• Title/Summary/Keyword: 물리적 성질

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Photocatalytic Decomposition of Rhodamine B over BiVO4 Doped with Samarium Ion (Sm 이온이 도핑된 BiVO4에서 로다민 B의 광촉매 분해 반응)

  • Hong, Seong-Soo
    • Clean Technology
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    • v.27 no.2
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    • pp.146-151
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    • 2021
  • Pure and Sm ion doped BiVO4 catalysts were synthesized using a conventional hydrothermal method and characterized by XRD, DRS, SEM, and PL. We also examined the activity of these materials on the photocatalytic decomposition of rhodamine B under visible light irradiation. The doping of Sm ion into BiVO4 catalyst changed the ms-BiVO4 crystal structure into the tz-BiVO4 crystal structure in the low synthesis temperature. Light absorption analysis using DRS showed that all the catalysts displayed strong absorption in the visible range of the electromagnetic spectrum regardless of Sm ion doping. In addition, an amorphous morphology was shown in the pure BiVO4 catalyst, but the morphology of the BiVO4 catalyst doped with Sm ion was changed into an ellipse shape and also the particle size decreased. In the photocatalytic decomposition of rhodamine B, Sm ion doped BiVO4 catalyst showed higher photocatalytic activity than the pure BiVO4 catalyst. In addition, the Sm3-BVO catalyst doped with 3% Sm ion showed the highest photocatalytic activity, as well as the highest formation rate of OH radicals (•OH) and the highest PL peak. This result suggests that the formation rate of OH radicals produced in the interface between the photocatalyst and water is well correlated with the photocatalytic activity.

A Study on the Evaluation for Performance of Body Armor Vest using ANOVA (분산분석을 이용한 방탄조끼의 방탄성능 평가에 관한 연구)

  • Park, Jae Woo;Byun, Kisik;Cho, Sung-Yong;Kim, Suk Ki;Yeo, Yongheon;Kwon, Jae Wook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.1
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    • pp.372-378
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    • 2021
  • A body armor vest is a form of munition related directly to the safety and life of combatants. Therefore, it must meet the requirements for ballistic resistance. The ROK demands the performance of body armor vest meet the Level IIIA specified by the NIJ STD-0101.06 published by the US National Institute of Justice. This study performed acceptance tests on body armor vests. The factors for evaluating the ballistic resistance evaluated were not only whether it penetrates when shooting but also whether the BFS (Backface Signature) depth does not exceed 44 mm when it does not penetrate. The factors were assessed to determine if they were consistent or not. The BFS depth is affected by various test factors, such as the physical properties of the backing material and the changes in the amount of impact with the bullet velocity. In this study, an analysis of the bulletproof performance was performed by extracting the data with the same conditions using ANOVA to remove the influence of these external factors. The analysis revealed a correlation between the BFS depth, bullet velocity, vest conditions, and protection area. The mass production process was analyzed by estimating the Interval of BFS on each lot. Through this, a new methodology for ballistic resistance evaluation and paradigm for future quality assurance is suggested.

Performance of Pentacene-based Thin-film Transistors Fabricated at Different Deposition Rates (증착 속도에 따른 펜타센 박막 트랜지스터의 성능 연구)

  • Hwang, Jinho;Kim, Duri;Kim, Meenwoo;Lee, Hanju;Babajanyan, Arsen;Odabashyan, Levon;Baghdasaryan, Zhirayr;Lee, Kiejin;Cha, Deokjoon
    • New Physics: Sae Mulli
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    • v.68 no.11
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    • pp.1192-1195
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    • 2018
  • We studied the electrical properties of organic thin-film transistors (OTFTs) fabricated at different deposition rates by measuring the field-effect mobility and the threshold voltages. As the active layer, pentacene thin film with a thickness of 50 nm was deposited at a rate of $0.05{\AA}/s$ to $1.14{\AA}/s$. The thickness of the drain-source gold electrode was 50 nm. The mobility was $1.9{\times}10^{-1}cm^2/V{\cdot}s$ at a deposition rate of $0.05{\AA}/s$, the mobility increased to $5.2{\times}10^{-1}cm^2/V{\cdot}s$ when the deposition rate was increased to $0.4{\AA}/s$, and then the mobility decreased to $6.5{\times}10^{-1}cm^2/V{\cdot}s$ when the deposition rate decreased to $1.14{\AA}/s$. Thus, the mobility of pentacene OTFTs was observed to depend on the thermal deposition rate.

