• Steel and Composite Structures
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• 제23권6호
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• pp.727-736
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• 2017

The application of carbon fiber reinforced polymer (CFRP) in steel structures primarily includes two categories, i.e., the bond-critical application and the contact-critical application. Debonding failure and buckling failure are the main failure modes for these two applications. Conventional electrometric techniques may not provide precise results because of the limitations associated with single-point contact measurements. A nondestructive full-field measurement technique is a valuable alternative to conventional methods. In this study, the digital image correlation (DIC) technique was adopted to investigate the bond behavior and buckling behavior of CFRP-steel composite members. The CFRP-to-steel bonded joint and the CFRP-strengthened square hollow section (SHS) steel column were tested to verify the suitability of the DIC technique. The stereo-DIC technique was utilized to measure continuous deformation. The bond-slip relationship of the CFRP-to-steel interface was derived using the DIC data. Additionally, a multi-camera DIC system consisting of four stereo-DIC subsystems was proposed and applied to the compressive test of CFRP-strengthened SHS steel column. The precise buckling location and CFRP delamination of the CFRP-strengthened SHS steel column were identified. The experimental results confirm that the stereo-DIC technique can provide effective measurements for investigating the behaviors of CFRP-steel composite members.

• 대한조선학회논문집
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• 제55권5호
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• pp.448-455
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• 2018

Glass wool is an eco-friendly materials that is manufactured through a continuous process by processing waste glass. This materials is low cost compared with another materials and has excellent thermal conductivity. For this reason, glass wool is installed as insulation system for LNG carriers and as insulation of building wall as well as various industries. The mechanism of insulation of glass wool is the conduction of the wool itself and convection by space between fibers. Therefore, in order to develop the enhanced thermal conductivity of glass wool is necessary to reduce its own conduction or to insert additional material after manufacturing as well as prevent convection. In this respect, many researchers have been actively studying to decrease thermal conductivity of polyurethane foam using by inserted glass wool or change the chemical component of glass wool. However, many research are aiming reduction of glass wool itself. This study focus on post-processing and inserted different materials; silica-aerogel, kevlar fiber 1mm, 6mm and glass bubble. Experimental results show that the thermal conductivity almost decreases with the addiction of glass bubble and silica aerogel.

• Restorative Dentistry and Endodontics
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• 제25권2호
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• pp.180-192
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• 2000

One bottle system was recently developed in order to simplify the clinical skills and save chair time after continuous improvements on dentin bonding agents. There has been many studies to measure the bond strength of one bottle systems but no actual work has been done on micromorphologic study of resin-dentin interdiffusion zone after one bottle system application. To evaluate the bonding patterns of various commercially available one bottle systems to dentin, observation of resin-dentin interdiffusion zone under TEM was performed. Caries-free human third molars within one month of extractions were chosen for the experiments. The molars were sectioned 1mm above the cementoenamel junction and got rid of the root portions. Crown portions of the teeth were sectioned parallel to occlusal surface so that dentin discs of 1mm in thickness were remained. 7 one bottle systems and 1 two bottle system were applied according to manufacturer's instructions and followings were the results. 1. In every experimental groups, cross bandings of collagen fiber were distinguishable and tight bon dings between the bonding agents and dentin were observed. 2. Hybrid layer was clearly observed in ONE-STEP$^{(R)}$, Prime & Bond$^{(R)}$ 2.1, Syntac$^{(R)}$ SC, MAC-BOND II groups but it was not clear in Single Bond, D-Liner Dual PLUS, ONE COAT BOND groups. 3. Electron-density of hybrid layer was uniform in pattern in MAC-BOND II, Prime & Bond$^{(R)}$ 2.1 groups but not so uniform in ONE-STEP$^{(R)}$ group. 4. Electron-dense amorphous phase in most superior layer of the resin-dentin interdiffusion zone was characteristically observed in Single Bond, Syntac$^{(R)}$ SC, ONE COAT BOND groups. It can be concluded that bondings between the dentin bonding agents and dentin can be various in pattern according to their chemical compositions and the condition during applications.

• 폴리머
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• 제34권4호
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• pp.321-325
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• 2010

피브로인은 실크섬유에서 대량으로 얻어지는 생물고분자이며 수술 봉합사로 장기간 사용되어 생체적합성이 확인되었다. 따라서, 본 연구에서는 생체재료로 사용할 수 있는 피브로인 미립구를 제조하였다. 데칸과 혼합유화제로 이루어진 연속상에 재생 피브로인 액적을 분산시킨 후 건조시켜 형성된 미립구를 회수하여 에탄올 등으로 세척 건조 후 수득하였다. 안정한 유중수형(W/O) 에멀션을 600 rpm으로 교반하는 조건하에서 구형의 피브로인 미립구를 얻 을 수 있었다. 주사전자현미경 사진을 통하여 상압 및 감압하에서 건조된 미립구의 수평균 직경은 각각 21.6 및 8.5 ${\mu}m$로 확인되었다. 토모그래피로 미립구는 내부구조가 채워져 있으나 크기에 따라 중공미립구임을 확인하였고 중탄 산나트륨을 도입하여 중공미립구도 제조하였다.

