• 구강회복응용과학지
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• 제24권3호
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• pp.299-310
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• 2008

경부골 최대응력을 안정적으로 산출하기 위해서, 경부 디자인 형상이 비교적 단순한 메가젠 임플란트 모델을 대상으로, 유한요소 모델링을 통하여 경부골의 응력분포를 계산하였다. 그리고 산출된 응력분포를 회귀분석법으로 통계 처리하여 응력 집중점의 응력을 정량화 하였다. 결과는 모든 모델에서 경부골 응력은 치밀골 외면에 집중되었으며, 그 범위는 0.5mm 이내였다. 회귀분석법을 활용하기 위해서는 mesh 정밀도가 높아야 했으며, 이 경우 특이점의 최대 응력을 안정적으로 산출 할 수 있었다.

• 한국산림과학회지
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• 제94권4호통권161호
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• pp.258-263
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• 2005

경남 거제지역에 자생하고 있는 붉은고로쇠나무의 흉고직경급에 따른 수액채취량과 성분을 분석하였다. 붉은고로쇠나무의 수액채취 가능기간은 17일간이었으며, 총수액채취량은 60본에서 193 l이었다. 총수액채취량에 대해 각 20본의 소 중 대경목이 각각 40 l(21%), 49 l(25%), 104 l(54%)가 채취되어 흉고직경이 증가할수록 수액채취량이 많아지는 경향을 나타내었다. 이는 수관폭과 근계발달에 기인하는 것으로 추정된다. 수액채취량은 주야간의 온도격차가 클 때 많은 것으로 나타났다. 붉은고로쇠나무 수액의 pH, 고형분, 당도는 각각 6.5, 2.40%, 1.99%로 측정되었으며, 유리당은 자당 함량이 19.9 g/L가 검출되었으나 포도당, 과당, 맥아당은 검출되지 않았다. 붉은고로쇠나무 수액은 총 7종의 무기성분이 검출되었으며 Ca과 Mg의 함량이 각각 441 mg/l 383 mg/l으로 나타났다.

• 터널과지하공간
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• 제29권6호
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• pp.425-438
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• 2019

본 연구에서는 일정한 방향의 층리가 발달한 퇴적암에 굴착된 지하철 병설터널을 모델링하여 축소모형 실험을 실시하였다. 연구대상 터널의 규격은 6.2 m×6.8 m이고 필러 폭은 4 m이다. 차원해석을 통해 현장암석에 적합한 모형재료를 선정하였고, 이를 사용하여 이방성 모형시험체를 제작하였으며 이축압축시험을 통해 터널의 파괴 및 변형거동을 알아보았다. 모형시험체에 하중을 증가시킴에 따라 필러의 중앙부에서 병설터널 사이를 가로지르는 최초의 균열이 발생하였고, 터널 천정부와 바닥부에서도 점차 파괴가 진행되었다. 필러부의 모든 균열은 기존의 층리면을 따라 발생하여 암반의 층리면이 필러 파괴의 주요 원인으로 나타났다. 또한, FLAC의 유비쿼터스 절리모델을 사용하여 실험 조건에 대한 수치해석을 실시함으로써 실험의 결과를 검증해 보았다. 여기서 얻어진 소성영역의 분포경향은 모형실험의 결과와 대체로 부합하여 실험의 신뢰성을 확인하였다.

• 한국농공학회논문집
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• 제52권3호
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• pp.39-45
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• 2010

Quantification of carbon absorption and understanding the human induced land use changes (LUC) forms one of the major study with respect to global climatic changes. An attempt study has been made to quantify the carbon absorption by LUC through remote sensing technology. The Landsat imagery four time periods was classified with the hybrid classification method in order to quantify carbon absorption by LUC. Thereafter, for estimating the amount of carbon absorption, the stand biomass of forest was estimated with the total weight, which was the sum of individual tree weight. Individual tree volumes could be estimated with the crown width extracted from digital forest cover type map. In particular, the carbon conversion index and the ratio of the $CO_2$ molecular weight to the C atomic weight, reported in the IPCC guideline, was used to convert the stand biomass into the amount of carbon absorption. Total carbon absorption has been modeled by taking areal estimates of LUC of four time periods and carbon factors for land use type and standing biomass. Results of this study, through LUC suggests that over a period of construction, 7.10 % of forest and 9.43 % of barren were converted into urban. In the conversion process, there has been a loss of 6.66 t/ha/y (7.94 %) of carbon absorption from the study area.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제43권2호
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• pp.70-76
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• 2017

