• 한국산학기술학회논문지
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• 제21권3호
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• pp.129-136
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• 2020

컷아웃스위치(COS: Cut Out Switch 이하 COS)는 전력계통에서 수용가로 전력을 송배전하기 위해 사용되는 변압기의 입력단에 설치되어 사고전류로부터 변압기를 보호하기 위해 설치되는 보호장치이다. COS는 크게 퓨즈링크와 COS몸체 및 접속부로 구성되어 사고전류시 퓨즈링크의 엘리먼트가 용단되어 사고전류를 차단하는 역할을 한다. COS 퓨즈링크가 용단되어 발생하는 강력한 아크가 화염과 소음을 유발시켜 주변지역 거주자에게 불쾌감 및 공포감을 주며, 아크화염으로 인하여 주변기기의 2차 피해를 유발시킬 수 있다. 본 논문에서는 COS 동작 시 발생되는 아크와 소음 및 보호협조의 문제점을 해결하기 위해 폭발형이 아닌 한류형 COS 퓨즈를 개발하였다. 또한 과전류 차단 기능이 없는 한류형 퓨즈의 단점을 개선하기 위해 퓨즈 엘리멘트, 스트라이커와 COS 퓨즈금구 개발을 통하여 과전류 차단성능의 신뢰성을 향상시켰다. COS의 동작 특성 향상은 퓨즈 엘리멘트의 최적 형상 도출, 스트라이커의 원활한 동작을 위한 동작선의 재질과 두께 및 저항 산정, 그리고 스트라이커와 연계된 하부금구류의 구조 개선을 통하여 수행하였다. 본 연구에서 개발한 COS 퓨즈링크는 공인기관의 시험을 통하여 차단성능과 보호협조 성능을 검증하였다. 시험은 본 연구의 한류형 COS와 기존의 폭발형 비한류형 COS의 비교 시험으로 수행하였다.

• Journal of Chest Surgery
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• 제24권1호
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• pp.54-63
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• 1991

Post-thoracotomy pain is so severe that lead to postoperative complications, such as sputum retention, segmental or lobar atelectasis, pneumonia, hypoxia, respiratory failure due to the patient`s inability to cough, deep breathing and movement. Many authors have been trying to reduce the post-thoracotomy pain, but there is no method of complete satisfaction. In 1974, Nelson and associates introduced the intercostal nerve block using the cryoprobe. The application of cold directly to the nerves causes localized destruction of the axons while preserving the endoneurium and connective tissue, thereby introducing a temporary pain block and able to complete regeneration of intercostal nerves. One hundred and two patients, who undergoing axillary or posterolateral thoracotomy at the Department of Thoracic and Cardiovascular Surgery in Korea University Medical Center between April 1990 and August 1990, were evaluated the effects of cryoanalgesia for the post-thoracotomy pain reduction. The patients were divided into two groups: Group A, control, the patients without the cryoanalgesia[No.=50], Group B, trial, the patients with cryoanalgesia[No.=52]. Before the thorax closed, in the group A, local anesthetics, 2% lidocaine 3cc, were injected to the intercostal nerves[one level with the thoracotomy, one cranial and caudal intercostal level and level of drainage tube insertion]. In the group B, cryoprobe was directly applied for 1 minute at the same level. Postoperative analgesic effects were evaluated by the scoring system which made arbitrary by author: The pain score 0 to 4, The limitation of motion score 0 to 3, The analgesics consumption score 0 to 3, The total score, the sum of above score, 0 to 10. For the evaluation of immediate analgesic effects, the score were evaluated at the operative day, the first postoperative day, the second postoperative day, and the seventh postoperative day. The effects of incision type, and rib cut to the post-thoracotomy pain were also evaluated. The results were as follows; 1. The intercostal block with cryoanalgesia reduced the immediate postoperative pain significantly compare with control group. 2. The intercostal block with cryoanalgesia improved the motion of the operation side significantly compare with control group. 3. The intercostal block with cryoanalgesia reduced the analgesics requirements at the immediate postoperative periods significantly. 4. The intercostal block with cryoanalgesia lowered the total score significantly compare with control group. 5. The intercostal block with cryoanalgesia were more effective to the mid-axillary incision than to the posterolateral incision 6. The intercostal block with cryoanalgesia were more effective to the patients without rib cut than to the patients with rib cut. 7. No specific complication need to be treated were not occurred during follow-up.

