• 대한치과기공학회지
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• 제42권3호
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• pp.234-239
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• 2020

Purpose: We investigated the marginal fit between abutment and metal copings according to impression technique, wax block types, and metal types. Methods: We selected the traditional impression method of using rubber impression materials and the digital impression method of using oral scanners, three types of wax blocks, and two types of metal, both of which were domestically and commercially available, were selected to produce metal copings, and the marginal fit was determined through the use of silicon replication. Results: The measurements of axial wall fit revealed that the IYV specimens had the best fit, with a mean gap of 24.11±5.95 ㎛, followed by CEV, CHV, CSS, CSV, CES, CHS, and IYS specimens (mean: 33.44±8.41 ㎛). The differences were not statistically significant. The marginal gap measurements showed that the CEV specimen had the smallest gap, 17.25±4.13 ㎛, followed by the CSV, CHV, CSS, CES, CHS, IYV, and IYS specimen (mean: 43.47±15.63 ㎛). The differences were statistically significant. Conclusion: The axial wall fit of the metal coping (VeraBond2V; Aalba Dent, Inc., Fairfield, CA, USA) produced by the lost wax technique with the traditional impression method was excellent. The marginal fit of the metal coping (VeraBond 2V) produced by wax milling with the use of an oral scanner was also excellent. The marginal fit of the metal coping was within the clinically acceptable limits in all groups.

• 대한치과보철학회지
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• 제38권4호
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• pp.472-483
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• 2000

Before impression making in the fixed restorations or other prosthesis, hemostatic solutions are used for hemostasis and moisture control. Hemostatic solutions effectively control bleeding but their major ingredients, acid removes smear layers which are formed in the tooth preparation, exposes the dentinal tubular orifices which are occluded by smear layers, makes dentinal tubular fluid displace more easily to the various external stimulus, and according to the hydrodynamic theory, consequently causes dentin hypersensitivity. To know the effect of hemostatic solutions on dentin permeability, coronal dentin discs, 1mm in thickness, were prepared from extracted third molars free from decay and wear, and a split chamber device was used. Hydraulic conductance values and SEMs, which were measured before and after treatment with $Astringedentr^{(R)},\;Altract^(R)\;and\;Epri-dent^{(R)}$, were compared and ana-lysed. The following conclusions were drawn: 1. Hydraulic conductance values which were measured after the treatment of hemostatic solutions were increased in all groups(p<0.05). 2. %change values of hydraulic conductance were compared but no significant difference was found among the three hemostatic solutions(p<0.05). 3. On SEM observations of all groups, after treatment smear layers were removed and dentinal tubular orifices were partially exposed. On the basis of these conclusions, the reckless use of hemostatic solutions should be restricted, and when in use, various methods should be considered to protect dentin.

• 한국초지조사료학회지
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• 제17권3호
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• pp.293-304
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• 1997

A field experiment was conducted at the forage experimental plots, Seoul National University, Suweon h m 1995 to 1996 to determine the effect of legume residues as a N source and N fertilizer on corn (Zea mays L.) silage yield, N uptake, and availability of inorganic N in the soil. Corn was grown following (i) red clover (Trifolium pratense L.), (ii) crimson clover (Trifolium incarnatum L.), (iii) alfalfa (Medicago sativa L.) and (iv) winter fallow. The plots were split into two rates of fertilizer N (0 and 90kg Nlha) in a split-plot experimental plan. Compared with fallow treatment, legumes depleted soil water in the surface 15cm at corn planting by 17 to 26%. As a result, corn emergence was markedly delayed with legume residues by 8 to 11 days. Corn silage DM yield was significantly reduced in the presence of legume residues by 2.0 to 3.4 and 1.5 to 2.5 tonlha compared with winter fallow treatment at 0 and 90kg fertilizer Nlha, respectively, but no significant difference in the corn DM yield was found between legume residue treatments. There was an overall tendency for increased corn yields with 90kg fertilizer Nlha compared to Okg fertilizer Nlha, although not all yield increases were significantly greater. The corn yield response to applied N suggests that a source of N from legume residues was not sufficient for a succeeding corn crop. There was significantly more N (P

• Restorative Dentistry and Endodontics
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• 제39권1호
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• pp.63-67
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• 2014

This is a case report of chronic maxillary sinusitis caused by root canal overfilling of Calcipex II (Techno-Dent). A 60 year-old male complained of dull pain in the right maxillary molar area after complicated endodontic treatment using Calcipex II paste and was finally diagnosed with a chronic maxillary sinusitis through a clinical and radiological observation. In the biopsy examination, the periapical granuloma contained a lot of dark and translucent Calcipex II granules which were not stained with hematoxylin and eosin. They were usually engulfed by macrophages but rarely resorbed, resulting in scattering and migrating into antral mucosa. Most of the Calcipex II granules were also accumulated in the cytoplasms of secretory columnar epithelial cells, and small amount of Calcipex II granules were gradually secreted into sinus lumen by exocytosis. However, chronic granulomatous inflammation occurred without the additional recruitment of polymorphonuclear leukocytes (PMNs) and lymphocytes, and many macrophages which engulfed the Calcipex II granules were finally destroyed in the processes of cellular apoptosis. It is presumed that Calcipex II granules are likely to have a causative role to induce the granulomatous foreign body inflammation in the periapical region, and subsequently to exacerbate the chronic maxillary sinusitis in this study.

