 3. "Black colored native" seasme cultivar showed lower yielding and later ripening characteristics among others. Also, under the unfavorable ripening conditions, the cultivar has the weakness of yield decrease. Even under the favorable conditions, the cultivar will still have the weakness which is not able to increase in yield, because the capsule development would be finished in size and dry weight too early to accept the later developments of seeds.e later developments of seeds.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1583-1590
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• 2006

T4 endonuclease V (T4 endo V) [EC 3. 1. 25. 1], found in bacteriophage T4, is responsible for excision repair of damaged DNA. The enzyme possesses two activities: a cyclobutane pyrimidine dimer DNA glycosylase (CPD glycosylase) and an apyrimidic/apurinic endonuclease (AP lyase). T4 denV (414 bp cDNA) encoding T4 en do V (138 amino acid) was synthesized and expressed using either an expression vector, pTriEx-4, in E. coli or a baculovirus AcNPV vector, pBacPAK8, in insect cells. The recombinant His-Tag/T4 endo V (rHis-Tag/T4 endo V) protein expressed from bacteria was purified using one-step affinity chromatography with a HiTrap Chelating HP column and used to make rabbit anti-His-Tag/T4 endo V polyclonal antibody for detection of recombinant T4 endo V (rT4 endo V) expressed in insect cells. In the meantime, the recombinant baculovirus was obtained by cotransfection of BacPAK6 viral DNA and pBP/T4 endo V in Spodoptera frugiperda (Sf21) insect cells, and used to infect Sf21 cells to overexpress T4 endo V protein. The level of rT4 endo V protein expressed in Sf21 cells was optimized by varying the virus titers and time course of infection. The optimal expression condition was set as follows; infection of the cells at a MOI of 10 and harvest at 96 h post-infection. Under these conditions, we estimated the amount of rT4 endo V produced in the baculovirus expression vector system to be 125 mg/l. The rT4 endo V was purified to homogeneity by a rapid procedure, consisting of ion-exchange, affinity, and reversed phase chromatographies, based on FPLC. The rT4 endo V positively reacted to an antiserum made against rHis-Tag/T4 endo V and showed a residual nicking activity against CPD-containing DNA caused by UV. This is the first report to have T4 endo V expressed in an insect system to exclude the toxic effect of a bacterial expression system, retaining enzymatic activity.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.5
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• pp.459-466
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• 2016

Adipogenic differentiation of mesenchymal stem cells (MSCs) is critical for metabolic homeostasis and nutrient signaling during development. However, limited information is available on the pivotal modulators of adipogenic differentiation of MSCs. Adaptor protein Lnk (Src homology 2B3 [SH2B3]), which belongs to a family of SH2-containing proteins, modulates the bioactivities of different stem cells, including hematopoietic stem cells and endothelial progenitor cells. In this study, we investigated whether an interaction between insulin-like growth factor-1 receptor (IGF-1R) and Lnk regulated IGF-1-induced adipogenic differentiation of MSCs. We found that wild-type MSCs showed greater adipogenic differentiation potential than $Lnk^{-/-}$ MSCs. An ex vivo adipogenic differentiation assay showed that $Lnk^{-/-}$ MSCs had decreased adipogenic differentiation potential compared with wild-type MSCs. Interestingly, we found that Lnk formed a complex with IGF-1R and that IGF-1 induced the dissociation of this complex. In addition, we observed that IGF-1-induced increase in the phosphorylation of Akt and mammalian target of rapamycin was triggered by the dissociation of the IGF-1R-Lnk complex. Expression levels of a pivotal transcription factor peroxisome proliferator-activated receptor gamma ($PPAR-{\gamma}$) and its adipogenic target genes (LPL and FABP4) significantly decreased in $Lnk^{-/-}$ MSCs. These results suggested that Lnk adaptor protein regulated the adipogenesis of MSCs through the $IGF-1/Akt/PPAR-{\gamma}$ pathway.

