• 대한치과보철학회지
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• 제47권2호
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• pp.119-124
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• 2009

연구목적: 치과 영역에서 환자들의 심미적인 요구가 증가하면서 자연 치아의 색조를 재현할 수 있는 수복물의 개발이 이루어졌으며, 이러한 연구의 일환으로 도재와 복합레진의 특성을 겸비한 Ceromer(Ceramic Optimized Polymer)가 개발되었다. Ceromer는 기존의 복합레진에 무기질을 고밀도로 충전하여 물리적 성질을 향상시켰다. 연구 재료 및 방법:본 실험에서는 두 종류의 Ceromer[$Targis^{(R)}$(Ivoclar-vivadent AG., Schaan, Liechtenstein), $BelleGlass^{(R)}$(Kerr Co., Orange, CA, USA)]를 이용해 레진 전장관 형태의 시편을 제작하고 증류수에 침전한 후 발생하는 체적과 중량의 변화를 관찰하였다. 결과 및 결론:두 종류의 Ceromer 모두 수중 침적 시간이 증가할수록 높이와 폭이 증가되었으며, $Targis^{(R)}$보다 $BelleGlass^{(R)}$에서 더 큰 누적변화율을 보였다. 72시간까지 급격한 증가를 보이다 이후 누적변화율의 증가는 감소하였다. 통계적 분석결과 $Targis^{(R)}$의 높이와 무게의 누적 변화량이 24시간군과 나머지군 사이에 유의한 차이를 보였으며, $BelleGlass^{(R)}$에서는 폭과 무게에서 누적 변화량이 24시간군과 나머지군 사이에 유의한 차이를 보였다(<.05). $Targis^{(R)}$와 $BelleGlass^{(R)}$ 두 군간의 비교에서는 높이, 폭, 무게의 변화량은 통계적으로 유의한 차이를 보이지 않았으나 변화양상은 다르게 관찰되었다.

• 한국환경과학회지
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• 제25권3호
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• pp.337-343
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• 2016

The present study aimed to determine the influence of various root restriction media on seedling quality and early growth of strawberry after transplanting. The root activity of the seedlings, measured 20 days after fixation, was considerably higher (0.096, 0.090, and $0.063mg{\cdot}g^{-1}{\cdot}h^{-1}$ at 420, 450, and 480 nm, respectively) in expanded rice hull (ERH) treatment than in the sandy loam and loamy sand treatments. The volumetric water content (VWC) of the root media tested across 3 irrigation regimes (15 d, 30 d, 45 d) in the nursery field was highest in sandy loam (65.0-66.8%), followed by 59.4-61.3% in loamy sand and 38.6-45.3% in ERH. When growth parameters of runner plantlets were compared, ERH treatment was found to result in the highest crown thickness and fresh weights of root and above-ground parts. This had a favorable influence on above-ground tissue growth after transplanting to plastic house soil. As mentioned above, ERH treatment resulted in the highest seedling quality and early growth after transplanting. The results of this study would serve as useful on-site data for the production of high-quality strawberry seedlings.

• 한국환경과학회지
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• 제5권2호
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• pp.211-220
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• 1996

두 개의 황과 셀렌의 주개원자를 포함한 새로운 thia 및 diselena 크라운에데르 화합물을 합성하였다. 그리고 이 화합들을 중성운반체로 하고 PVC-가소제 (STPB)를 포함한 Hg(ll) 선택성 전극을 제작하였다. 이 전극들을 이용하여 여러 이온들의 전기화학적 선택성, 중성운반체의 종류 및 농도와 선택막의 매질에 대한 효과 그리고 실험용액의 pH변화에 대한 전극의 선택적 감응성들의 영향을 각각 검토하였다. 1,10-diselena-18-crown-6-PVC-STPB의 중성운반체의 막전극은 $10^{-2}$-10- M $Hg^{2+}$ 이온의 농도범위에서 ${28.2}\pm{0.6}$의 Nernstian 기울기를 갖는 좋은 선형적 감응성을 갖는다. 그리고 이 전극은 pH 2.5~6.0 범 위에서 알칼리토 금속, 몇가지 중금속 및 희토류 금속 이온에 대하여 좋은 선택성을 갖는다. 특히 이 전극은 수용액 중에서.$1^-$ 이온으로 Hg^{2-}$ 이온을 전위차 적정할 수 있는 센서로서 응용할 수 있다.