• Investigative and Clinical Urology
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• 제59권6호
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• pp.392-398
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• 2018

Purpose: To evaluate the initial experience and outcome of photo-selective vaporization of the prostate (PVP) for benign prostatic hyperplasia (BPH) in Pakistan with the use of a 980 nm diode laser. Materials and Methods: A prospective study was performed from November 2016 to December 2017. A total of 100 patients diagnosed with bladder outlet obstruction secondary to BPH who planned for PVP were enrolled in the study. PVP was carried out with a diode laser at 980 nm (Biolitec Diode 180W laser) in a continuous wave with a 600 nm (twister) fiber. Baseline characteristics and perioperative data were compared. Postoperative outcomes were evaluated by International Prostate Symptom Score (IPSS), post void residual (PVR) and maximum urinary flow rate (Qmax) at 3 and 6 months after surgery. Results: The mean age was $65.82{\pm}10.42$, mean prostate size was $67.35{\pm}16.42$, operative time was $55.85{\pm}18.01$ and total energy was $198.68{\pm}49.12kJ$. At 3 months and 6 months, significant improvements were noted (p<0.001) in IPSS $7.04{\pm}1.69$ (-18.92), Qmax $19.22{\pm}4.75mL/s$ (+13.09) and and PVR $18.89{\pm}5.39mL$ (-112.80). Most frequent problems were burning micturition (35%) and terminal dysuria (29%). No significant difference in postoperative hemoglobin was seen in patients who were on anti-platelet drugs. Conclusions: PVP with a diode laser is a safe and effective procedure for the treatment of BPH and is also safe in patients who are on anti-platelet agents.

• 대한의생명과학회지
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• 제27권3호
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• pp.142-153
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• 2021

Liver fibrosis is a wound-healing response to chronic liver injury, which is caused by the continuous and excess deposition of extracellular matrix (ECM). The aim of this study is to investigate whether Uncaria rhynchophylla water extract (UR) can ameliorate thioacetamide (TAA)-induced liver fibrosis. The liver fibrosis model was induced on C57BL/6 mice by intraperitoneal injection with TAA three times a week for 8 weeks. UR (200 mg/kg) or silymarin (50 mg/kg) was administered orally daily for 8 weeks. Biochemical analyses including AST, ALT, MPO, and Ammonia levels were measured in serum. In the mice liver tissues, western blot and histological staining were analyzed. As a result, UR dramatically reduced the levels in serum AST, ALT, MPO, and Ammonia levels. UR treatment regulated NADPH oxidase factors expression, and antioxidant enzymes except for GPx-1/2 were significantly increased via Nrf2 activation. Furthermore, pro-inflammatory mediators, such as COX-2 and iNOS were markedly suppressed through the inhibition of NF-κB activation. Expressions of ECM-related protein including α-SMA and Collagen I were noticeably decreased. The additional histological evaluation confirmed that hepatocyte damage and collagenous fiber accumulation were attenuated. Taken together, these data suggest that UR possessed hepatoprotective effects in TAA-induced liver fibrosis via the NF-κB inactivation and Nrf2 activation. Therefore, UR may act as a potential therapeutic drug against liver fibrosis.

• Composites Research
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• 제35권1호
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• pp.23-30
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• 2022

폴리카보실란은 탄화규소 섬유 방사와 세라믹 제조를 위해 필요한 중요한 전구체이며, 이 전구체는 제조방법 및 공정에 따라 고내열성 및 내산화성 및 연속적인 탄화규소 섬유 생산 능력이 달라진다. 탄화규소 섬유는 폴리카보실란의 합성, 정제 및 분자구조제어기술, 그리고 이를 이용한 용융방사 및 안정화, 열처리 공정을 통해 제조된다. 본 논문에서는 폴리카보실란 전구체를 다양한 용매처리를 통하여 전구체 내에 존재하는 미반응물 및 저분자량의 정제효과를 파악하였으며, 또한 다양한 온도에서의 열처리에 따른 폴리카보실란 전구체의 중합 및 네트워크 재배열에 의한 변화에 대해 열적 분석을 실시하였다. 특히, 폴리카보실란 전구체의 유변물성 특성을 통해 용매처리 및 열처리에 따른 복합점도 및 구조적 배열의 변화를 분석하였다.