• 멤브레인
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• 제26권3호
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• pp.220-228
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• 2016

비용매 유도 상분리(NIPS) 법으로 제조된 폴리이미드 전구체를 이용하여 탄소분자체 중공사 분리막을 제조하였으며, 온도변화에 따른 열처리 조건이 탄소분자체 중공사막의 기체 분리 특성에 미치는 영향을 고찰하였다. 열처리 온도 $250{\sim}450^{\circ}C$에서 승온 속도, 안정화 시간을 조정하여 최적화 하였을 때, 중공사 분리막의 단일기체 $N_2$, $SF_6$, $CF_4$ 투과도는 각각 20, 0.32, 0.48 GPU이었고, $N_2/SF_6$ 선택도는 62, $N_2/CF_4$ 선택도는 42로 가장 높은 값을 나타내었다. $SF_6/CF_4/N_2$ 혼합기체 평가에서는 0.5 MPa에서 stage cut이 0.2일 때, $SF_6$, $CF_4$ 회수율이 각각 99, 98% 이상으로 높게 나타났고, 농축농도는 stage cut 0.8에서 주입농도의 4.5배 이상이었다. 이로부터 제조된 탄소분자체 중공사 분리막은 불화가스 회수용 분리막으로써 우수한 소재임을 확인할 수 있었다.

• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.107-119
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• 1990

The purpose of this study was to evaluate the marginal adaptability of the amalgam restorations in applying the cavity varnish (Copalite$^{(R)}$) and dentin bonding agent (Scotchbond 2$^{(R)}$) under the scanning electron microscope. For this study, eighteen sound extracted human molars were selected. Class I cavities in 12 teeth and class V cavities in 6 teeth were prepared using an air turbine with No. 701 tungsten carbide bur and finished using a low speed handpiece with No. 557 fissure bur. The prepared specimens were then divided into three groups including 4 class I cavities and 2 class V cavities in each group and restored as follows ; Group I. All the prepared cavities were restored with amalgam only (Control). Group II. Two layers of Copalite$^{(R)}$ cavity varnish were applied to the cavities with a gentle stream of air after each application and cavities were restored with amalgam. Group III. The enamel cavity margins were etched with 37% phosphoric acid gel for 60 sec., rinsed for 30 sec. and dried. One layer of visible lightcured Scotchbond Dental Adhesive$^{(R)}$ was applied and immediately cured for 20 seconds with visible light-cure unit and cavities were restored with amalgam. All the specimens were cut at the neck of the teeth and the occlusal halves of specimens were sectioned buccolingually in the longitudinal axis centering the amalgam restorations, using the disk. The cut specimens were ground with sandpapers (400, 600, 800, 1000 grit), and cleaned for 5 minutes in the ultrasonic cleaner (Brason Co. U.S.A.). In the cut surfaces, the amalgam - tooth interfaces were examined under the scanning electron microscope (JSM, 35C type, JEOL). The obtained results were as follows ; 1. The amalgam-tooth interfaces were reduced more significantly in the Copalite$^{(R)}$ and Scotchbond 2$^{(R)}$ application group than in the control group. 2. In the class I cavities, the Scotchbond 2$^{(R)}$ application group showed the findings similar to the Copalite$^{(R)}$ application group in the cavity floor, and the marginal adaptability was better in the side wall than in the cavity floor. 3. In the class I cavities, the Scotchbond 2$^{(R)}$ application group showed better marginal adaptability in the occlusal margin than in the gingival margin. 4. The marginal adaptability was in the order of the Scothbond 2$^{(R)}$ application group, the Copalite$^{(R)}$ application group and the control group.