• The Journal of Advanced Prosthodontics
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• 제14권3호
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• pp.143-149
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• 2022

PURPOSE. Masticatory loading triggers active bone remodeling, altering alveolar bone mineral density (BMD). While dental implants are placed to bear masticatory loading, their influence on changing bone properties has not been fully investigated. Objective of this pilot study was to examine whether the dental implantation has an effect on BMD distribution of bone by comparing dentate, edentulous, and edentulous patients with implants. MATERIALS AND METHODS. Cone beam computed tomography (CBCT) images of 19 partially edentulous patients (Dent), 19 edentulous patients (Edent), and 16 edentulous patients who received implants in the mandible (Edent+Im), were obtained. CBCT images were also obtained from 5 patients within Edent+Im group, before implant placement and after implant loading. Basal cortical bone region of the mandible was digitally isolated. A histogram of gray levels proportional to BMD was obtained to assess mean, histogram standard deviation (HSD), fifth percentile of low and high values (Low₅ and High₅) of the BMD distribution. Multivariate analysis of variance and paired t-test were used to compare the BMD parameters among the 3 dental status groups and between pre- and post-implantation, respectively. RESULTS. Edentulous patients with implants had significantly greater HSD and High₅ values compared to edentulous patients (P < .013). All other comparisons were not significant (P > .097). Mean, HSD, and High₅ values significantly increased after receiving implants (P < .022). CONCLUSION. The current findings suggested that receiving dental implants promoted oral bone mineralization for edentulous patients. The longitudinal investigation could provide valuable information on understanding the effects of implantation on the behavior of oral bone quality.

• Journal of Korean Dental Science
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• 제15권1호
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• pp.61-67
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• 2022

Purpose: This study aimed to evaluate the accuracy of bite registration using intraoral scanner based on data trimming strategy for fremitus teeth. Materials and Methods: A reference model was designed by Medit Model Builder software (MEDIT Corp., Seoul). Tooth number 24 and 25 were separated as dies and tooth number 26 was prepared for full-coverage crown. Those were printed using a 3D printer (NextDent 5100). The scanning procedure was performed by a single trained operator with one intraoral scanner (i700; MEDIT Corp.). The scanning groups were divided as follows: group 1 (G1), no fremitus; group 2 (G2), 0.5 mm buccal fremitus in the maxillary left first and second premolar; and group 3 (G3), 1.5 mm buccal fremitus in the maxillary left first and second premolar. Each group was scanned 10 times and were analyzed using the reference model data. Surface-based occlusal clearance was analyzed at the prepared tooth to evaluate accuracy. Result: Mean values of control group (G1) were 1.587±0.021 mm. G2 showed similar values to those from the control group (1.580±0.024 mm before trimming strategy and 1.588±0.052 mm after trimming strategy). G3 showed significantly greater values (1.627±0.025 mm before trimming strategy and 1.590±0.024 mm after trimming strategy) and the differences were found between trimming strategy (P=0.004). Conclusion: Bite trimming strategy for fremitus teeth is a reliable technique to reduce inaccuracies caused by the mobility at maximum intercuspation.

• Geomechanics and Engineering
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• 제33권1호
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• pp.11-18
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• 2023

This study explores a new energy partitioning approach to determine the fracture toughness of 3-D printed pristine/recycled high density polyethylene (HDPE) blends employing the essential work of fracture (EWF) concept. The traditional EWF approach conducts a uniaxial tensile test with double-edge notched tensile (DENT) specimens and measures the total energy defined by the area under a load-displacement curve until failure. The approach assumes that the entire total energy contributes to the fracture process only. This assumption is generally true for extruded polymers that fracture occurs in a material body. In contrast to the traditional extrusion manufacturing process, the current 3-D printing technique employs fused deposition modeling (FDM) that produces layer-by-layer structured specimens. This type of specimen tends to include separation energy even after the complete failure of specimens when the fracture test is conducted. The separation is not relevant to the fracture process, and the raw experimental data are likely to possess random variation or noise during fracture testing. Therefore, the current EWF approach may not be suitable for the fracture characterization of 3-D printed specimens. This paper proposed a new energy partitioning approach to exclude the irrelevant energy of the specimens caused by their intrinsic structural issues. The approach determined the energy partitioning location based on experimental data and observations. Results prove that the new approach provided more consistent results with a higher coefficient of correlation.

