• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.856-861
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• 2010

In recent days, the safety of the levee has been an issue because the levee has become bigger according to the Four-river Restoration Project and so on. The greater part of the levee damage has occurred in the interface between soils and the structures. Specially, the drainage construction crosses the levee keeps its settlement down in order to secure a grade of drainage. However, when the settlement isn't generated by using foundation such as pile, the levee is more likely to have leakage at the interface because the construction doesn't behave with soils. In our study, therefor, testing of the behavior of the levee having the drainage construction was carried out to clarify the effects of the foundation type of drainage construction.

• 치위생과학회지
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• 제11권4호
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• pp.333-337
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• 2011

본 실험에서는 광중합형 임시충전재의 사용기간(1일 후, 3일 후, 7일 후)동안 구강 내의 수분과 온도변화 및 교합력에 의한 미세누출의 가능성을 알아보기 위하여 무게 및 압축강도를 측정하고 열 순환 횟수에 따라 충전재와 와동면 사이의 미세누출을 평가하고자 2종의 광중합형 임시충전재를 사용하여 실험한 결과는 다음과 같다. 1. 광중합형 임시충전재는 사용기간에 따라 측정한 무게는 증가되었다. 제품 간의 비교결과는 Quicks의 무게가 더 높게 나타났다. 2. Spacer의 압축강도는 사용기간에 따라 유의한 차이가 있으나 Quicks의 압축강도에서는 유의한 차이가 나타나지 않았다. 유의한 차이를 보인 Spacer에서는 3일차에서 압축강도가 크게 증가되었다. 3. 열 순환 횟수에 따른 미세누출은 7,000번 실시한 군에서 미세노출이 가장 높게 나타났고, 1,000번 실시한 군과 3,000번 실시한 군은 7,000번 실시한 군보다 통계학적으로 낮은 미세누출을 나타내었다. 4. 사용기간에 따른 무게와 압축강도 및 미세누출사이의 상호연관성이 나타났다. 본 연구에서는 사용기간 경과에 따라 미세누출의 증가를 가져왔으나 수복 후 시간이 경과함에 따라 미세누출이 증가하는 것은 자명한 사실이므로 향후 광중합형 임시충전재의 미세누출을 평가를 위해서는 습식분석을 통하여 화학적 결합을 유도하는 재료의 조성을 분석하는 방법을 부여하는 것이 미세누출 평가에 적절하다고 사료된다.

• 터널과지하공간
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• 제27권6호
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• pp.343-350
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• 2017

최근 도심지 지상공간의 포화로 전세계적으로 지하공간개발이 활발히 진행되고 있으며, 지상 및 지하구조물에 인접하여 굴착이 많이 이루어지고 있다. 굴착공사 중 시공 부주의나 시공기술 미흡, 지하수 유출, 급격한 지층의 변화, 토류 시스템 구성품의 문제 등으로 인해 각종 지반함몰 사고가 발생하여 사회적 이슈로 부각되고 있다. 국가적으로 이를 대응하기 위하여 도심지 지하 시설물에 대한 예방중심의 선제적 재난 재해 관리 및 신속 복구 시스템 구축을 추진 중에 있다. 본 연구에서는 굴착공사 시 지반 내부적인 변화 요소(지하수위 변화, 지하매설물 손상 등)와 외부적인 변화요소(차량하중, 지진, 지반굴착 등)를 고려한 지하안전 확보를 위한 기술개발 동향에 대하여 자료를 수집하였다. 지반거동 해석 및 지반함몰 평가기술과 지반함몰 예방을 위한 안전한 굴착 및 보강기술, 지반함몰 발생시 긴급복구 기술의 개선 및 국내 자립화가 요구되고 있는 가운데 현재 도심지 굴착공사시 지반함몰 예방을 위한 기술개발 현황에 대하여 소개하고자 한다. 현재 연구가 진행되고 있는 부분도 있으나 크게 분류하여 예측/평가기술, 복합탐사기술, 차수보강기술, 긴급복구기술, 굴착기술의 5개 분야로 설명하고자 한다.

• Restorative Dentistry and Endodontics
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• 제26권1호
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• pp.16-22
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• 2001

