• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.129-129
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• 2016

Graphene, as a single layer of $sp^2$-bonded carbon atoms packed into a 2D honeycomb crystal lattice, has attracted much attention due to its outstanding properties. In order to synthesize high quality graphene, transition metals, such as nickel and copper, have been widely employed as catalysts, which needs transfer to desired substrates for various applications. However, the transfer steps are not only complicated but also inevitably induce defects, impurities, wrinkles, and cracks of graphene. Furthermore, the direct synthesis of graphene on dielectric surfaces has still been a premature field for practical applications. Therefore, cost effective and concise methods for transfer-free graphene are essentially required for commercialization. Here, we report a facile transfer-free graphene synthesis method through nickel and carbon co-deposited layer. In order to fabricate 100 nm thick NiC layer on the top of $SiO_2/Si$ substrates, DC reactive magnetron sputtering was performed at a gas pressure of 2 mTorr with various Ar : $CH_4$ gas flow ratio and the 200 W DC input power was applied to a Ni target at room temperature. Then, the sample was annealed under 200 sccm Ar flow and pressure of 1 Torr at $1000^{\circ}C$ for 4 min employing a rapid thermal annealing (RTA) equipment. During the RTA process, the carbon atoms diffused through the NiC layer and deposited on both sides of the NiC layer to form graphene upon cooling. The remained NiC layer was removed by using a 0.5 M $FeCl_3$ aqueous solution, and graphene was then directly obtained on $SiO_2/Si$ without any transfer process. In order to confirm the quality of resulted graphene layer, Raman spectroscopy was implemented. Raman mapping revealed that the resulted graphene was at high quality with low degree of $sp^3$-type structural defects. Additionally, sheet resistance and transmittance of the produced graphene were analyzed by a four-point probe method and UV-vis spectroscopy, respectively. This facile non-transfer process would consequently facilitate the future graphene research and industrial applications.

• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.306-309
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• 2007

PXLM(Phosphor based x-ray light modulator) has a combined structure by phosphor, photoconductor, and liquid crystal and it can realize x-ray image of high resolution in clinical diagnosis area. In this study, we fabricated a photoconductor and investigated electrical and optical properties to confirm application possibility of radiator detector of PXLM structure. As photoconductor, amorphous selenium(a-Se), which is used most in DR(Digital radiography) of direct conversion method, was used and for formation of thin film, it was formed as $20{\mu}m-thick$ by using thermal vacuum evaporation system. For a produced a-Se film, through XRD(X-ray diffraction) and SEM(Scanning electron microscope), we investigated that amorphous structure was uniformly established and through optical measurement, for visible light of 40 $0\sim630nm$, it had absorption efficiency of 95 % and more. After fabricated a-Se film on the top of ITP substrate, hybrid structure was manufactured through forming $Gd_2O_3:Eu$ phosphor of $270{\mu}m-thick$ on the bottom of the substrate. As the result to confirm electrical property of the manufactured hybrid structure, in the case of appling $10V/{\mu}m$, leakage current of $2.5nA/cm^2$ and x-ray sensitivity of $7.31nC/cm^2/mR$ were investigated. Finally, we manufactured PXLM structure combined with hybrid structure and liquid crystal cell of TN(Twisted nematic) mode and then, investigated T-V(Transmission vs. voltage) curve of external light source for induced x-ray energy. PXLM structure showed a similar optical response with T-V curve that common TN mode liquid crystal cell showed according to electric field increase and in appling $50\sim100V$, it showed linear transmission efficiency of $12\sim18%$. This result suggested an application possibility of PXLM structure as radiation detector.

• 한국비블리아학회지
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• 제2권1호
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• pp.132-177
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• 1974