Biaxial Strain Analysis of Various Fixation Models in Porcine Aortic and Pulmonary Valves (돼지 대동맥 판막과 폐동맥 판막의 고정 방법에 따른 양방향 압력-신장도의 비교분석)

  • Cho, Sung-Kyu;Kim, Yong-Jin;Kim, Soo-Hwan;Choi, Seung-Hwa
    • Journal of Chest Surgery
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    • v.42 no.5
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    • pp.566-575
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    • 2009
  • Background: The function of a bioprosthetic heart valve is determined largely by the material properties of the valve cusps. The uniaxial tensile test has been studied extensively. This type of testing, however, does not replicate the natural biaxial loading condition. The objective of the present study was to investigate the regional variability of the biaxial strain versus pressure relationship based on the types of fixation liquid models. Material and Method: Porcine aortic valves and pulmonary valves were assigned to three groups: the untreated fresh group, the fixed with glutaraldehyde (GA) group, and the glutaraldehyde with solvent (e.g., ethanol) group. For each group we measured the radial and circumferential stretch characteristics of the valve as a function of pressure change. Result: Radial direction elasticity of porcine aortic and pulmonary valves were better than circumferential direction elasticity in fresh, GA fixed and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of pulmonary valves were better than aortic valves in GA fixed, and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of aortic valves were decreased after GA and GA+solvent fixation(p=0.00), except for circumferential elasticity of GA+solvent fixed valves (p=0.785). The radial (p=0.137) and circumferential (p=0.785) direction of elasticity of aortic valves were not significantly different between GA fixed. and GA+solvent fixed groups. Radial (p=0.910) and circumferential (p=0.718) direction of elasticity of pulmonary valve also showed no significant difference between GA fixed and GA+solvent fixed groups. Conclusion: When fixing porcine valves with GA, adding a solvent does not cause a loss of mechanical properties, but, does not improve elasticity either. Radial direction elasticity of porcine aortic and pulmonary valves was better than circumferential direction elasticity.

A Study on Physical Properties About Velvet Antler of the Elk(Cerus canadensis) (엘크 녹용의 물성 특성에 관한 연구)

  • Sung, S.H.;Han, J.H.;Kim, Y.M.;Kim, B.K.
    • Journal of Animal Environmental Science
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    • v.13 no.3
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    • pp.201-210
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    • 2007
  • In this study, physical properties of Elk antler was investigated to develop the optimum drying and packaging methods for improving the antler quality as well as deal with diversify of demand. After the antler was sliced with 5 mm thickness, and the compressive, shear, and tensile stresses were measured at the center and velvet parts of pre-dried and dried antlers after the contained water rate of the dried antlers was maintained below 10%. The results are as follows. 1. Considering the center of pre-dried antlers, the compressive stresses were $60.73\;g/mm^2$, $145.65\;g/mm^2$, and $260.97\;g/mm^2$, respectively at the upper, middle, and lower parts while $70.67\;g/mm^2$, $811.90\;g/mm^2$, $3,235.52\;g/mm^2$, respectively for velvet layer. Considering the center of dried antlers, the compressive stresses were $190.43\;g/mm^2$, $445.81\;g/mm^2$, and $705.86\;g/mm^2$, respectively at the upper, middle, and lower parts while $734.01\;g/mm^2$, $1,238.40\;g/mm^2$, $4,134.03\;g/mm^2$, respectively for velvet layer. 2. For the pre-dried, the shear stresses were $50.24\;g/mm^2$, $294.44\;g/mm^2$, and $423.47\;g/mm^2$, respectively, and $124.14\;g/mm^2$, $367.69\;g/mm^2$, and $425.86\;g/mm^2$, respectively for the dried antlers. 3. The tensile stresses were $13.59\;g/mm^2$, $62.85\;g/mm^2$, and $112.07\;g/mm^2$, respectively for the pre-dried and $77.24\;g/mm^2$, $175.87\;g/mm^2$, and $184.06\;g/mm^2$, respectively for the dried antlers. 4. In the case of drying antlers, the physical characteristics of the antlers was. changed such as moisture evaporation, contraction, and surface hardening. For the center part, the changes of the physical characteristics were more significant at the lower part while at the upper part for the velvet layer. 5. The stress changes of Elk antlers was shown very remarkably according to growth point. Moreover, the stress was clearly higher at velvet layer part to the center part, base parts compared to the upper parts.