• 대한치과기공학회지
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• 제34권4호
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• pp.337-344
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• 2012

Purpose: This study examined the corrosion level by alloy type and pH, and used the corrosion levels as the dental health data. The study utilized one Ni-Cr alloy for the full and removable partial denture metal frameworks and two Ni-Cr alloys for porcelain-fused-to-metal crown, among the non-beryllium dental casting non-precious Ni-Cr alloys. Methods: The alloy specimens were manufactured in $10cm^2$ and stored in the corrosive solution(pH 2.2-4.4) in the electrical water bath($37^{\circ}C$) for seven days. Afterwards, the metal ions were quantitatively analyzed using the ICP. Results: Of the three metal alloys, Bellabond-Plus$^{(R)}$alloy and SOLIBOND N$^{(R)}$alloy, with 22% or higher chrome chemical contents, had higher corrosion resistance than Jdium-100$^{(R)}$alloy with 20% chrome chemical content. In all three alloys, the corrosion of Ni was highest, and metal ion corrosion was higher in the pH 2.2 corrosive solution. Conclusion: Although Ni-Cr alloy was not very corrosive, a Ni-allergic patient should not have Ni-Cr alloy prosthesis. The Ni-Cr alloy for porcelain-fused-to-metal crown should be designed for the dental porcelain to cover the whole crown.

• 한국해안·해양공학회논문집
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• 제34권2호
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• pp.27-36
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• 2022

파랑이 구조물과 만나게 되면 강한 처오름이 발생하게 되며, 이러한 처오름은 월파를 야기하게 된다. 월파에 의해 야기된 월파수괴에 의해 구조물 배후면에 강한 낙하파압이 작용하게 된다. 구조물 배후면의 포장체 등을 설계하기 위해서는 월파 등에 의한 낙하파압이 산정되어야 하지만 여전히 불명확한 부분이 있다. 본 연구에서는 경사식구조물을 대상으로 월파에 의한 낙하파압 계측을 위한 수리실험을 수행하였으며, 수리실험에서는 파랑조건, 여유고, 피복재 높이 및 파라펫의 유무에 따른 낙하파압의 변화를 계측하였다. 상치콘크리트에는 월파의 효과적인 저감을 위해 파라펫이 설치되기도 하지만, 파라펫 설치로 인해 배후면에 작용하는 낙하파압은 증가하는 것으로 검토되었다. 수행된 실험결과를 이용하여 경사식구조물의 상치콘트리트 배후면에 작용하는 최대 낙하파압을 산정할 수 있는 경험식을 제안하였다.

• 분석과학
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• 제6권4호
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• pp.411-415
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• 1993

지방산을 UV 검출기를 사용하여 HPLC로 분석하기 위하여 2-bromoacetyltriphenylene을 유도체화제로 응용하였다. 18-crown-6-ether를 촉매로 한 유도체화반응은 매우 신속, 간편하고 정량적으로 진행되었으며, HPLC상에서 지방산의 검출한계가 1ng 수준으로 그 감도가 양호하였다. 또한 $C_{12}$부터 $C_{22}$까지 9종류의 포화지방산이 역상컬럼상에서 acetonitrile-물 gradient 조건으로 동시에 분리가 가능하였다. 이를 응용하면 각종 생체 시료로부터 미량의 지방산들에 대한 동시분석이 가능하리라 기대된다.

• 한국항만학회지
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• 제8권1호
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• pp.23-30
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• 1994

This study discusses the wave transformation(wave reflection and transmission) by a impermeable submerged breakwater with one ray, and integrated horizontal wave pressure acting on the structure. Numerical method in this study is based on the simplified eigenfunction expansion method and linear wave theory. Although this method is very simple, the results give good agreement with the one of the strict eigenfunciton expansion method, especially, in case that the crown width of the submerged breakwater becomes longer and its crown water depth shallower. Therefore, it is concluded that this simplified method is one good method in planning coastal structures as like the submerged breakwater in this study, and computing their wave transformations.