• Journal of Korea Technology Innovation Society
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• v.12 no.4
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• pp.819-839
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• 2009

Proposed increases to the government's R&D budget should be discussed based on merits of meeting efficiency and effectiveness criteria. The evaluation of the national R&D budget and related programs are performed in two areas: a system of R&D budget coordination and allocation, and a system of R&D program performance. This paper mainly focuses on the operational areas of R&D budget evaluation system with a focus on their impact to efficiency and effectiveness. The core view point for a R&D budget evaluation system involves two directions: Firstly, to detail the relationships between the later stage (ex. post) activities such as, program survey, analysis, and program performance evaluation, with the budget evaluation. Secondly, to critically oversee all R&D coordination procedures with a different perspective. Budgeting is generally known as a serial process of policy making, planning and executing. It is highly desirable for the budget to be allocated to, and spent by, specific programs as planned, and that each plan be aligned with a specific policy. As such, a strong relevance between the program structure and budget code system is integral to successful execution. It should be performed using a decision making system which closely examines the link between policy and budget. It is also recommended that systematic relationships be maintained among budget coordination and allocation, performance evaluations of policy and program levels, and program survey and analysis system, and that their operational schedule should be reviewed comprehensively as a one integrated system. The National Science and Technology Council is expected to play a major and practical role as the center of policy planning and should be supported by the objective and unbiased system which covers overall process from policy making to program evaluation. Finally, increased utilization of contents, timely program survey and analysis, and accurate of activity scheduling of budget coordination and allocation, and diligent program performance evaluation all contribute towards a more efficient and effective overall evaluation system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1982-1987
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• 2011

In this study, we proposed a new method that can estimate viscosity curves of unknown samples or high viscous resins like LFT(Long Fiber Thermoplastics). First, we built the system that could detect the pressure of melt during filling the cavity in a mold. It consists of both pressure sensors which are installed in a mold and the Kit which can convert analog signal to digital signal. The kit measures the melt pressure in mold cavity. We could also simulate the cavity pressure during filling process with commercialized CAE softwares(ex, Moldflow). If the viscosity data in CAE Database were correct, the simulated pressure profile coincided with the measured one. According to our proposed algorithm, we obtained correct viscosity data by iterating the process of comparing the simulated profile with the measured one until both coincided each other. In order to verify this algorithm, we selected well-defined PP resin and concluded that the experimental profile comply with the CAE profile. We could also estimate the optimized viscosity curves for PP-LFT by applying our method.

• The Korean Journal of Applied Statistics
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• v.30 no.1
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• pp.41-55
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• 2017

This study predicts the average scores of top 150 PGA golf players on 132 PGA Tour tournaments (2013-2015) using data mining techniques and statistical analysis. This study also aims to predict the Top 10 and Top 25 best players in 4 different playoffs. Linear and nonlinear regression methods were used to predict average scores. Stepwise regression, all best subset, LASSO, ridge regression and principal component regression were used for the linear regression method. Tree, bagging, gradient boosting, neural network, random forests and KNN were used for nonlinear regression method. We found that the average score increases as fairway firmness or green height or average maximum wind speed increases. We also found that the average score decreases as the number of one-putts or scrambling variable or longest driving distance increases. All 11 different models have low prediction error when predicting the average scores of PGA Tournaments in 2015 which is not included in the training set. However, the performances of Bagging and Random Forest models are the best among all models and these two models have the highest prediction accuracy when predicting the Top 10 and Top 25 best players in 4 different playoffs.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.113-113
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• 2000