The purpose of this study was to evaluate the marginal microleakage of condensable composite resin restorations according to flowable resin lining of internal cavity wall. The eighty extracted human molar teeth without caries and/or restorations are used The experimental teeth were randomly assigned into four groups of ten teeth each. Eighty caries-free extracted human molars were used in this study. The conventional class II cavities (box-shaped on mesial and distal surface, faciolingual width : 3mm, gingival wall depth : 1.5mm) were prepared 1mm below cementoenamel junction with a # 701 carbide bur. The teeth were divided into four groups, and then each group were subdivided into A & B group according to flowable resin & compomer lining ; Group 1-A : Tetric Ceram filling, Group 1-B : Tetric Flow lining and Tetric Ceram filling, Group 2-A Ariston pHc filling, Group 2-B : Tetric Flow lining and Ariston pHc filing, Group 3-A SureFil filling, Group 3-B : Dyract Flow lining and SureFil filling, Group 4-A : Pyramid filling, Group 4-B : Aeliteflo lining and Pyramid filling. To simulate as closely as possible the clinical situation during retoration placement, a "restoration template" was fabricated, and the condensable resin was filled using a three-sited light-curing incremental technique. All the materials used were applied according to the manufacturers' instructions. The specimens were stored in the 100% humidity for 7 days prior to thermocycling (100 thermal cycles of 5~55$^{\circ}C$ water with a 30-second dwell time) The specimens were immersed in 2% metyleneblue dye for 24 hours, and then embedded in transparent acrylic resin and sectioned mesiodistally with diamond wheel saw. The degree of marginal leakage was scored under stereomicroscope ($\times$20) and the data were analyzed by Kruskal-Wallis test and Wilcoxon signed ranks test. The results were as follows : 1. In the gingival margins of all the group, microleakage of subgroup B was less than subgroup A. 2. In the group 1, 2, 4, there was significant differences between subgroup A and B (p<0.05), but in the group 3, there was not significant different between group 3-A (SureFil) and group 3-B (Dyract flow/SureFil) (p>0.05). 3. In the subgroup A and B, there was significant different between all group except group 4 of subgroup A. From the results above, it was suggested that the cavity lining of flowable resin and flowable compomer in condensable resin restoration decrease microleakage at gingival margin, and does improve their ability to seal the gingival margin of class II preparation.

• Restorative Dentistry and Endodontics
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• 제25권2호
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• pp.299-308
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• 2000

The purpose of this in vitro study was to evaluate the microleakage of 5 curing methods in class V composite restorations which are composed of two-step light curing, pulse-delay cure, low curing-light intensity, moderate curing-light intensity and high curing-light intensity. In this study, class V cavities were prepared on buccal and lingual surfaces of 50 extracted human upper or lower molars on cementum margin. Single Bond adhesive and Z-100 shade A2 were applied for each group following the manufacture's instruction. The experimental teeth were randomly divided into 5 groups of 10 samples (20 surfaces) each. Group 1: two-step light curing; Group 2: pulse-delay cure; Group 3: low curing-light intensity; Group 4: moderate curing-light intensity; Group 5: high curing-light intensity. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen was then observed with a stereomicroscope at ${\times}20$. The composite resin/tooth interfaces were examined under Scanning Electron Microscopy. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA and Dunn's Method. The results of this study were as follows. 1. In all groups, the leakage values seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 2. No group in this study showed significant differences in leakage values at both the enamel and the dentin margins(P<0.05). 3. In all groups, the gaps seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 4. The gaps in this study showed significant differences and two-step light-curing and low curing-light intensity produced significant less gap than high curing-light intensity(P<0.05).

• 대한토목학회논문집
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• 제29권5C호
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• pp.217-228
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• 2009

실제 폐기물 매립지의 누출 복원을 위해 전기영동기법을 적용할 경우, 핵심적으로 우선 고려해야 할 사항은 실제 침출수 전해질 환경에서 전기영동력에 의한 입자의 이동 및 누출구 복원 가능성을 판단하는 것이다. 하지만 침출수의 다양한 화학적 성분과 점토 입자와의 상호작용에 의한 점토입자들의 응집현상은 전기영동기법의 적용시키는데 큰 문제를 유발시킨다. 이에 따라 본 연구에서는 점토 입자의 응집에 영향을 미치는 침출수내 화학종과 그 범위를 파악하고자 1차원 중력침강실험과 전기영동 실험을 수행하였다. 또한 각각의 침강속도와 제타포텐셜, 전기영동적 이동속도 개념을 적용하여 침출수의 화학종과 그 농도에 따른 입자 거동 특성을 분석하였다.

• 한국전자파학회논문지
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• 제26권3호
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• pp.292-299
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• 2015

본 논문에서는 3-레벨 인코딩 기법을 적용하여 시스템의 효율과 선형성을 개선할 수 있는 새로운 구조의 EER 송신기를 제안하였다. 제안된 송신기는 첨두 전력 대 평균 전력비에 상관없이 동일한 크기의 신호만을 증폭하고, 채널대역 내의 양자화 노이즈를 감소시켜 높은 효율을 얻을 수 있으며, 포락선 신호와 위상 신호 간 시간 부정합 특성을 개선하여 높은 선형성을 가질 수 있도록 하였다. 130 nm CMOS 공정으로 제작된 송신기 칩은 8.5 dB의 첨두 전력 대 평균전력비를 갖는 LTE 20 MHz 신호에 대해 2.13 GHz의 반송주파수에서 3.7 %의 오류 벡터 크기와 37.5 dBc의 인접 채널 누설비 특성을 보인다.