• 한국식품영양과학회지
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• 제39권6호
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• pp.843-852
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• 2010

옥수수를 이용한 고품질의 가공식품을 개발하기 위한 연구의 일환으로 옥수수의 품종별 및 가열처리에 따른 기능성 폴리페놀화합물인 hydroxycinnamic acid derivatives(HADs) 및 안토시아닌 색소의 함량 변화를 조사하였다. 국내산 3가지 옥수수 품종(찰옥수수, 감미옥수수 및 사료용 옥수수)의 일반성분 함량을 측정한 결과, 수분함량은 4.13~10.07%, 무질소화합물 65.57~81.75%, 단백질 6.51~15.15%, 지방 3.16~12.35%, 섬유소 2.09~7.81%, 회분 1.40~1.96% 범위로, 찰옥수수의 일반성분의 함량은 비슷하였으나 감미종 옥수수는 찰옥수수보다 단백질과 지방 함량이 높은 반면, 당 함량은 낮았으며, 특히 감미종 중 감미옥 품종은 지방과 섬유소 함량이 옥수수 품종 중 가장 높은 함량을 나타내었고, 사료용 옥수수는 단백질 및 지방 함량이 매우 낮았으며, 특히 단백질 함량은 옥수수 품종 중 가장 낮았다. 옥수수 품종 중 찰옥수수는 5가지 HADs 함량이 골고루 분포하고 있는 반면, 사료용 옥수수는 2가지 FCAs의 함량은 낮은 반면, 3가지 PCs 함량이 가장 높았으며, 특히 P3394 품종이 가장 높았다. 감미 옥수수는 찰옥수수보다 FCAs의 함량은 대체로 높은 반면, PCs는 사료용보다 적어 대체로 찰옥수수와 사료용 옥수수의 중간 정도의 HADs 함량을 나타내었다. 찰옥수수 품종 중 박사찰옥수수의 총 안토시아닌 색소 함량은 2.03 mg/g(건물중), 알록이찰옥수수는 3.43 mg/g, 그리고 흑찰옥수수의 함량은 4.35 mg/g으로서 흑미백찰옥수수의 총 안토시아닌 색소 함량이 가장 높았다. 가열처리에 따라 흑찰옥수수의 2가지 FCAs는 다소 증가한 반면, 3가지 PCs는 거의 변화가 없었으며, 가열처리 중 볶음, retort 및 팽화처리는 FCAs를 증가시켰고 특히 팽화처리 시 크게 증가하였다. 가열처리에 따른 흑찰옥수수의 총 안토시아닌 색소 함량을 측정한 결과, 대조구 함량은 4.35 mg/g이었으나 retort 처리(4.45 mg/g) 경우를 제외하고 대부분 가열처리에 따라 함량이 감소하는 경향을 나타내었으며, 특히 팽화처리 경우 안토시아닌 함량이 크게 감소하여 거의 소실되었다. 흑미백찰옥수수로부터 주된 안토시아닌 색소인 pelargonidin 3-glucoside(P3G)를 분리 및 동정하였으며, 가열처리에 따른 P3G의 함량 변화를 측정한 결과, retort 처리 경우 함량이 다소 증가한(20.03 mg%) 반면, 그 외 볶음, 마이크로파 및 압출성형 처리에 의해 대체로 감소하였으며, 특히 팽화처리 경우 색소가 거의 소실되었다. 이러한 결과를 종합해 볼 때 옥수수의 기능성성분인 HADs 및 안토시아닌 색소 함량은 옥수수 품종 및 가공처리에 따라 다소 달라짐을 알 수 있었으며, 특히 옥수수 품종 중 항암, 항고혈압, 항당뇨 및 항노화성 FCAs 및 안토시아닌 색소 함량이 높은 흑찰옥수수의 대량 보급과 더불어 고압가열처리(retort)에 의한 고품질의 흑찰옥수수 가공품 개발이 요구된다.

