• 한국분말재료학회지
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• 제22권6호
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• pp.426-431
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• 2015

Microstructural examination of the Nb-Si-B alloys at Nb-rich compositions is performed. The Nb-rich corner of the Nb-Si-B system is favorable in that the constituent phases are Nb (ductile and tough phase with high melting temperature) and $T_2$ phase (very hard intermetallic compound with favorable oxidation resistance) which are good combination for high temperature structural materials. The samples containing compositions near Nb-rich corner of the Nb-Si-B ternary system are prepared by spark plasma sintering (SPS) process using $T_2$ and Nb powders. $T_2$ bulk phase is made in arc furnace by melting the Nb slug and the Si-B powder compact. The $T_2$ bulk phase was subsequently ball-milled to powders. SPS is performed at $1300^{\circ}C$ and $1400^{\circ}C$, depending on the composition, under 30 MPa for 600s, to produce disc-shaped specimen with 15 mm in diameter and 3 mm high. Hardness tests (Rockwell A-scale and micro Vickers) are carried out to estimate the mechanical property.

• 콘크리트학회지
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• 제8권6호
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• pp.235-243
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• 1996

콘크리트의 역학적거동은 다양한 종류의 균열의 발생과 전파에 의하여 영향을 받는다. 최근 고성능 콘크리트의 개발이 이루어지면서 계면파괴와 계면역에서의 균열양상에 대한 연구가 중요한 분야로 부각되고 있다. 탄성이며 균질한 재료에 적용되는 균열전파에 대한 규준은 계면역에서 균열이 진전하는 경우는 유효하지 않으며 이 경우에는 콘크리트에서 균열전파를 예측하기 위하여 구성재료들의 파괴인성과 그들 사이 계면의 파괴인성의상대적인 크기를 고려하여야 한다. 본 논문에서는 계면균열선단에서 계면파괴역학변수인 에너지해방률과 하중위상각을 수치해석방법을 이용하여 구하는 방법과 계면에서의 균열전파의 예측을 위한 에너지해방률에 기초를 둔 파괴규준을 제안하였다. 계면역에서의 균열양상을 조사하기 위하여 계면균열을 가진 이상복합모델에 대한 실험과 수치해석연구를 수행하였으며 대체적으로 실험결과와 규준을 이용하여 예측한 결과가 서로 일치하는 결과를 얻었다.

• 한국측량학회지
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• 제36권5호
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• pp.343-353
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• 2018

Ocean tides in Antarctica are not well constrained mostly due to the lack of tidal observations. Especially, tides underneath and around ice shelves are uncertain. InSAR (Interferometric Synthetic Aperture Radar) data has been used to observe ice shelf movements primarily caused by ocean tides. Here, we demonstrate that it is possible to estimate tidal constituents underneath the Sulzberger ice shelf, West Antarctica, solely using ERS-1/2 tandem mission DInSAR (differential InSAR) observations. In addition, the tidal constituents can be estimated in a high-resolution (~200 m) grid which is beyond any tidal model resolution. We assume that InSAR observed ocean tidal heights can be derived after correcting the InSAR data for the effect of atmospheric loading using the inverse barometric effect, solid earth tides, and ocean tide loading. The ERS (European Remote Sensing) tandem orbit configuration of a 1-day separation between SAR data takes diminishes the sensitivity to major tidal constituents including $K_1$ and $S_2$. Here, the dominant tidal constituent $O_1$ is estimated using 8 differential interferograms underneath the Sulzberger ice shelf. The resulting tidal constituent is compared with a contemporary regional tide model (CATS2008a) and a global tide model (TPXO7.1). The InSAR estimated tidal amplitude agrees well with both models with RMS (root-mean-square) differences of < 2.2 cm and the phase estimate corroborating both tide models to within $8^{\circ}$. We conclude that fine spatial scale (~200 m) Antarctic ice shelf ocean tide determination is feasible for dominant constituents using C-band ERS-1/2 tandem mission InSAR.

• Molecules and Cells
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• 제41권2호
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• pp.73-82
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• 2018

Cancer preventive activities of green tea and its main constituent, (-)-epigallocatechin gallate (EGCG) have been extensively studied by scientists all over the world. Since 1983, we have studied the cancer chemopreventive effects of EGCG as well as green tea extract and underlying molecular mechanisms. The first part of this review summarizes groundbreaking topics with EGCG and green tea extract: 1) Delayed cancer onset as revealed by a 10-year prospective cohort study, 2) Prevention of colorectal adenoma recurrence by a double-blind randomized clinical phase II trial, 3) Inhibition of metastasis of B16 melanoma cells to the lungs of mice, 4) Increase in the average value of Young's moduli, i.e., cell stiffness, for human lung cancer cell lines and inhibition of cell motility and 5) Synergistic enhancement of anticancer activity against human cancer cell lines with the combination of EGCG and anticancer compounds. In the second part, we became interested in cancer stem cells (CSCs). 1) Cancer stem cells in mouse skin carcinogenesis by way of introduction, after which we discuss two subjects from our review on human CSCs reported by other investigators gathered from a search of PubMed, 2) Expression of stemness markers of human CSCs compared with their parental cells, and 3) EGCG decreases or increases the expression of mRNA and protein in human CSCs. On this point, EGCG inhibited self-renewal and expression of pluripotency-maintaining transcription factors in human CSCs. Human CSCs are thus a target for cancer prevention and treatment with EGCG and green tea catechins.

• Journal of Photoscience
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• 제9권2호
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• pp.367-369
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• 2002

Chlorophyll (ChI) a' is the Cl3$^2$-epimer of ChI a which is the constituent of P700, the primary electron donor of Photosystem (PS) I, of a thrmophilic cyanobacterium, Synechococcus elongatus, whose structure was recently determined by X-ray crystallography. To determine whether PS I of diverse oxygenic photosynthetic organisms universally contain one molecule of ChI a ’, pigment compositions of thylakoid membranes and PS I complexes isolated from cyanobacteria, green algae, red algae and higher plants were determined by reversed-phase HPLC. The results show that involvement of one ChI a'molecule in PS I is the universal feature for Chi a-based PS I of oxygenic photosynthetic organisms.

• 한국세라믹학회지
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• 제41권8호
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• pp.582-587
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• 2004

수산화아파타이트(HAp) 및 P-인산3칼슘($\beta$-TCP)으로 구성되는 2상 인산칼슘염(BCP)을 고상반응법으로 합성하고, 이를 상압 및 autoclave를 이용한 고압에서 수열반응 시킴으로써 응집입자의 미세화를 시도하였다. 이 과정에서 일어나는 결정 상 및 화학조성, 구성상의 상대적인 양, 비표면적, 미세구조의 변화에 미치는 공정조건의 영향을 XRD, FT-IR, 질소흡착에 의한 BET법, SEM을 이용하여 검토하였다.

• Journal of Applied Biological Chemistry
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• 제58권4호
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• pp.303-309
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• 2015

${\gamma}$-Aminobutyric acid (GABA) content in fermented plant products and their main plant materials (aerial part of Acanthopanax sessiliflorus, fruit of Crataegus pinnatifida, and whole plant of Morus alba) was determined by high-performance liquid chromatography. GABA was quantified using a reverse-phase column with a gradient elution program (water:acetonitrile =90:10 to 0:100 for 40 min). UV detection was conducted at 280 nm. GABA content was measured in fermented plant products (15.07 mg/g), aerial part of A. sessiliflorus (4.49 mg/g), fruit of C. pinnatifida (10.59 mg/g), and whole plant of M. alba (2.31 mg/g). The presence of GABA in fermented plant products, including A. sessiliflorus, C. pinnatifida, and M. alba is important in industrial application for health supplements.

• 전자공학회논문지C
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• 제35C권2호
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• pp.65-70
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• 1998

In this paper, we will to check and to correct mis-recognized word using Eojeol information. First, we divided into 16 classes that constituents in a Eojeol after we analyzed Korean statement into Eojeol units. Eojeol-Constituent state diagram constructed these constitutents, find the Left-Right Connectivity Information. As analogized the speech of connectivity information, reduced the number of cadidate words and restricted case of morphological analysis for mis-recognition Eojeol. Then, we improved correction speed uisng heuristic information as the adjacency information for Eojeol each other. In the correction phase, construct Reverse-Order Word Dictionary. Using this, we can trace word dictionary regardless of mis-recongnition word position. Its results show that improvement of recognition rate from 97.03% to 98.02% and check rate, reduction of chadidata words and morpholgical analysis cases.

• Asian-Australasian Journal of Animal Sciences
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• 제1권2호
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• pp.99-106
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• 1988

A high performance liquid chromatographic procedure is described for the direct determination of the picomole amount of palmitoyl-Coenzyme A and stearoyl-Coenzyme A, using a stainless steel column packed with C-18 derivatized porous silica ($5{\mu}m$), an isocratic elution with a mixture of 33 mM $KH_2PO_4$/acetonitrile as a mobile phase and a UV detector. The long-chain acyl-Coenzyme A esters were determined in incubated microsomal fractions of a bovine liver to demonstrate the utility of this method for monitoring acyl-CoA synthesis in biological samples. The reaction rate of palmitate was higher than that of stearate. After a 60 minute incubation period, the generated amount of palmitoyl-Coenzyme A and stearoyl-Coenzyme A were approximately 70 and 20 n mol/mg micresomal protein, respectively. The advantage of this method are in that no decomposition of the CoA esters is involved, while the constituent molecular species is detected.

• 한국해양공학회지
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• 제16권2호
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• pp.6-9
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• 2002

The long-term monthly variations of tide with tidal harmonic analysis in Pusan Harbour are investigated. The present spring tidal range decreased 1.4 cm and the variation of phase lag increased than 1974. The high and low water level of yearly mean sea level is show during the February to March and August to September, respectively. It is important to note that the larger lunar elliptic N2 is large in comparison with lunisolar diurnal K1 and principal lunar diurnal O1. The ratios (Correction Factors) of monthly mean sea level and the main 4 tidal constituents are evaluated to correct the shortly (monthly) observed tide for the design of harbour facilities.