Toe public library may perform a social good only when its objectives are adequate to the community's needs. The present purpose of the public library in the Korean Library Act has no direct concern for our social needs from its very beginning because it was not created in response to our social needs but transplanted from American principles. It is, therefore. difficult to expect socially useful output of our public library programs under the present purpose which may be inadequate to our social tradition and needs. This study purposes to examine validity of the present purpose of the public library in the Korean Library Act, in the light of our community needs and our own library tradition. The methods employed to achieve the purpose of the study are (1) to survey needs of the library frequenters through questionnaire, and interviews with the public librarians in Seoul, (2) to gather the statistical data relevant to, and supporting, the hypothesis, and (3) to compare our social background with that of the United States of which the American purpose, a model for our present purpose, came out. The conclusion is as follows: A. The idea to induce people to pull themselves upward by providing for all the members of the community access to the world's best books shelved in the public library should be abandoned. The reasons are (1) that the idea is alien in our public library tradition, (2) that little demand of the community goes with the idea, and (3) that reading outside the library has come into wide practice, thanks to recent increase in individual income and that in publications. B. That the public library maintains fiction and other recreational reading materials is meaningless in the light of the community needs. These are the two explanations supporting the thesis. (1) The "uplift" theory has proved inoperative and people apparently do not progress from, light fiction to more respectable fare. (2) The conviction that fiction and other recreational reading materials keep the middling classes from the "vicious" entertainments maintaining order in the community by giving them a harmless source of recreation has lost its significance as the modern society provides a number of choices in recreation: television is an obvious example. C. The nature of the informational needs of the community has radically changed, so radically as to require substantial changes in the outlook, collections, and services of the public library, which is :slow in adopting itself to the new social surroundings in Korea. D. 92.2 per Cent of the present frequenters of the public library are high school and college students. Since the library is to meet the existing community needs it should turn its attention to the student group, and develop the means to serve it better, not the "theoretical group of specialists who do not come to "the public library. E. In revision of the purpose of the public library, priority of each objective should be given. The priorities in the last analysis are research and information. culture, recreation in that order.

• 한국토양비료학회지
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• 제43권5호
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• pp.716-721
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• 2010

농산물 탄소성적표지제도 도입을 위한 농업분야 LCI database에 대한 연구를 위하여 쌀의 생산체계를 대상으로 전과정평가를 수행하였다. LCI 구축을 위한 영농 투입물과 산출물에 대한 데이터결과 유기질비료와 복합비료가 각각 4.29E-01 kg $kg^{-1}$ rice, 2.30E-01 kg $kg^{-1}$ rice으로 영농단계에서 가장 높은 투입량을 보였고, 영농단계에서 발생하는 직접대기배출물이 3.23E-02 kg $kg^{-1}$ rice의 배출값을 나타내었다. 쌀생산체계에서 발생하는 온실가스를 중심으로 전과정 목록분석을 수행한 결과 탄소성적값은 8.70E-01 kg $CO_2$-eq. $kg^{-1}$ rice이었다. 이 중 $CO_2$가 7.02E-01 kg $CO_2$-eq. $kg^{-1}$ rice로 온실가스 발생의 약 80%가 $CO_2$였고, $CH_4$과 $N_2O$의 배출량은 각각 13%, 5%의 비중을 차지하였다. 전과정 영향평가 결과 지구온난화에 기여하는 주요인자는 유기질비료 생산 공정이 42%, 무기질비료 생산공정이 40%로 비료생산공정에 의한 비중이 가장 높았다.

• 대한치과교정학회지
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• 제14권2호
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• pp.187-202
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• 1984

There are evidences that exogenous electric currents are capable of enhancing bone formation and resolution, and that the conversion of the bioelectric response to biochemical activity provides the directional component of orthodontic tooth movement. In addition, evidence has implicated cyclic nucleotides in alveolar bone cellular activation mechanism during orthodontic tooth movement. In view of these evidences, this study was performed to investigate the effects of exogenous electric currents on cyclic nuclotide levels in feline alveolar bone and the possible clinical application of electric currents as an additional orthodontic tool. In the first study, three groups of three adult cats were subjected to application of a constant direct current of $10{\pm}2$ microamperes to gingival tissue near maxillary canine noninvasively for 1, 3, and 7 days respectively. In the second study, three groups of three adult cats each were treated by an electric-orthodontic procedure for 1, 3, and 7 days respectively. The left maxillary (control) canine received an orthodontic force of 80gm alone at time of initiation, while the right maxillary (experimental) canine received combined force-electric stimulation (80gm of force and $10{\pm}2$ microamperes of a constant D.C. currents). Alveola, bone samples were obtain from the mesial (tension and/or cathode) and the distal (compression and/or anode) sites surrounding maxillary canines as well as from contralateral control sites. The samples were extracted, boiled, homogenized, and the supernatants were assayed for cyclic nucleotides (cAMP, cGMP) by a radioimmunoassay method. And also the amount of tooth movement was measured in the second study. On the basis of this study, the following conclusions can be drawn: 1. The fluctuation pattern of cyclic nucleotide levels in alveolar bone treated by exogenous electric currents was similar to that treated by orthodontic force. 2. The cAMP levels in alveolar bone of electrically treated teeth significantly elevated above the control values. And of electrically treated teeth, the values of the anode sites were higher than those of the cathode sites. 9. The cGMP levels in alveolar bone of electrically treated teeth elevated above the control values at the initiation phase of treatment, but dropped below the control values at time of termination. And of electrically treated teeth, the values of the cathode sites were higher than those of the anode sites. 4. The rate of tooth movement in teeth . treated by force-electric combination increased with the length of treatment as compared to that treated by mechanical force alone.