• 한국터널지하공간학회 논문집
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• 제21권1호
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• pp.93-113
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• 2019

최근 개착식 터널공법으로 널리 사용되고 있는 프리캐스트 라이닝 아치 구조물에 대하여 현장 계측과 수치해석 결과를 비교하여 3힌지 프리캐스트 아치 구조물의 거동을 분석하였다. 현장 계측결과, 천단부에서 가장 큰 연직변위가 측정되었으며 초기에는 상방향으로 변위가 발생하다가 뒤채움 흙이 천단부보다 높아지면서 하방향으로 변위가 발생하였다. 천단부는 최종적으로 원 위치로부터 상방향 19 mm에서 변위가 수렴하였다. 측벽부 최대 수평변위 지점에서의 수평변위는 아치상단까지 뒤채움시 터널 내측으로 발생하여 두 지점간의 수평거리가 줄어들다가, 상부 성토가 진행될수록 수평변위는 감소하여 원래 위치로 이동하였다. 프리캐스트 아치구조물에 대한 변위 분석결과, 지반-구조물의 상호작용을 잘 관찰할 수 있었으며 따라서 기존의 강성구조물과 비교하여 경제적인 설계가 가능할 것으로 기대된다. Duncan 모델을 사용한 유한요소 해석결과를 현장 변위 계측값과 변위 형상 등과 비교하면 유사한 결과를 나타내었다. 수치해석 결과에 의한 측벽부의 수평토압계수는 터널 좌측부는 0.4, 우측부는 0.7에서 수렴하여, 편토압이 발생하는 현장상황 및 현장 변위 계측 결과와도 일치하였다.

• 한국전자파학회논문지
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• 제16권7호
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• pp.690-696
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• 2005

PAPR(Peak to Average Power Ratio)를 줄이는 것은 OFDM(Orthogonal Frequency Division Multiplexing) 통신 시스템에서 매우 중요하다. 본 방법은 Golay상보 부호에 의한 PAPR 감소 기법의 한 가지 방법으로서,부가 신호를 사용하지 않으면서 효과적으로 PAPR을 감소시킬 수 있는 방법이다. 기존의 상보 부호에 의한 PAPR의 감소기법은 오류 정정 부호를 사용하거나 부가 신호를 사용 데이터 전송율이 감소하게 된다 있다. 본 논문에서는 단지 복수위상 상보부호를 이용하여 4-QAM의 성상도를 16-QAM의 형태로 변환하고 부가신호의 추가 및 부호율 증가에 영향을 주지 않는 PAPR감소 기법을 제안한다.

• 대한치과보철학회지
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• 제29권3호
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• pp.55-74
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• 1991

The purpose of this study was to investigate the influence of early functional load around osseointegrated titanium implants. 24 titanium plasma spray coated implants (ITI HS-type) were placed into the previously extracted site in the mandible of six adult dogs. The implants were divided into three groups : the control group was the implants without abutment during the experimental period; the experimental group I was loaded by connecting the contoured abutment after 6 weeks of healing; the experimental group II was loaded after 12 weeks of healing: and the mandibular second premolar and surrounding tissues were selected for natural tooth group to compare the implanted group. All dogs were injected intravenously tetracycline, alizarin red S, and calcein for bone labeling. After the experimental period of 18 weeks, the dogs were sacrificed and longitudinal sections of the bone-implant interface were cut and observed using light microscope, scanning electron microscope, and fluorescence microscope. The results of the study were as follows: 1. Light and scanning electron microscopically, all implant surfaces were well contact with bone tissue at the cortical layer, but some areas of cancellous bone were not contact directly. 2. Fluorescence microscopically, number and size of the new secondary osteons around the implant were increased than those of the natural tooth. 3. Fluorescence microscopically, linear and concentrical fluorescence was observed at or near the surface of all implants, and the bone formation and remodeling of the implants loaded after 6 week of healing were great, and unloaded implants were worst. 4. Fluorescence microscopically, endosteal bone formation was greater than periosteal bone formation at or near the implants. 5. Fluorescence microscopically, number and size of linear and concentric fluorescence was increased at the lingual side than the buccal side of the loaded implants. The result of the study indicate the possibility of the early load to the implant via a prosthesis.