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Representative Physical and Chemical Properties of Korean Soils by the Results from Detailed Soil Survey (우리나라 토양(土壤)의 대표적(代表的)인 물리화학적(物理化學的) 특성(特性) (정밀토양조사결과(精密土壤調査結果)를 중심(中心)으로))

  • Hur, Bong-Koo;Jo, In-Sang;Min, Kyeong-Beom;Um, Ki-Tae
    • Korean Journal of Soil Science and Fertilizer
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    • v.17 no.4
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    • pp.330-336
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    • 1984
  • These studies were aimed to find out the representative values of physico-chemical properties in Korean soils and to serve the basic informations to improve the soil properties for increasing the soil productivity. By the results of detailed soil survey, 14 physico-chemical properties (soil texture, moisture characteristics, organic matter content etc) were collected from 315 series of soils except Cheju soils, computerized the simple mean and the distributed area by weighted mean values with grouping of land use, drainage class and soil type. The results were as follows; 1. Simple mean values within the efficient soil depth in whole country soils were clay 20.0%, organic matter 2.03% and CEC 10.3me/100g. But weighted mean values with land area belonged to the same soil series were clay 18.0%, OM 1.85% and CEC 8.6me/100g. 2. Mean values of paddy soils weighted by area were clay 19.7%, OM 2.0% and CEC 9.1me/100g but those of upland soils were 17.9%, 1.8% and 8.1me/100g and forest soils were 16.7%, 1.8% and 8.6me/100g respectively. 3. Weighted mean values of moderately well soils with covered area were clay 18.9%, organic matter 1.7%, CEC 8.4me/100g but those of imperfectly drained soils were 21.3%, 2.2% and 9.5me/100g, and those of poorly drained soils were 15.1%, 1.8% and 9.9me/100g respectivcly. 4. Simple mean and area weighted mean values of clay content, pH, organic matter contents, cation exchange capacity and base saturation were calculated by the types of paddy and upland.

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Studies on the Properties of Populus Grown in Korea (포플러재(材)의 재질(材質)에 관(關)한 시험(試驗))

  • Jo, Jae-Myeong;Kang, Sun-Goo;Lee, Yong-Dae;Jung, Hee-Suk;Ahn, Jung-Mo;Shim, Chong-Supp
    • Journal of the Korean Wood Science and Technology
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    • v.10 no.3
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    • pp.68-87
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    • 1982
  • In Korea, this is the situation at moment that the total demand of timber in 1972 is more than 5 million cubic meters. On the other hand, however, the available domestic supply of timber at the same year is only about, 1 million cubic meters. A great unbalancing between demand and supply of timber has been prevailing. To solve this hard problem, it has been necessitiated to build up the forest stocks as early as possible with fast grown species such as poplar. Under circumstances, poplar plantations which have been carryed on government and private have reached to large area of 116,603 hectors from 1962 up to date. It has now be come a principal timber resources in this country, and required the basic study on various properties of wood for it's proper utilization, since it has not been made of any systematic study on the properties of Populus grown in Korea. In order to investigate the properties such as anatomical, physical and mechanical properties of nine different species (P. euramericana Guiner I-214. P. euramericana Guiner I-476, P. deltoides Marsh, P. nigra var. italica (Muchk) Koeme, P. alba L.,P. alba $\times$ glandulosa P. maximowiczii Henry, P. koreana Rehder, P. davidiana Dode) of poplar for their proper use and development of new ways of grading processing and quality improving, this study has been made by the Forest Research Institute.

