• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.11a
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• pp.43-43
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• 2001

원료의 저급화와 공정의 폐쇄화가 급속히 진행되고 있는 현재의 국내 제지산업 현황을 고려할 때 고품질의 제품을 저렴하게 생산하기 위해서는 화학첨가제의 효과적 활용기술 확립과 이를 통한 초지공정 wet end의 성공적 제어기술이 요청된다. 특히 환경보전과 환 경관련 규제에 부응하기 위하여 초지공정의 무방류화가 점차 가속화되고 있는 현 시점에 서 wet end의 효율적 관리를 위해서는 그 동안 개방형 wet end에서 적용되던 개념의 공 정관리의 한계를 극복할 수 있는 기술 개발이 필요하다. 공정의 폐쇄화에 따른 습부화학적 문제를 해결하기 위해서는 백수의 재활용에 따른 지료 화학적 특성을 평가하고 고분자전해질의 거동을 분석해야 한다. 보류향상제 혹은 탈수촉 진제로서 첨가된 고분자전해질은 그 기능을 수행하기 위해서는 섬유에 흡착이 이루어져 야 하므로 백수로 제조된 지료 내에서 고분자전해질의 흡착 특성을 파악하는 것은 습부에 서 일어나는 현상들에 대한 이해 및 효율적인 공정제어를 위한 첫 단계라 할 수 있다. 본 연구에서는 실험실적으로 제조된 백수를 이용하여 조성된 지료 내에서 양이온성 구 아 검의 흡착현상을 분석하였다. 본 연구에서는 폐쇄화의 기준으로 폐쇄화 정도(Level of C Closure ; LC)에 따라 실험을 수행하였다. 여기에서 LC란 총 사용된 물의 양에 대한 지료조성 시 사용되는 백수의 양을 백분율로 나타낸 것이다. 양이온성 구아 검의 흡착을 평가하기 위해 PhenoVsulfuric acid spectrophotometric method를 이용하여 펄프 슬 러리 상등액에 존재하는 미흡착된 양이온성 구아 검의 함량을 측정하였고. 양이온성 구아 검 이 섬유상에 흡착하였을 때 나타나는 섬유의 S-potential 변화와 펄프 상등액의 양이 온 요구량 변화를 평가하였으며 이들의 상관관계를 분석하였다.축력으로 변형시키는데 비해 도침은 단순히 압축 압력만을 종이에 가하는 것이 다르다고 볼 수 있는데, 라 이너지와 백상지가 같은 조건하에서 왜 이러한 큰 차이를 보이는 이유를 아직 알수 없다.해 동일한 공정 데이터들올 이용하여 보편적으로 사용하는 통계기법 중의 하나인 주성분회귀분석을 실시하였다. 주성분 분석은 여러 개의 반응변수에 대하여 얻어진 다변량 자료의 다차원적인 변 수들을 축소, 요약하는 차원의 단순화와 더불어 서로 상관되어있는 반응변수들 상호간 의 복잡한 구조를 분석하는 기법이다. 본 발표에서는 공정 자료를 활용하여 인공신경망 과 주성분분석을 통해 공정 트러블의 발생에 영향 하는 인자들을 보다 현실적으로 추 정하고, 그 대책을 모색함으로써 이를 최소화할 수 있는 방안을 소개하고자 한다.금 빛 용사 둥과 같은 표면처리를 할 경우임의 소재 표면에 도금 및 용 사에 용이한 재료를 오버레이용접시킨 후 표면처리를 함으로써 보다 고품질의 표면층을 얻기위한 시도가 이루어지고 있다. 따라서 국내, 외의 오버레이 용접기술의 적용현황 및 대표적인 적용사례, 오버레이 용접기술 및 용접재료의 개발현황 둥을 중심으로 살펴봄으로서 아직 국내에서는 널리 알려지지 않은 본 기 술의 활용을 넓이고자 한다. within minimum time from beginning of the shutdown.및 12.36%, $101{\sim}200$일의 경우 12.78% 및 12.44%, 201일 이상의 경우 13.17% 및 11.30%로 201일 이상의 유기의 경우에만 대조구와 삭제 구간에 유의적인(p<0.05) 차이를 나타내었다.는 담수(淡水)에서 10%o의 해수(海水)로 이주된지 14일(日) 이후에 신장(腎臟)에서 수축된 것으로 나타났다. 30%o의 해수(海水)에 적응(適應)된 틸라피아의 평균 신사구체(腎絲球體)의 면적은 담수