• Asian-Australasian Journal of Animal Sciences
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• 제19권6호
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• pp.892-897
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• 2006

An experiment was designed to study the nutritional value of Chinese brown rice and maize for growing pigs. Six male grower pigs (Duroc${\times}$Landrace${\times}$Large White, $24.3{\pm}1.26$ kg average initial BW) were surgically fitted with a simple T-cannula at the terminal ileum and allotted within a $2{\times}2$ Latin square design. The pigs were fed either a maize or brown rice diet in a direct method to determine their digestibility. The brown rice used in this experiment was husked from one kind of early, long grain, and non-glutinous rice (ELGNR, indica rice: non-waxy rice, containing amylopectin and amylose) in southern China. Chromic oxide was used as a marker. The diets were supplied at about 4.0% of body weight in dry matter/d. Total faeces and urine were collected on days 4 and 5; digesta was collected on days 6-8 in each period. The average body weight was 24.3 kg at the start of the experiment and 27.6 kg at the end. The results showed that the apparent ileal digestibilities of most amino acids of brown rice were significantly higher than those in maize (p<0.01), as were the apparent ileal digestibilities of crude protein (CP), digestible energy (DE), organic matter (OM) and dry matter (DM) (p<0.05). However, the apparent ileal starch digestibilities of the two treatments were similar (p>0.05). The values of the apparent faecal digestibilities derived from the two methods, marker and total faecal-collection methods, were very similar and also correlated with each other. The difference in absolute value of the apparent faecal digestibilities between brown rice and maize was smaller compared to that of the apparent ileal digestibilities. The net protein utilization was higher (p = 0.07) and the DE metabolizable rate was significantly higher (p<0.01) for brown rice than for maize. The metabolizable energy (ME) of brown rice is similar to that of maize, while the DE of brown rice was relatively lower. It can be concluded that Chinese brown rice are better than maize not only in apparent ileal digestibilities, but also in metabolizable rate of amino acids and gross energy under the present study conditions.

• 동의생리병리학회지
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• 제23권3호
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• pp.715-722
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• 2009

The aim of this study was to investigate the safety of short-term use of Korean herbal medicine (KHM; prescribed herbal medicine by doctors of traditional Korean medicine) on liver function. Three hundred eighty four outpatients who took KHM for various conditions were enrolled for multi-center, prospective observational study. Of them 237 patients completed questionnaire and were checked liver function (aspartic aminotransferase;AST, alanine aminotransferase;ALT, alkaline phosphatase;ALP, total bilirubin;t-Bil, direct bilirubin;d-Bil, gamma glutamyltranspeptidase;GGT, protein and albumin) before and after taking KHM (duration; 21.4${\pm}$10.0 days), and data were analysed statistically. Of the 213 patients showing normal liver function test (LFT) at baseline, 209 (98.1%) remained within the normal range at the second test while 3 (1.4%) revealed slight increase of LFT. Only one subject had raised LFT regarding level of liver injury without perceived symptoms. Twenty-four of 237 patients were abnormal at baseline, and 16 at the second testing. Of the patients taking KHM, only 4 changed from normal to abnormal while 12 from abnormal to normal in their LFT. There were no significant increase in LFT level between the first and second test, except in the t-Bil level, however, the change of t-Bil was small and within normal range. The current study showed that the use of KHM did not increase the frequency of abnormal LFTs, at least in the short term.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.428-446
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• 1997