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자성유체 윤활제의 개발 동향

  • 김영규;심우전;김청균
    • Tribology and Lubricants
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    • v.12 no.1
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    • pp.1-5
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    • 1996
  • 자성유체는 자연에서 추출한 것이 아니라 자화성(Magnetizability)과 유도성(Flowability)을 동시에 갖도록 합성한 특수액체이다. 자성유체는 1960년대 중반에 미국의 NASA에서 처음 개발된 이후로 윤활, 밀봉, 감쇄, 의료 등의 분야에서 응용연구가 많이 진행되었기 때문에 고도의 정밀도를 요하는 항공, 우주산업, 컴퓨터와 반도체 분야 등에서 실용화가 크게 진전되고 있다. 특수물질일 자성유체는 전기적으로 도체인 10nm 정도의 미세한 자기입자(Magnetic particles)에 코팅을 한 후, 이것을 물, 탄화수소, 플루오르카본, 에스터 등의 매개유체(Carrier Fluids)에 혼합시켜서 콜로이드 상태로 사용하게 된다. 자성유체는 미세한 자기입자들이 매개유체내에서 서로 충돌하면서 반발력을 발생시켜서 상호간에 늘 콜로이드 상태를 유지하고 있으며, 이 특수유체가 자기장의 영향을 받게 되면 점도가 증가하면서 특이한 성질을 갖게 된다. 상대 접촉 운동면에 경계마찰이나 혼합마찰을 하게 되면 윤활상태는 비교적 나쁘다. 이러한 마찰지역에 콜로이드상의 자성유체 윤활제를 공급하면 기존의 윤활제에 비하여 대단히 효과적으로 윤활을 할 수 있게 된다. 그러나 자성유체 윤활제가 마찰부위에 원활하게 공급하기 위해서는 미끄럼 마찰부에서 자기장을 잘 형성시킬 수 있는 도체이어야 하기 때문에 특별한 윤활 시스템 설계가 제시되어야 한다. 자성유체 윤활제는 합성으로 제조된 특수물질로 여러가지 장점을 갖고는 있으나 기존 윤활유와의 적합성, 마찰열, 밀봉압력 등의 조건에서 제한적으로 사용될 수 밖에 없으므로 항공, 우주 산업이나 석유 화학분야와 같이 특수 환경에서만 사용되고, 또한 기존의 광유계 윤활제에 비하여 대단히 고가하는 문제점을 갖고 있다. 그러나 윤활 마찰면의 다양화와 가혹한 사용조건은 자성유체 윤활제의 연구개발 필요성을 크게 증대시키고 있다.xed Effects Model)을 결정하고, 각각에 해당하는 통계모형을 구축하였다. 이 결과 (1) 업종 및 기업규모별로 그룹간에 유의한 특성이 발견되었으며, (2) R&D 및 광고투자는 기업의 시장성과를 설명하는 중요한 변수이나, (3) R&D 투자의 경우는 광고에 비해 불확실성이 존재하는 것으로 나타났고, (4) 수리모형에서 도출된 한계원리가 통계모형에서도 유효한 것으로 드러났다.등을 토대로 한 10대 산업을 육성하기 위하여 과학기술부는 기술수요조사를 바탕으로 49개 주요기술을 도출하여, 과학기술 일류 국가 실현, 국민소득 2만불 달성이라는 국가적 슬로건을 내걸고 “차세대 성장동력” 창출을 위한 범정부차원의 기획과 연구비의 집중투자를 추진하고 있다.달성하기 위해서는 종합류류 전산망의 시급한 구축과 함께 화물차의 적재율을 높이고 공차율을 낮출 수 있는 운송체계의 수립이 필요한 것으로 판단된다. 그라나 이러한 화물전용차선의 효과는 단기적인 치유책일 수밖에 없기 때문에 물류유통 시설의 확충을 위한 사회간접자본의 구축을 서둘러 시행하여야 할 것이다.으로 처리한 Machine oil, Phenthoate EC 및 Trichlorfon WP는 비교적 약효가 낮았다.>$^{\circ}$E/$\leq$30$^{\circ}$NW 단열군이 연구지역 내에서 지하수 유동성이 가장 높은 단열군으로 추정된다. 이러한 사실은 3개 시추공을 대상으로 실시한 시추공 내 물리검층과 정압주입시험에서도 확인된다.. It was resulted from increase of weight of single cocoon. "Manta"2.5ppm produced 22.2kg of cocoon. It is equal to 9% increase in index, as compared to that of control. In case

