• Clean Technology
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• v.29 no.3
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• pp.200-216
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• 2023

Ginkgo leaves are considered waste biomass and can cause problems due to the strong insecticidal actions of ginkgolide A, B, C, and J and bilobalide. However, Ginkgo leaf biomass has high organic matter content that can be converted into fuels and chemicals if suitable technologies can be developed. In this study, the effect of pyrolysis temperature, minimum fluidized velocity, and Ginkgo leaf size on product yields and product properties were systematically analyzed. Fast pyrolysis was conducted in a bubbling fluidized bed reactor at 400 to 550℃ using silica sand as a bed material. The yield of pyrolysis liquids ranged from 33.66 to 40.01 wt%. The CO₂ and CO contents were relatively high compared to light hydrocarbon gases because of decarboxylation and decarbonylation during pyrolysis. The CO content increased with the pyrolysis temperature while the CO₂ content decreased. When the experiment was conducted at 450℃ with a 3.0×U_mf fluidized velocity and a 0.43 to 0.71 mm particle size, the yield was 40.01 wt% and there was a heating value of 30.17 MJ/kg, respectively. The production of various phenol compounds and benzene derivatives in the bio-oil, which contains the high value products, was identified using GC-MS. This study demonstrated that fast pyrolysis is very robust and can be used for converting Ginkgo leaves into fuels and thus has the potential of becoming a method for waste recycling.

• Journal of Chest Surgery
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• v.30 no.12
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• pp.1225-1231
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• 1997

Spontaneous pneumothorax is the sudden collapse of a lung usually caused by air leakage from a subvisceral pleural blob. