• 한국주조공학회지
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• 제9권6호
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• pp.483-489
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• 1989

In the stable eutectoid transformation of austenite in ductile cast iron, ferrite forms around the graphite spheroid. As carbon diffuses through the ferrite ring, the graphite spheroid must eularge and the ferrite ring must deform plastically to accomodate this growth. A model has been proposed to clarify this mechanism. The alloying effects of molybdenum, nickel and copper were studied in a series of heats cast into a range of casting section sizes. Regression analysis was used to illustrate the effects of alloying and cooling rate on the microstructure of ductile cast iron.

• 대한핵의학회지
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• 제36권4호
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• pp.209-223
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• 2002

By considering the biological properties of a tumor, it should be possible to realize better results in cancer therapy. PET imaging offers the opportunity to measure tumor growth non-invasively and repeatedly as an early assessment of response to cancer therapy. Measuring cellular growth instead of energy metabolism showed offer significant advantages in evaluating therapy. Thymidine and its derivative nucleoside compounds can be changed to mono, di- and tri- phosphate compounds by thymidine kinase and then be incorporated into DNA. Their bindings are increased in highly proliferating cells due to the high DNA synthesis rate. To evaluate cell proliferation, many kinds of thymidine and uridine derivatives have been labeled with positron emitter and radioactive iodine. Compared to radiopharmaceuticals which have radioisotope labeled base ring such as pyirmidine, the radiopharmacuticals which have radioisotope labeled sugar ring are more stable in vivo and have metabolic resistance. The biological properties such as DNA incorporation ratios are highly dependent on their chemical structures and metabolic processes. This overview describes synthesis of radiopharmaceuticals and their biological properties for imaging of tumor cell proliferation.

• ETRI Journal
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• 제26권4호
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• pp.332-343
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• 2004

One of the recent and most significant technical properties can be expressed as "digital convergence," which is helping lead the technical paradigm into a ubiquitous environment. As an initial trial of realizing a ubiquitous environment, the convergence between broadcasting and telecommunication fields is now on the way, where it is required to develop a scalable video coding scheme for one-source and multi-use media. Traditional scalable video coding schemes have, however, limitations for higher stable picture quality especially on the region of interest. Therefore, this paper introduces an adaptive scanning method especially designed for a higher regional-stable picture quality under a ubiquitous video coding environment, which can improve the subjective quality of the decoded video by most-preferentially encoding, transmitting, and decoding the top-priority image information of the region of interest. Thus, the video can be more clearly visible to users. From various simulation results, the proposed scanning method in this paper can achieve an improved subjective picture quality far better than the widely used raster scan order in conventional video coding schemes, especially on the region of interest, and without a significant loss of quality in the left-over region.

• 한국안전학회지
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• 제11권4호
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• pp.84-89
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• 1996

The Oxidation of aflatoxin $G_1$ ($AFG_1$) with ozone in chloroform solvent gave the stable ozonide into ozonization of the double bond in the terminal furan ring, and this reaction have been carried out for 3hr at -78. 5$^{\circ}C$. The chloroform solvent was removed in a stream of nitrogen and the residue was separated by elution chromatography(EC). The structure of this compound have been identified by using MS, $^1H-NMR$, $^l3C-NMR$ and I. R spectroscopy, respectively. This compound was formed the normal stable AFG$_1$-ozonide into spontaneous rearrangement after unstable ozonide according to sigmatropic rearrange ment dependent upon cyclo addition by ozone.

• 전자통신동향분석
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• 제34권5호
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• pp.91-98
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• 2019

Optical frequency comb generators have been investigated as a signal source capable of generating highly stabilized ultrafast pulse lasers. The precise control of the optical frequency comb spacing by RF clock signals has led to a revolutionary paradigm shift in the precise measurement of time and frequency. Optical frequency combs also have advantages such as stable frequency spacing, stable number of lines, and robustness. Owing to these characteristics, optical frequency combs have been applied to the fields of high precision optical clock, communication, spectroscopy, waveform generation, and astronomy. In this article, we introduce the properties (i.e., generation methods, advantages, and so on) of various optical frequency combs, and discuss the expected future technological trends and applications.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 동계연구발표회 논문개요집
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• pp.186-187
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• 2002

Recently, there has been much interest in magnetic thin film patterned in submicron scale because of possible ultrahigh density storage media or logical device applications [1-3]. Various geometries such as rectangle, circle, ring and ellipse type dots have been studied to find the shape showing stable switching behavior from repeated cycles. However, rectangle and circle types may not be suitable for device applications because they have two uncontrollable different magnetization reversal modes: C state and S state, resulting in different coercivity and irreproducible switching[4]. (omitted)

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.531-534
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• 1999

Irradiation (300 nm UV light) of dibenzoylmethane and 1,4-naphthoquinone in dichloromethane gave 1,5-dike-tone as the major product, along with β-hydroxyketone as the minor product. Anthraquinone and anthrone also added photochemically to dibenzoylmethane to give 1,5-diketones as the major products. In contrast, tetrahalo-1,4-benzoquinones added to dibenzoylmethane to give two types of 1,5-diketones via oxetane and cyclobutane intermediates. Comparison of the potential energy values of the photoproducts reveals that the 1,5-diketones are more stable than the corresponding oxetanes or cyclobutanes due to the ring-strain of the bicyclic compounds.

• Bulletin of the Korean Chemical Society
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• 제14권5호
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• pp.631-635
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• 1993

The polarizability and the transition state energy of a cephalosporin are assumed to be theoretical indices of the permeability through the outer membrane and of reactivity of ${\beta}$ -lactam ring with penicillin binding proteins, respectively, in Gram-negative bacteria. They are computed by AM1 method and used as variables of quantitative structure-activity relationship study. The results justify quadratic dependence of the activity on the variables. The intersection of difference volumes between $\beta-lactamase$ stable cephalosporins and unstable ones manifests that the steric hindrance of 7-side chain is responsible for the ${\beta}$ -lactamase stability.

• Bulletin of the Korean Chemical Society
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• 제29권6호
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• pp.1125-1130
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• 2008

A series of dihydroxylated chalcone derivatives with diverse substitution patterns on a phenyl ring B and the para-substituents on a phenyl ring A were prepared, and their radical scavenging activities were evaluated by simple DPPH test to determine quantitative structure-activity relationship in these series of compounds. The chalcone compounds with the ortho- (i.e. 2',3'- and 3',4'-) and para- (i.e. 2,5'-) substitution patterns show an excellent antioxidant activities (80-90% of control at the concentration of 50 $\mu$M) which are comparable to those of ascorbic acid and $\alpha$ -tocopherol as positive reference materials. On the contrary, the compounds with meta- (i.e. 2',4'-, 3',5'-) substitution pattern demonstrate very dramatic decrease in activities which are around 25% of the control even at the concentration of 200 $\mu$ M (IC50 > 200 $\mu$ M). These dramatic differences could be interpreted in terms of the ease formation of fairly stable semiquinone radicals from the ortho- and parasubstituted chalcone molecules through facilitating electron delocalization. Our results indicate that the substitution patterns of two hydroxyl groups on ring B are very important structural factors for their radical scavenging activity enhancement. Meanwhile, the substituents at para-position of the phenyl ring A of chalcones have no influence on the activity.

• 한국육종학회지
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• 제40권1호
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• pp.80-83
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• 2008

경남농업기술원 화훼육종연구소에서 '98년부터 교배조합육성을 위하여 국내의 재배농가와 종묘업체로부터 품종을 수집한 후, '01년 3월에 핑크색 대륜계의 'Grandeur'를 모본, 백색 소륜계의 'Nova Zembla'를 부본으로 인공교배를 실시하여 교배조합으로부터 284개의 종자를 획득하였다. 교배 후 결실이 된 조합은 채종 즉시 파종하였으며, 파종 1개월 후 248개의 유묘를 획득하였으며, 발아된 유묘는 본엽이 4~5매 전개되었을 때 화훼육종연구소 유리온실내의 선발 포장에 정식하였다. 그 후 교잡 1세대를 육묘하여 화색이 선명하고 수량이 많은 우수 2개체(01128-65, 94)를 1차로 선발하였다. 그 후 특성이 우수한 01128-94(경남 G-22)개체를 생장점배양에 의해 개체증식 후 화훼육종연구소 유리온실내의 특성검정 포장에 정식하여 2003년 6월부터 2004년 10월까지 3회에 걸쳐 생육 및 수량특성 검정을 실시하였다. 특성검정을 실시한 결과 화색, 화형, 수확량 등 품질과 수량이 우수하다고 판단되어 2005년 농작물 직무육성 신품종선정위원회의 심의를 거쳐 'Summer Ring'로 명명하였다. 'Summer Ring'은 화색이 선명한 핑크색의 반겹꽃 절화용으로 수량이 많고 안정된 소륜화로서 화색과 화심색이 잘 조화된 기호도가 높은 품종이다. 본당 수량은 연간 3회 검정 결과 평균 68.9개이며, 평균절화수명은 14.7일이다.