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.2
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• pp.108-118
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• 2010

Introduction: Maxillary posterior region, compared to the mandible or maxillary anterior region, has a thin cortical bone layer and is largely composed of cancellous bone, and therefore, it is often difficult to achieve primary stability. In such cases, sinus elevation with bone graft is necessary. Materials and Methods: In this research, 121 patients who had implant placement after bone graft were subjected to a follow-up study of 5 years from the moment of the initial surgery. The total survival rate, 5-year cumulative survival rate and the influence of the following factors on implant survival were evaluated; the condition of the patient (sex, age, general body condition), the site of implant placement, diameter and length of the implant, sinus elevation technique, closure method for osseous window, type of prosthesis and opposing teeth. Results: 1. The 5-year cumulative survival rate of total implants was 90.5%, there was no significant difference between sex, age, the site of implant placement, diameter and length of the implant, sinus elevation technique, and the type of opposing teeth. 2. Patients with diabetes mellitus < osteoporosis and smooth-surfaced machined group < hydroxyapatite (HA)-treated group and homogenous demineralized freeze dried allogenic bone (DFDB) bone graft only group had significantly lower survival rate. 3. With less than 4 mm of residual alveolar ridge height, lateral approach without closing the osseous window resulted in a significantly lower survival rate. 4. Restoration of a single implant showed a significantly lower survival rate, compared to cases where the superstructure was joined with several implants in the area. Conclusion: Patients with diabetes or osteoporosis need longer period of time for osseointegration compared to the normal, and the dentists must be prudent when choosing a surface treatment type and the bone graft material. Also, as the vertical dimension of the residual alveolar ridge can influence the result, staged implant placement should be considered when it seems difficult for the implant to gain primary stability from the residual bone with less than 4 mm of vertical dimension. It is recommended to obdurate the bone window and that the superstructure be connected with several impants in the peripheral area.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.79-85
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• 2016

A concrete silo plays an important role in subsurface low- and intermediate-level waste facilities (LILW) by limiting the release of radionuclides from the silo geosphere. However, due to several physical and chemical processes the performance of the concrete structure decreases over time and consequently the concrete loses its effectiveness as a barrier against groundwater inflow and the release of radionuclides. Although a number of processes are responsible for degradation of the silo concrete, it is determined that the main cause is corrosion of the reinforcing steel. Therefore, the time it takes for the silo concrete to fail is calculated based on two factors: the initiation time of corrosion, defined as the time it takes for chloride ions to penetrate through the concrete cover, and the propagation time of corrosion. This paper aims to estimate the time taken for concrete to fail in a LILW disposal facility. Based on the United States Department of Energy (DOE) approach, which indicates that concrete fails completely once 50% of the volume of the reinforcing steel corrodes, the corrosion propagation time is calculated to be 640 years, which is the time it takes for corrosion to penetrate 0.640 cm into the reinforcing steel. In addition to the corrosion propagation time, a diffusion equation is used to calculate the initiation time of corrosion, yielding a time of 1284 years, which post-dates the closure time of the LILW disposal facility if we also consider the 640 years of corrosion propagation. The electrochemical conditions of the passive rebar surface were modified using an acceleration method. This is a useful approach because it can reduce the test time significantly by accelerating the transport of chlorides. Using instrumental analysis, the physicochemical properties of corrosion products were determined, thereby confirming that corrosion occurred, although we did not observe significant cracks in, or expansion of, the concrete. These results are consistent with those of Smartet al., 2006 who reported that corrosion products are easily compressed, meaning that cracks cannot be discerned by eye. Therefore, it is worth noting that rebar corrosion does not strongly influence the hydraulic conductivity of the concrete.