• 한국환경복원기술학회지
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• 제3권1호
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• pp.38-51
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• 2000

This study seeks to present creation techniques increasing biodiversity while excluding techniques that avoid rooftop as a place for revegetation or techniques that are standardized and ecologically undesirable. To this end, a theoretical study was conducted including the identification of issues that need to be considered in introducing biotope creation techniques at a rooftop space using eco-pond or eco-park creation techniques. Based on the result, a creation process and techniques were presented for the rooftop of Kyungdong Energy Company building located in Bundang, Sungnam city. The conclusions reached in this study are as follows. First, when structural problems such as load or leakage are resolved and when it is planned as a habitat within a range of carrying load, a rooftop may be habitats for various organisms. Second, same creation techniques for eco-ponds or eco-parks may be applied to create biotope in a rooftop. In fact, the introduction of a wetland ecosystem on a rooftop may contribute significantly in increasing biodiversity. In addition, it would be desirable to approach traditional rooftop revegetation methods in an ecological aspect and to introduce indigenous plants and to offer habitats to insects and birds. Third, in order to create rooftop biotope, there should be enough studies and experiments on resolving structural problems and on techniques or technologies to create habitats. Since the Kyongdong Energy Company rooftop biotope described in this study is the first experimental site in Korea, it requires a series of process to identify problems and to improve them by monitoring the site in the future. Through such studies and experiments, efficient rooftop biotope creation techniques should be developed and disseminated.

• Restorative Dentistry and Endodontics
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• 제26권6호
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• pp.464-484
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• 2001

When restoring a tooth, the dentist tries to choose the ideal material for existing situation. One criterion that is considered is its suitability for restoring coronal strength. As more tooth structure is removed, the cusps are weakened and susceptible to fracture. Further, this increased deformation may cause the formation of intermittent gaps at the margin between the hard tissue and the restoration, facilitating marginal leakage. The improvements in ceramic materials now make it possible for alternatives to amalgams, composites, and cast metal to be of offered for posterior teeth. Of the materials used, ceramics most closely approximates the properties of enamel. The introduction of computer-aided design/computer-aided manufacture(CAD/CAM) systems to restorative dentistry represents a major technological breakthrough. It is possible to design and fabricate ceramic restorations at a single appointment. Additionally, CAD/CAM systems eliminate certain errors and inaccuracies that are inherent to the indirect method and provide an esthetic restoration. The aim of this investigation was to study the loading characteristics of CAD/CAM ceramic inlay and to compare the stress distribution and displacement associated with different designs of cavity(the isthmus width and cavity depth). A human maxillary left first premolar was prepared with standard mesio-occlusal cavity preparation, as recommended by the manufacturer Ceramic inlay was fabricated with CEREC 2 CAD/CIM equipment and cemented into the prepared cavity. Three dimensional model was made by the serial photographic method. The cavity width was varied $\frac{1}{3}$, $\frac{1}{2}$ and $\frac{2}{3}$ of intercuspal distance between buccal and lingual cusp tip. The cavity depth was varied 1.5mm and 2.3mm. So six models were constructed to simulate six conditions. A point load of 500N was applied vertically onto the first node of the lingual slope from the buccal cusp tip. The stress distribution and displacement were solved using ANSYS finite element program(Swanson Analysis System). (omitted)

• Journal of Korean Neurosurgical Society
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• 제47권3호
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• pp.199-202
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• 2010

Objective : Balloon kyphoplasty is a minimally invasive procedure that is mainly performed for refractory pain due to osteoporotic compression fractures. The purpose of this study was to evaluate the results of balloon kyphoplasty performed at different times after an injury. Methods : In this retrospective study, the records of 99 patients who underwent one level of balloon kyphoplasty between January 2005 and December 2007 were reviewed. The patients were divided into three groups : 21 patients treated within 3 weeks of an injury (the acute group), 49 treated within 3 weeks to 2 months of an injury (the subacute group), and 29 patients treated at more than 2 months after an injury (the chronic group). Clinical outcomes were assessed using a visual analogue scale (VAS). In addition, modified MacNab's grading criteria was used to assess the subjective patient outcome. The radiology findings, including vertebral height restoration and procedure related complications, were analyzed based on the different time intervals after the injury. Results : Patients in all three groups achieved marked pain relief in terms of the VAS within 7 days of the procedure. Good or excellent results were achieved by most patients in all three groups. However, the height restoration, the main advantage to performing a balloon kyphoplasty, was not achieved in the chronic group. Moreover, evidence of complications including cement leakage was observed significantly less frequently in the subacute group compared to the other two groups. Conclusion : Although balloon kyphoplasty is an effective treatment for osteoporotic compression fractures, with regard to pain relief, the subacute stage appears to be optimal for treating patients with a balloon kyphoplasty in terms of achieving the best outcomes with minimal complications.