• 대한토목학회논문집
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• 제30권2A호
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• pp.161-168
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• 2010

국내 가동 중 일부 원전의 원자로건물에 부착식 텐던이 설치되어 있고, 부착식 텐던에 대한 유효 긴장력 평가는 이들 원전의 계속운전을 위한 주요 현안으로 부각되고 있다. 따라서, 본 연구에서는 System Identification 기법을 이용한 부착식 텐던의 유효 긴장력 평가를 위하여, SI 기법에 유효한 주요 매개변수의 영향 평가를 수행하고 최적의 매개변수를 도출하였다. 본 연구를 위하여, 원자로건물 벽체의 1/5 축소모형 시험체를 제작하였고, 유효 긴장력과 고유진동수 및 변위와의 상관성을 분석하기 위하여 Impact test, SIMO sine sweep test 및 광섬유센서와 변위계에 의한 휨시험을 수행하였다. 시험결과, 고유진동수와 변위 모두 유효 긴장력과 좋은 상관성을 지니는 것으로 나타나, 이들 매개변수 모두 SI 기법의 입력자료로 활용되어 부착식 텐던의 유효 긴장력 예측이 가능한 것으로 분석되었다.

• Clinical Nutrition Research
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• 제11권3호
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• pp.153-158
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• 2022

Critically ill trauma patients generally show good nutritional status upon initial hospitalization. However, they have a high risk of malnutrition due to hyper-metabolism during the acute phase. Hence, suitable nutritional support is essential for the optimal recovery of these patients; therefore, outcomes such as preservation of fat-free mass, maintenance of immune functions, reduction in infectious complications, and prevention of malnutrition can be expected. In this report, we present the experience of a patient subjected to 40 days of nutritional interventions during postoperative intensive care unit (ICU) care. Although the patient was no malnutrition at ICU admission, enteral nutrition (EN) was delayed for > 2 weeks because of several postoperative complications. Subsequently, while receiving parenteral nutrition (PN), the patient displayed persistent hypertriglyceridemia. As a result, his prescription of PN were converted to lipid-free PN. On postoperative day (POD) #19, the patient underwent jejunostomy and started standard EN. A week later, the patient was switched to a high-protein, immune-modulating formula for postoperative wound recovery. Thereafter, PN was stopped, while EN was increased. In addition, because of defecation issues, a fiber-containing formula was administered with previous formula alternately. Despite continuous nutritional intervention, the patient experienced a significant weight loss and muscle mass depletion and was diagnosed with severe malnutrition upon discharge from the ICU. To conclude, this case report highlights the importance of nutrition interventions in critically ill trauma patients with an increased risk of malnutrition, indicating the need to promptly secure an appropriate route of feeding access for active nutritional support of patients in the ICU.

• 한국환경농학회지
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• 제32권4호
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• pp.323-331
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• 2013

국내 조사료의 안정적인 생산을 위하여 답리작에서 돈분액비를 이용하여 동 하계에 사료작물을 재배하고 생육 및 사료가치 그리고 토양에 미치는 영향을 조사하였다. 파종 15일 후 동계작물과 하계 사료용 옥수수 모두 돈분액비 처리구가 화학비료구에 비하여 2.6~3배의 높은 출현율을 보였고 시험작물 모두 초장이 액비시용구에서 약 2배 이상 증가하였으나 생육이 진행됨에 따라 그 차이는 낮아졌다. 동계작물의 수량은 돈분액비 2년 연용시 2년차에서 도복으로 인하여 건물중이 화학비료구가 약간 높은 결과를 보였다. 하계 사료용 옥수수의 경우에도 돈분액비 처리구가 초장, 엽수, 직경 등이 화학비료구에 비하여 9~11%정도 높았으나 동계작물과 마찬가지로 액비연용 2년차에 도복에 의한 피해로 건물중이 3~9%나 화학비료구가 높았다. 사료가치는 동계 사료작물의 경우 조단백질 함량은 액비처리구와 화학비료구간에 유사하였고 IRG가 15.7%로 가장 높았으며 NDF와 ADF는 동계작물은 비종차이에 의한 차이는 크게 나타나지 않았으나 하계작물의 경우는 액비처리구의 ADF가 낮은 경향이었다. TDN은 액비처리구 IRG와 청보리가 가장 높았다. 사료용 옥수수는 액비처리와 화학비료 처리구와 거의 대등한 결과를 나타냈다. 시험전후 토양 비교 결과 가축분뇨 액비처리를 하였을 때 EC, 유기물, 유효인산 및 치환성 양이온의 함량이 증가하였고 특히 인산과 나트륨의 함량이 증가하였다. 이상의 결과로 답리작에서 동 하계 사료작물 재배시 토양 검정에 의해 가축분뇨 액비를 시용한다면 화학비료와 대등한 수량 및 사료가치를 보여 재배단가를 낮추고 국내 조사료 안정생산에 도움을 줄 것으로 생각된다.