The purpose of this study was to perform a literature review of short implants in the posterior maxilla and to assess the influence of different factors on implant success rate. A comprehensive search was conducted to retrieve articles published from 2004 to 2015 using short dental implants with lengths less than 10 mm in the posterior maxilla with at least one year of follow-up. Twenty-four of 253 papers were selected, reviewed, and produced the following results. (1) The initial survival rate of short implants in the posterior maxilla was not related to implant width, surface, or design; however, the cumulative success rate of rough-surface short implants was higher than that of machined-surface implants especially in performance of edentulous dental implants of length <7 mm. (2) While bone augmentation can be used for rehabilitation of the atrophic posterior maxilla, short dental implants may be an alternative approach with fewer biological complications. (3) The increased crown-to-implant (C/I) ratio and occlusal table (OT) values in short dental implants with favorable occlusal loading do not seem to cause peri-implant bone loss. Higher C/I ratio does not produce any negative influence on implant success. (4) Some approaches that decrease the stress in posterior short implants use an implant designed to increase bone-implant contact surface area, providing the patient with a mutually protected or canine guidance occlusion and splinting implants together with no cantilever load. The survival rate of short implants in the posterior edentulous maxilla is high, and applying short implants under strict clinical protocols seems to be a safe and predictable technique.

• The Journal of Advanced Prosthodontics
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• 제5권2호
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• pp.187-197
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• 2013

PURPOSE. The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns. MATERIALS AND METHODS. Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively. To simulate masticatory force, loads of 280 N were applied from three directions (vertical, at a $45^{\circ}$ angle, and horizontal). To simulate maximum bite force, a load of 700 N was applied vertically to the crowns. Maximum principal stress (MPS) was determined for each model, loading condition, and position. RESULTS. In the maximum bite force simulation test, the MPSs on all crowns observed around the shoulder region and loading points. The compressive stresses were located in the shoulder region of the veneer-zirconia interface and at the occlusal region. In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally. MPS increased in the shoulder region as the shoulder height increased. CONCLUSION. This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.

• 한국수정란이식학회지
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• 제30권1호
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• pp.51-57
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• 2015

This study was aimed to determine the biometry of genital organs, incidence of gynecological disorders and pregnancy loss in Black Bengal goat (Capra hircus). Genitalia of 118 does were collected from local abattoirs. Biometric parameters of genital organs were measured and gross and histopathological examinations were carried out for detection of abnormalities. For gravid uterus, age of the fetus was determined by measuring crown-rump length. There was no significant difference in the length, width and weight of right and left ovaries (P>0.05). However, the number of follicles between left ($5.3{\pm}2.3$) and right ovaries ($7.4{\pm}2.7$) varied significantly (P<0.05). The mean length of right fallopian tube and uterine horn were not varied with those of left fallopian tube and uterine horn. The length of uterine body, cervix and vagina were $1.3{\pm}0.1cm$, $3.3{\pm}0.5cm$ and $6.8{\pm}1.3cm$, respectively. Overall, 29 (24.6%) genitalia had abnormalities. Fifteen genitalia (12.7%) had ovarian abnormalities including ovaro-bursal adhesions (6.8%), parovarian cyst (5.1%) and follicular cyst (0.9%). Uterine abnormalities were found in 12 genitalia (10.2%) and predominant uterine lesion was endometritis (6.8%) followed by adenomyosis (1.7%), hemorrhagic lesion on endometrial surface (0.9%) and cyst in broad ligament (0.9%). In addition, cyst in fallopian tube (0.9%) and vagina (0.9%) were recorded. The proportion of slaughtered pregnant goats was 15.3% (18/118). The pregnancy wastage was highest in the first month (50.0%) followed by second (33.3%) and third (16.7%) month. It can be concluded that ovaro-bursal adhesions, parovarian cyst and endometritis are the gynecological disorders of major concern in Black Bengal goat.