• Archives of Reconstructive Microsurgery
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• v.8 no.1
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• pp.35-43
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• 1999

There are lots of reconstructive ways like direct closure, skin graft, local flap, regional flap, distant flap, free flap and so on. Microsurgical reconstruction is regarded as the last step in various reconstructive methods. So the failure of this last step causes the troublesome situation for both of patients and surgeon. The purpose of this paper is to investigate the problems in failed free flap surgery and to introduce the strategy of appropriate management in wound of free flap failure. We performed 252 cases of free flap surgeries from May, 1988 to June, 1998. Among these cases, we failed 9 cases of free flaps. Patients' age ranged from 19 to 63. There were 7 males and 2 females. Site of failure were 3 head and neck areas, 2 hands, and 4 lower extremities. However there was no failure in breast, trunk, buttock, and genitalia. 7 patients who had region of head and neck, and lower extremity underwent the second free flap surgery successfully in postoperative 4 to 16 days following debridement of necrotic tissue. However 2 patients who had region in hand were managed with conventional treatment like skin graft and distant flap. Vein grafts were needed in 3 cases of 7 second free flaps, and 1 patients needed sequentially-linked free flaps with two flaps. The second free flaps were inevitable for head and neck area because the large complex wound may cause the lifethreatening condition without immediate coverage with well vascularized flap. Lower extremity also needed second free flap for limb salvage. Hand could be managed with conventional method, even though healing time was quite delayed. We thought second free flap surgery in free flap failure cases should be performed with more careful preoperative evaluation and refined surgery. Success of second free flap surgery could recover the very difficult situation due to previously failed operation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.3
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• pp.199-207
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• 2013

In hydrographic survey, data surveyed with multibeam system includes various errors due to multiple factors. These are corrected by a calibration called patch test, and if existing method is used, the test needs to be conducted for about 8 times for precise system calibration. For more prompt and precise multibeam system calibration, the exact offset of a ship was determined using terrestrial laser scanning and TS surveying, which was used as the initial input for the patch test. In the result, the error of closure was 0.001 m or less for TS surveying and backsight error was 0.005 m or less for scanning. All the surveying data based on the same local coordinate was converted into vessel reference coordinate during which R-square for all rotation angles was 0.99 or higher and standard deviation was 0.008 m or less. Finally, in a patch test using calculated offset of sensors and motion sensor offset, the offset of MBES transducer satisfied manual on hydrography only with 1-time calibration. With these results, it is thought that terrestrial laser scanning and TS surveying can fully be utilized for multibeam system calibration.

• Archives of Plastic Surgery
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• v.37 no.5
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• pp.589-594
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• 2010

Purpose: Full thickness skin grafts are useful in the reconstruction of facial skin defects when primary closure is not feasible. Although the supraclavicular area has been considered as the choice of donor site for large facial skin defect, many patients are reluctant to get a neck scar and some patients do not have enough skin to cover the defect owing to the same insult occurred to the neck such as burn accident. We present several cases of reconstruction of facial skin defects by freehand full-thickness skin graft from anterolateral chest wall resulting aesthetically acceptable outcome with lesser donor site morbidity. Methods: Retrospective review was performed from March, 2007 to September, 2009. 15 patients were treated by this method. Mean age was 31.5 years. The ethiology was congenital melanocytic nevus in 7 cases, capillary malformation in 5 cases and burn scar contracture in 3 cases. Mean area of lesion was measured to 67.3 cm2 preoperatively. The lesion was removed beneath the subcutaneous fatty tissue layer. The graft was not trimmed to be thin except defatting procedure. For the larger size of defect, two pieces of grafts were harvested from both anterolateral chest wall in separation and combined by suture. Results: The mean follow up period was 9.7 months. All the grafts survived without any problem except small necrotic areas in 4 cases, which healed spontaneously under conventional dressings in 6 weeks postoperatively. Color match was relatively excellent. There were 2 cases of hyperpigmentation immediately, but all of them disappeared in a few months. Conclusion: In cases of large facial skin defects, the anterolateral chest wall may be a good alternative choice of full-thickness skin graft.

• Journal of Chest Surgery
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• v.32 no.5
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• pp.438-441
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• 1999

Background: Minimally invasive cardiac surgery has emerged as a new approach to the conventional median sternotomy. The suggested advantages of the minimally invasive technique includes improved cosmesis, simplicity of opening and closing the chest, less postoperative pain, less risk of infection and bleeding, early rehabilitation, and reduced length of hospital stay. Material and Method: Between March 1997 and December 1997, we performed 36 cases of minimally invasive cardiac surgery via three different approaches ; right paramedian, transverse sternotomy and mini-sternotomy with upper sternal split. Result: There was no operative mortality. Postoperative complications were atrial fibrillation in 4 patients, bleeding that required reoperation in 1 patient, and delayed wound closure in 1 patient who underwent 3rd redo operation. Average length of skin incision was 9.1${\pm}$0.9 cm. Average duration of stay in the intensive care unit was 48${\pm}$29 hours and the patients were discharged 10${\pm}$7 days after the operation. Conclusion: In spite of the difficulties in defibrillation, deairing, and cardiac decompensation, minimally invasive approaches will be applied increasingly because of the suggested advantages.