직접천이형 wide band gap(3.4eV) 반도체중의 하나인 GaN를 청색 및 자외선 laser diode, 고출력 전자장비 등으로 응용하기 위해서는 낮은 접합저항을 갖는 Ohmic contact이 선행되어야 한다. 그러나 만족할만한 p-type GaN의 Ohmic contact은 아직 실현되고 있지 못하며, 이는 GaN와 접합 금속과의 구체적인 반응의 연구를 필요로 한다. 본 연구에서 앞서 Pt, Pt, Ni등의 late transition metal을 p-GaN에 접합시킨 결과 이들은 접합 당시 비교적 평탄하나 후열 처리과정에서 비교적 낮은 온도에서 기판과 열팽창계수의 차이로 인하여 평탄성을 잃어버리면서 barrier height가 증가한다는 사실을 확인하였다. 따라서 본 연구에서는 이러한 열적 불안정성을 극복하기 위하여 Ni과 Pd를 차례로 증착하고 가열하면서 interfacial reaction, film morphology, Fermi level의 움직임을 monchromatic XPS(x-ray photoelectron spectroscopy) 와 SAM(scanning Auger microscopy) 그리고 ex-situ AFM을 이용하여 밝히고자 하였다. 특히 후열처리에 의한 계면 반응에 수반되는 구성 금속원소 간의 합금현상과 금속 층의 평탄성이 밀접한 관계가 있다는 것을 확인하였다. 이러한 합금과정에서 나타나는 금속원소들의 중심 준위의 이동을 체계적으로 규명하기 위해서 Pd1-xNix와 Pd1-xGax 합금들의 표준시료를 arc melting method로 만들어 농도에 따른 금속원소들의 중심 준위의 이동을 측정하여, Pd/Ni/p-GaN 및 Ni/Pd/p-GaN 계에서 열처리 온도에 따른 interfacial reaction을 확인하였다. 그 결과 두 계가 상온에서 nitride 및 alloy를 형성하지 않고 고르게 증착되고, 열처리 온도를 40$0^{\circ}C$에서 $650^{\circ}C$까지 증가시킴에 따라 계면반응의 부산물인 metallic Ga은 증가하고 있으마 nitride는 여전히 형성되지 않는 것을 확인하였다. 증착당시 Ni이 계면에 있는 Pd/Ni/p-GaN의 경우에는 52$0^{\circ}C$까지의 열처리에 의하여 Ni과 Pd가 골고루 섞이고 그 평탄성도 유지되고 barier height의 변화도 없었다. 더 높은 $650^{\circ}C$ 가열에 의해서는 surface free energy가 작은 Ga의 활발한 편석 현상으로 인해 표면은 Ga이 풍부한 Pd-Ga의 합금층으로 덮이고, 동시에 작은 pinhole들이 발생하며 barrier height도 0.3eV 가량 증가하게 된다. 반면에 증착당시 Pd이 계면에 있는 Ni/Pd/p-GaN의 경우에는 40$0^{\circ}C$의 가열까지는 두 금속이 그들 계면에서부터 섞이나, 52$0^{\circ}C$의 가열에 의해 이미 barrier height가 0.2eV 가량 증가하기 시작하였다. 더 높은 $650^{\circ}C$가열에 의해서는 커다란 pinhole, 0.5eV 가량의 barrier height 증가, Pd clustering이 동시에 관찰되었다. 따라서 Ni과 Pd의 일함수는 물론 thermal expansion coefficient가 거의 같으며 surface free energy도 거의 일치한다는 점을 감안하면, 이렇게 뚜렷한 열적 안정성의 차이는 GaN와 contact metal과의 반응시작 온도(disruption onset temperature)의 차이에 기인함을 알 수 있었다. 즉 계면에서의 반응에 의해 편석되는 Ga에 의해 박막의 strain이 이완되면, pinhole 등의 박막결함이 줄어 들고, 이는 계면의 N의 out-diffusion을 방지하여 p-type GaN의 barrier height 증가를 막게 된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.205-205
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• 2013