• 생명과학회지
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• 제18권11호
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• pp.1561-1569
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• 2008

본 연구는 옥수수 수입원과 steam flake 처리에 따른 in situ 건물 분해율 및 보관기간별 mycotoxins 함량을 조사하기 위하여 수행되었다. 미국과 인도산 옥수수(yellow dent corn)를 공시재료로 하여, steam flake 처리 효과에 대해 조사하였다. 시험구는 총 4개의 처리구(USCW, 미국산 무처리 옥수수; USCF, 미국산 steam flaking 옥수수; IDCW, 인도산무처리 옥수수; IDCF, 인도산 steam flaking 옥수수)를 두고, 각 처리구당 보관기간(0, 1, 2, 3, 4, 5, 6, 7, 8주)별 4반복으로 수행되었다. In situ 시험을 위해서 반추위 누관이 장착된 Holstein 수소 2두가 이용되었고, 공장환경분야 표준상태 (STP, standard temperature and pressure, $25^{\circ}C$ 1 atm.)에서 보관기간 동안 매주, 곰팡이 독소인 aflatoxin과 ochratoxin의 농도를 측정하였다. 옥수수의 반추위 내 발효시간별 in situ 건물 소실율은 무처리구에서는 미국산이 인도산보다 약 $3.0{\sim}44.1%$ 높았으나, steam flaking 처리를 함으로써 건물소실율의 차이가 없어졌다. 미국산 옥수수는 무처리 알곡의 건물 분해율이 높은 편이었으나, flake처리에 의한 영향이 적은 반면, 인도산 옥수수는 무처리 알곡의 건물 분해율은 낮은 편이지만 flake 처리를 하였을 때, 분해율이 크게 증가되었다. 미국산 옥수수와 flake 처리 옥수수의 aflatoxin 함량은 보관기간 동안 매우 낮은 수준이었으나, 인도산 옥수수 알곡을 6주 이상 보관할 경우, 허용기준치를 초과하였다. 따라서 인도산 옥수수 알곡을 장기보관 해야 할 경우, steam flake 처리를 하는 것이 aflatoxin 오염방지를 위해서 필수적이며, 알곡으로 보관할 경우는 6주 이상을 넘기지 않는 것이 중요할 것으로 사료된다.

• Journal of Animal Science and Technology
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• 제52권5호
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• pp.441-448
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• 2010

본 연구는 파종시기와 재배일수가 사일리지용 옥수수의 생육특성, 수량성 및 사료적 가치를 규명하기 위하여 실시하였으며, 시험구 처리는 파종시기를 5월 1일(T1), 5월 8일(T2), 5월 15일(T3), 5월 22일(T4) 및 5월 29 (T5)일로 하고 수확 시기는 일괄 8월 24일로 실시하였다. 따라서 재배기간은 T1, T2, T3, T4 및 T5구가 각각 115, 108, 101, 94, 87일로 난괴법 5처리 3반복으로 하였다. 수확시 숙기는 T1, T2, T3, T4 및 T5구가 각각 황숙기, 황숙기 초기, 호숙기 말기, 호숙기, 호숙기 초기 상태였다. 생육특성에 있어서 초장과 근계 발생(1, 2, 3, 4 차근 발생 정도)은 T5구가 유의적으로 높게 나타났으며(P<0.01). 엽장은 T4구에서(P<0.05), 고사엽, 알곡충실도 암이삭 둘레는 T1구가 다른 구에 비하여 유의적으로 높게 나타났다(P<0.05, 0.01). 그러나 엽폭, 착수고, 엽수, 암이삭 길이, 경의 굵기, 경경도 및 당도에 있어서는 상호 처리 간 유의적인 차이를 보이지 않았다. 건물 및 TDN 수량은 파종시가 빠르고 재배기간이 길었던 T1 > T2 > T3 > T4 > T5구 순으로 높게 나타났다(P<0.01). 조단백질, 조회분, NDF, ADF, 조섬유 함량은 T4구가 유의적으로 높게 나타났으며(P<0.05, 0.01) 조지방 함량은 T1구에서 유의적으로 높게 나타났다(P<0.01). 총 필수아미노산 함량은 T4 > T3 > T1 > T2 > T5 순으로 총 비필수아미노산 함량은 T1 > T4 > T2 > T3 > T5 순으로 총 아미노산 함량은 T4 > T1 > T3 > T2 > T5구 순으로 나타났지만 이들 처리구간에는 유의적 차이는 나타나지 않았다. 총불포화지방산, 총포화지방산 함량은 T1구에서 가장 높은 경향을 보였다(P<0.01). 그리고 총불포화지방산/포화지방산의 비율은 T1 > T2 > T3 > T4 > T5구 순으로 나타났다. 무기물성분은 T4구가 4,721.25 mg/100 kg으로서 가장 높았던 반면 T2구는 2,970.80 mg/kg으로서 다른 구에 비하여 가장 낮은 수치를 보였다(P<0.05). 이상 결과를 종합해 볼 때 논토양에서 사일리지용 옥수수 재배는 5월 초순에 파종하여 황숙기에 수확 하는 것이 건물수량과 영양수량 생산에 유리한 것으로 판단된다.