• Journal of Chest Surgery
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• v.35 no.8
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• pp.580-583
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• 2002

Background: Obtaining precise hemodynamic and morphological information in the early postoperative period after surgical correction of congenital heart disease is important in determining the need for future medical or surgical intervention. We investigated the residual shunting after surgical repair of simple ventricular septal defect in order to know the incidence of residual shunting in the postoperative period and the natural history of small residual shunts located in the peripatch area. Material and Method: Forty three consecutive patients under one year of age who underwent patch repair of a simple ventricular septal defect were evaluated for incidence of residual shunts by echocardiography. Result: Eleven patients had echocardiographic residual shunt in the peripatch area at immediate postoperative period, however, there were no patients who needed reoperation due to deteriorated hemodynamic effect of residual shunt. The incidence of residual shunts was not significantly different with type of ventricular septal defect and material used for closure. During follow up period, two patients were lost and remaining nine patients no longer showed evidence of residual shunt. The mean time of last evidence of shunt was $4.2{\pm}3.6$ months after operation. Conclusion: Residual peripatch shunt flow was frequently noted in the immediate postoperative period following surgical repair of ventricular septal defect, however, most of them were disappeared within six months.

• The Korean Journal of Pain
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• v.12 no.2
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• pp.205-210
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• 1999

Background: Epidural morphine for postoperative pain control has a serious risk of respiratory depression and other side effects such as pruritus, nausea and urinary retention. In recent years, it is known that epidural administration of ketamine potentiates the effect of epidural morphine, and so decrease the side effects of epidural morphine. This study was performed to evaluate the analgesic efficacy of epidurally administered ketamine and whether this epidural administration can decrease the amount of epidural morphine. Methods: Sixty patients scheduled for the elective cesarean section were randomly selected. All patients were given subarachnoid injection of tetracaine 9 mg. Group I received epidural bolus injection of 0.15% bupivacaine 10 ml with morphine 2 mg followed by a continuous infusion of 0.125% bupivacaine 100 ml containing morphine 4 mg after peritoneum closure, and group II received the same method as group I except for the addition of epidural ketamine 30 mg. Analgesic effects were assessed using Numeric Rating Score (NRS) and Prince Henry Score (PHS). Also, the degree of satisfaction and the incidence of the side effects were observed. Results: Analgesic effects were significant in both groups after drug administration. But NRS and PHS were not significantly different between two groups at all times. The incidence of nausea and vomiting was 11 out of 30 in group I and 9 out of 30 in group II and the incidence of itching was 11 out of 30 in group I and 8 out of 30 in group II. Number of patients using additional analgesics were 2 and 1 in group I and II, respectively. Conclusions: Epidural ketamine did not potentiate the analgesic effect of epidural morphine and could not decrease the side effect of epidural morphine.

• Journal of the Korean Arthroscopy Society
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• v.3 no.2
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• pp.127-131
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• 1999

Avulsion fractures of the intercondylar eminence of the tibia are not uncommon. In the displaced avulsion fracture, anatomical reduction and firm fixation of fracture fragments are needed but the most of the conventional operative techniques including arthroscopic technique are relatively complex and need. The results were not always satisfactory due to the risk of postoperative complications such as wound infection, premature epiphyseal closure and loss of fixation after early motion etc. So we describe a simple and safe modified method of arthroscopic reduction and fixation for avulsion fractures of the intercondylar eminence of the tibia. In our thirteen cases, we achieved anatomical reduction and secure fixation using cannulated screw through the three arthroscopic portals (anterolateral, medial mid-patellar and central). Postoperatively, immediate limited range of motion of the knee and partial weight bearing were possible. Additional use of the washer afforded safe fixation of comminuted avulsion fracture. The advantage of this technique includes its technical simplicity, easy removal of hardware, ability to treat comminuted type IV fracture with washer, no additional skin incision, no damage to growing plate in growth children and less morbidity.