• 반도체디스플레이기술학회지
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• 제8권4호
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• pp.31-36
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• 2009

In this paper, the laser cutting characteristics of the flexible PCB using high power Nd:YAG UV laser were investigated. A specific FPCB model was selected for the experiment. Test sheets were made, which had equal materials and layer structure to those of the outline (OL) region and the contact pad (CP) region in the FPCB. The experiment is made up of two stages. In the first stage of the experiment, the laser cutting fluence was found, which is the threshold fluence to cut the test sheets completely. The laser cutting fluence of the OL sheet is $1781.26{\sim}1970.16\;J/cm^2$ and that of the CP sheet is $2109.34{\sim}2134.34\;J/cm^2$. In the second stage, cutting performance and its qualities were analyzed by the experiment. The laser cutting performance remained almost unchanged for all laser and process parameter sets. The average cutting width (top side/bottom side) of the OL sheet was $40.45\;{\mu}m/11.52\;{\mu}m$ and that of the CP sheet was $22.14\;{\mu}m/10.93\;{\mu}m$. However, the laser cutting qualities were different according to the parameters. The adjacent region of the cutting line on the OL sheet was carbonized as the beam speed was low and the overlap coefficient was high. The surface quality around the cutting line of the CP sheet was about the same. Carbonization and debris occurred on the surface of the cutting line. As a result of the experiment, the cutting qualities were better as the overlap coefficient was made low and beam speed high. Therefore, the overlap coefficient 2 or 3 is proper for the FPCB laser cutting.

• 한국산림과학회지
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• 제17권1호
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• pp.17-22
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• 1973

잣나무 인공단순림(人工單純林)에서 수간(樹幹)의 세장도(細長度)와 편심도(偏心度)를 조사(調査)한바, 우세목(優勢木)의 수간직경(樹幹直徑)과 지상고(地上高)는 대략 평행적 관계이고 지상고(地上高)가 낮은 부위(部位)는 편심(偏心)의 정도(程度)가 $R_1$방향(方向)으로 심하고 수목(樹木)의 심재(心材)는 비대생장(肥大生長)이 심(甚)할수록 크다.

• 융합신호처리학회논문지
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• 제4권1호
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• pp.49-55
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• 2003

현대산업사회의 발전에 따라 신호처리 분야 중 디지털필터의 사용은 급격히 증가하고 있으며, 특히 디지털 영상처리, 디지털 음성처리, CATV 및 각종 통신 분야 등에서 카메라의 Detail processor, Y/C separator, Ghost제거 필터, 표준변환기(NTSC-PAL), Noise reducer 등으로 많이 사용되고 있다. 이러한 디지털필터에는 일반적으로 IIR(infinite impulse response)과 FIR(finite impulse response) 필터가 있으며, 본 논문에서는 구현이 용이하고 선형위상특성을 갖는 FIR 디지털필터를 설계하였다. FIR 디지털필터 설계에 있어서 통과대역의 차단주파수 부근에서 깁스(gibbs) 현상에 의해 생긴 리플을 완화하기 위해 window함수를 사용한다. 그러나, 기존의 window는 고정된 값으로 되어 있으므로 설계목적에 적합한 window함수를 선택함에 있어 다소 문제점이 있다. 따라서, 본 논문에서는 설계목적에 따라 서 융통성있게 선택이 가능한 파라메터를 부가한 변형된 Hanning window를 설계하였으며, 타당성을 입증하기 위해 디지털필터를 설계하여 기존의 Hamming, Hanning, Blackman, Kaiser window와 비교하였으며, 판단기준으로 peak side-lobe와 천이특성 등을 사용하였다.