• 대한치과보철학회지
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• 제39권6호
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• pp.599-610
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• 2001

Due to an increasing interest in esthetics and concerns about toxic and allergic reactions to certain alloys, patients and dentists have been looking for metal-free tooth-colored restorations. Recent improvement in technology of new all-ceramic materials and composite materials has broadened the options for esthetic single crown restorations. The aim of this investigation was to study the fracture strength of the metal-free posterior single crowns fabricated using two recently introduced systems, Empress 2 ceramic and Targis-Vectris. Forty premolar-shaped stainless steel dies with the 1mm-wide circumferential shoulder were prepared. Ten cylindrical crowns having a diameter of 8.0mm and total height of 7.5mm were fabricated for each crown system respectively(PFM, Empress staining technique, Empress 2 layering technique, and Targis- Vectris). The crowns were filled with cement and placed on the stainless steel dies with firm finger pressure. The crowns were then stored in distilled water at room temperature for 24 hours before testing. The crowns were tested for fracture strength in an Instron universal testing machine (Instron 6022). With a crosshead speed of 1mm/min the center of the occlusal surface of the crown was loaded using a 4-mm-diameter stainless steel ball until fracture occurred. The fracture surfaces of the crowns were gold coated and examined using scanning electron microscopy(Jeol JSM-840 Joel Ltd., Akishima, Tokyo, Japan). Within the parameters of this study the following conclusions were drawn: 1. The mean fracture strength for PFM crowns was 5829(${\pm}906$)N; for Empress staining technique the fracture strength was 1697(${\pm}604$)N; for Empress 2 Layering technique the fracture strength was 1781N(${\pm}400$)N, and the fracture strength for Targis- Vectris was 3093(${\pm}475$)N. 2. The fracture strength of the PFM crowns was significantly higher than that of the Empress 2 and the Targis-Vectris crowns (P<0.05). 3. The fracture strength of the Targis-Vectris crowns was significantly higher than that of the Empress 2 crowns (P<0.05). 4. No statistical difference was found when Empress staining technique was compared with Empress 2 layering technique. 5. The SEM image of fracture surface of Empress 2 crown showed a very dense microstructure of the lithium disilicate crystals and the SEM image of fracture surface of Targis-Vectris crown showed indentations of Vectris and some fibers tom off from Vectris.

• 한국환경복원기술학회지
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• 제11권3호
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• pp.20-27
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• 2008

This study was conducted to investigate the influence of thinning and pruning on characteristics of forest stand, mesopore ratio and soil water content at the Pinus koraiensis stands in Gwangneung, Gyeonggido. The Pinus koraiensis had been planted in 1976 and thinning and pruning were carried out in 1996. A sample area survey was conducted at experimental plots (thinned and unthinned) in 1998 and 2005, and mesopore ratio and soil water content have been monitored from 2000 to present. Average tree height of the thinned plot increased from 10.9m to 13.2m and from 10.3m to 12.8m for the unthinned plot. Average D.B.H of the thinned plot increased from 15.9cm to 21.1cm and from 14.5cm to 16.7cm for the unthinned plot during the period 1998-2005. Crown density at the thinned plot increased from 81.5% to 95.0% and from 89.5% to 95.0% for the unthinned plot during the period 1998-2005. Mesopore ratio (pF2.7) of A layer soil at the thinned plot was 40.1% while that of the unthinned plot was 37.3%. Changes of mesopore ratio at unthinned plot were not associated with stand age, but those at thinned plot had increased and then decreased, showing declining of the practice effect. Average soil water content at the thinned plot were 23.7% and 22.4% for the unthinned plot. Soil watercontents at both plots have been increased with increase in stand age. But the difference of soil watercontent at each plot has been decreased, especially at the depth of 10cm.

• 한국식품조리과학회지
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• 제21권5호
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• pp.557-566
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• 2005

The purpose of this study was to estimate the microbial quality of some raw vegetables and to suggest a safer method of sanitization and pre-preparation in foodservice operations. The production of Dotori-muk muchim was monitored from ingredient preparation to final product and during holding at different temperatures. Three sanitization methods were performed during the preparation with crown daisy (tap water, chlorine water, electrolyzed water). The largest reduction of microbial counts was for electrolyzed water (after treatment, total plate counts were decreased to $2.76{\sim}3.76$ Log CFU/g, coliform counts were not detected). In the case before immersed in chlorine water, Performed first washing is larger the effective reduction of microbial counts than or not.