On the Wood Properties of Genus Pinus Grown in Korea (소나무속(屬)의 재질(材質)에 관(關)한 시험(試驗))

  • Jo, Jae-Myeong;Kang, Sun-Goo;Ahn, Jung-Mo;Lee, Chan-Ho;Jo, Nam-Suk;Shim, Chong-Supp;Jung, Hee-Suk
    • Journal of the Korean Wood Science and Technology
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    • v.10 no.3
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    • pp.96-108
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    • 1982
  • Pinus is one of the most important species supplying domestic industrial timbers such as constitutional lumber, pulpwood, and mine props. It occupies nearly 50 percent of the total forest resources in Korea. With above conception, to develop this forest resources and to obtain the basic data on the reasonable and effective utilization of Pinus, this study was carried out. Five species (P. koraiensis S. et Z., P. densiflora S. et Z., P. thunbergii Parlat, P. densiflara far erecta, P. rigida Miller) grown in Kwangnoong experimental forest stand, Chungcheongnam-Do, and Gangwon-Do regions were selected as sample trees. Anatomical, physical, mechanical and chemical properties of them were investigated.

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THE FISSURE PENETRATION AND MICROLEAKAGE OF PIT AND FISSURE SEALANT WITH MECHANICAL PREPARATION (기계적 삭제방법을 이용한 치면열구전색제의 열구 침투도 및 미세누출)

  • Kim, Ji-Yeon;Lee, Jae-Ho;Park, Ki-Tae;Kim, Seong-Oh;Choi, Byung-Jai;Son, Heung-Kyu
    • Journal of the korean academy of Pediatric Dentistry
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    • v.32 no.1
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    • pp.164-173
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    • 2005
  • Mechanical preparation has been introduced to provide the sealant retention. The objective of this study was to compare the fissure penetration and the microleakage of pit and fissure sealant using mechanical preparation(mechanical preparation + acid etching) and acid etching only. An additional objective of this study was to compare the fissure penetration and the microleakage of unfilled and filled sealant in both methods. Sixty human premolars extracted for orthodontic purpose were selected. Thirty teeth were acid etched alone and remaining thirty teeth were prepared with a $\frac{1}{4}$ round bur and then acid etched. One-half of teeth in each surface treatment method were sealed with unfilled sealant and the other half were sealed with filled sealant. All of the teeth were thermocycled for 1200 cycles at $5^{\circ}C\;and\;55^{\circ}C$ and immersed in 5% methylene blue for 24 hours. Each tooth was sectioned bucco-lingually at mesial pit and distal pit and examined under a Measurescope. In the case of mechanical preparation, fissure penetration of sealant was significantly increased compared with the case of acid etching only(P < 0.05). The filled and unfilled sealant using mechanical preparation showed significantly decreased microleakage when compared with the unfilled sealant using acid etching only(P < 0.05). No differences were found in fissure penetration and microleakage between unfilled and filled sealant in both methods. Taken together, the results of this study suggest that mechanical preparation and filled sealant are recommended when placing pit and fissure sealant. However, further clinical studies should be performed in regard to microleakage.

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