Restorative procedures can lead to weakening tooth due to reduction and alteration of tooth structure. It is essential to prevent fractures to conserve tooth. The resistance to fracture of the restored tooth may be influenced by many factors, among these are the cavity dimension and the physical properties of the restorative material. The placement of direct composite resin restorations has generally been found to have a strengthening effect on the prepared teeth. It is the purpose of this investigation to study the relationship between the cavity isthmus and the fracture resistance of a tooth in composite resin restorations. In this study, MO cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method and isthmus(1/4, 1/3, 1/2 of intercuspal distance) were varied. Two types of model(B and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall and R model was left unfilled. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as follows : 1. Displacement of buccal cusp in R model occurred and increased as widening of the cavity, and displacement in B model was little and not influenced by cavity width. 2. There was a significant decrease of stress resulting in increase of fracture resistance in B model when compared with R model. 3. With the increase of the isthmus width, B model showed no change in the stress and strain. In R model, the stress and strain increased both in the area of buccal-pulpal line angle and the buccal side of marginal ridge, therefore the possibility of crack increased. 4. The stress and strain were distributed evenly on the tooth in B model, but in R model, were concentrated on the buccal side of the distal marginal ridge and buccal-pulpal line angle, therefore the possibility of fracture increased.

• 생명과학회지
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• 제18권3호
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• pp.363-368
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• 2008

국내의 자생곤충 76종으로부터 다양한 용매를 이용하여 304종의 추출물을 조제한 후, 이들의 항혈전 활성을 평가하였다. 먼저 트롬빈 저해활성 평가 결과, 방아깨비, 왕잠자리, 비단노린재 및 끝검은메뚜기의 DMSO 추출물 4종, 알락수염노린재, 가시길쭉바구미, 잔날개여치, 털두꺼비하늘소, 송장벌레과 유충 및 등빨간거위벌레의 물 추출물 6종에서 우수한 활성을 확인하였다. 선정된 10종을 대상으로 aPTT 측정결과 비단노린재, 방아깨비 및 잔날개여치 추출물에서 미약한 증가가 나타났으나, 전반적으로 혈전 생성 저해의 유의적인 변화는 인정되지 않아, 이들 추출물들은 트롬빈을 직접 저해하는 것으로 추측되었다. 한편 항트롬빈 활성이 우수한 10종 추출물 중에서 방아깨비, 가시길쭉바구미, 알락수염노린재 및 송장벌레과 유충 추출물에서는 우수한 DPPH 소거능을 나타내어 이들의 약용 곤충자원으로의 개발 가능성을 확인하였다.

• 한국식품과학회지
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• 제28권6호
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• pp.1059-1064
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• 1996

키토산의 in vitro 돌연변이 억제활성을 Salmonella typhimurium reversion assay와 SOS chromotest 이용하여 살펴보았다. S. typhimurium에 의한 시험된 간접변이원 Trp-P-2에 대해서 0.1-1.0 mg/plate의 chitosan농도로 시험하였을 때, 24-65%의 돌연변이 억제활성을 나타내었다(p<0.01). Chitosan농도 0.1-0.5 mg/plate 범위에서는 용량-반응(dose-responese)관계를 나타내면서 저해효과를 나타내었으며, 0.5 mg/plate이상의 농도에서는 오히려 저해효과가 감소하는 경향이었다. 반면, 직접변이원인 SA 및 2-NF로 유도된 돌연변이에 대해서는 시험한 어느 농도에서는 chitosan에 의한 돌연변이 억제효과가 나타나지 않았다. Chitosan은 직접변이원인 4-NQO에 의한 SOS 유도에 대해 chitosan농도가 0.15 mg/assay 및 0.20 mg/assay일 때 4-NQO에 의해 유도된 유도지수(induction factor) 8.290을 4.226및 4.516으로 낮추어 46-49%의 저해활성을 나타내었다. 간접변이원인 Trp-P-2에 의한 SOS 유도에 대한 chitiosan의 억제효과는 시험한 chitosan의 농도범위에서 약 9-39%의 저해활성을 나타내었으며, chitosan농도가 0.1 mg/assay이 경우를 제외하고는 chitosan농도 증가에 따라 비례적으로 SOS유도 저해활성이 나타났다. Trp-P-2d 의해 DNA 손상을 유도한 다음 chitosan의 세포내 역제(bio-antimutagenicity) 활성을 살펴 본 결과, 저농도에서는 세포의 억제(desmutagenicity) 특성을, 0.75-1.0 mg/plate의 비교적 고농도에서는 세포내 억제특성을 나타내었다.