테라헤르쯔(terahertz: THz)파는 0.1~10 THz 의 범위로 적외선과 방송파 사이에 광대역 주파수 스펙트럼을 차지하고 있으며 직진성, 투과성, 그리고 낮은 에너지 (meV)를 가지고 있어 비 파괴적이고 무해한 장점을 지니고 있다. Ti:sapphire laser와 같은 femto-pulse source 등이 많은 발전이 되어 현재 많은 연구와 발전이 이루어지고 있다. femto-pulse source를 이용한 THz 응용에서는 높은 저항, 큰 전자 이동도, 그리고 아주 짧은 전하수명의 기판을 요구하는데 저온에서 성장한 (low-temperature grown : LT) GaAs는 격자 내에 Gallium 자리에 Arsenic이 치환 하면서 AsGa antisite가 발생하여 전하수명을 짧아지는 것을 응용하여 가장 많이 이용되고 있다. 현재 THz 응용분야에서 보다 작고 가격경쟁력이 있는 광통신을 이용한 THz photomixer등이 활발히 연구 하고 있다. 광섬유 내에서 손실과 분산이 최소값을 가지는 부분이 1.55 ${\mu}m$ 부근이고 In0.53Ga0.47As 기판을 이용하였을 때 여기에 완벽하게 만족하게 된다. 하지만 LT-InGaAs 의 경우 AsGa antisite로 인하여 carrier lifetime은 짧아지지만 높은 n-type 전하밀도를 가지게 된다. 이때 Be을 doping하여 전하밀도를 보상하여 높은 저항을 유지해야 하는데 Be의 활성화를 위해서는 열처리를 필요로 한다. 하지만 열처리를 하면 carrier lifetime이 길어지기 때문에 carrier lifetime과 저항을 적절히 조율해야 한다. 이는 물질자체의 특성이기 때문에 InGaAs는 GaAs보다 낮은 amplitude와 짧은 cut-off frequency를 가진다. 본 연구에서는 보다 높은 저항을 얻기 위하여 molecular beam epitaxy를 이용하여 semi-insulating InP:Fe 기판위에 격자 정합된 InGaAs:Be/InAlAs multi quantum well (MQW)를 온도별 ($250{\sim}400^{\circ}C$), 주기별 (50~150)로 성장을 하였고 이때 InGaAs layer의 Be doping level은 $2{\times}1018\;cm^{-3}$, Ex-situ annealing은 $550^{\circ}C$에서 10분으로 고정 하였다. THz 발생 실험에서는 InGaAs/InAlAs MQW은 4000 pA로 1,000 pA를 가지는 InGaAs epilayer보다 4배 높은 전류 신호를 얻을 수 있었고 모든 샘플이 2 THz에서 cut-off frequency를 가지고 있었다. THz 검출 실험에서는 LT-InGaAs:Be epilayer LT-InGaAs:Be/InAlAs, HT-InGaAs/InAlAs 샘플이 각각 180, 9000, 12000 pA의 전류신호를 가지고 있었고 모든 샘플이 2 THz에서 cut-off frequency를 가지고 있었다. HT-InGaAs/InAlAs MQW를 이용한 검출실험에서는 InGaAs layer가 defect free이지만 LT-InGaAs:Be/ InAlAs MQW 보다 높은 전류 신호를 얻을 수 있었다. 이는 InAlAs layer가 저항만 높이는 것뿐만 아니라 carrier trapping layer로써의 역할도 하는 것으로 사료된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.131-131
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• 2013

A single-layer graphene has been uniformly grown on a Cu surface at elevated temperatures by thermally processing a poly(methyl methacrylate) (PMMA) film in a rapid thermal annealing (RTA) system under vacuum. The detailed chemistry of the transition from solid-state carbon to graphene on the catalytic Cu surface was investigated by performing in-situ residual gas analysis while PMMA/Cu-foil samples being heated, in conjunction with interrupted growth studies to reconstruct ex-situ the heating process. The data clearly show that the formation of graphene occurs with hydrocarbon molecules vaporized from PMMA, such as methane and/or methyl radicals, as precursors rather than by the direct graphitization of solid-state carbon. We also found that the temperature for vaporizing hydrocarbon molecules from PMMA and the length of time the gaseous hydrocarbon atmosphere is maintained, which are dependent on both the heating temperature profile and the amount of a solid carbon feedstock are the dominant factors to determine the crystalline quality of the resulting graphene film. Under optimal growth conditions, the PMMA-derived graphene was found to have a carrier (hole) mobility as high as ~2,700 cm2V-1s-1 at room temperature, superior to common graphene converted from solid carbon.