• The Journal of Advanced Prosthodontics
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• 제13권1호
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• pp.46-54
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• 2021

Purpose. The design of the implant-abutment complex is thought to be responsible for marginal bone loss (MBL) and might affect the condition of the peri-implant tissues. This the present study aimed to evaluate the influence of the implant-abutment complex on MBL and the peri-implant tissues in partially edentulous patients treated with dental implants and determine the most advantageous design. Materials and Methods. A total of ninety-one endosseous implants with different designs of implant-abutment complex [tissue level-TL (n = 30), platform switch-PS (n = 18), and platform match-PM (n = 43)] were reviewed for MBL, Probing Pocket Depth (PPD) and Bleeding on Probing (BoP). MBL was calculated for first year of the insertion and the following years. Results. The median MBL for the PM implants (2.66 ± 1.67 mm; n = 43) in the first year was significantly higher than those for the other types (P=.033). The lowest rate of MBL (0.61 ± 0.44 mm; n = 18) was observed with PS implants (P=.000). The position of the crown-abutment border showed a statistically significant influence (P=.019) and a negative correlation (r=-0.395) on MBL. BoP was found significantly higher in PM implants (P=.006). The lowest BoP scores were detected in PS implants, but the difference was not significant (P=.523). The relation between PPD and connection type revealed no statistically significant influence (P>.05). Conclusion. Within the limitations of the present study, it may be concluded that PS implants seem to show better peri-implant soft tissue conditions and cause less MBL.

• 인간식물환경학회지
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• 제24권2호
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• pp.219-227
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• 2021

Background and objective: Urban street trees play an important role in carbon reduction in cities where greenspace is scarce. There are ongoing studies on carbon reduction by street trees. However, information on the carbon reduction capacity of street trees based on field surveys is still limited. This study aimed to quantify carbon uptake and storage by urban street trees and suggest a method to improve planting of trees in order to increase their carbon reduction capacity. Methods: The cities selected were Sejong, Chungju, and Jeonju among cities without research on carbon reduction, considering the regional distribution in Korea. In the cities, 155 sample sites were selected using systematic sampling to conduct a field survey on street environments and planting structures. The surveyed data included tree species, diameter at breast height (DBH), diameter at root collar (DRC), height, crown width, and vertical structures. The carbon uptake and storage per tree were calculated using the quantification models developed for the urban trees of each species. Results: The average carbon uptake and storage of street trees were approximately 7.2 ± 0.6 kg/tree/yr and 87.1 ± 10.2 kg/tree, respectively. The key factors determining carbon uptake and storage were tree size, vertical structure, the composition of tree species, and growth conditions. The annual total carbon uptake and storage were approximately 1,135.8 tons and 22,737.8 tons, respectively. The total carbon uptake was about the same amount as carbon emitted by 2,272 vehicles a year. Conclusion: This study has significance in providing the basic unit to quantify carbon uptake and storage of street trees based on field surveys. To improve the carbon reduction capacity of street trees, it is necessary to consider planning strategies such as securing and extending available grounds and spaces for high-density street trees with a multi-layered structure.

• 농업과학연구
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• 제49권3호
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• pp.483-493
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• 2022

It is important to improve the efficiency of plant breeding and crop yield to fulfill increasing food demands. In plant phenotyping studies, the capability to correlate morphological traits such as plant height, stem diameter, leaf length, leaf width, leaf angle and size of panicle of the plants has an important role. However, manual phenotyping of plants is prone to human errors and is labor intensive and time-consuming. Hence, it is important to develop techniques that measure plant phenotypic traits accurately and rapidly. The aim of this study was to determine the feasibility of point cloud data based on a 3D light detection and ranging (LiDAR) system for plant phenotyping. The obtained results were then verified through manually acquired data from the sorghum samples. This study measured the plant height, plant crown diameter and the panicle height and diameter. The R² of each trait was 0.83, 0.94, 0.90, and 0.90, and the root mean square error (RMSE) was 6.8 cm, 1.82 cm, 5.7 mm, and 7.8 mm, respectively. The results showed good correlation between the point cloud data and manually acquired data for plant phenotyping. The results indicate that the 3D LiDAR system has potential to measure the phenotypes of sorghum in a rapid and accurate way.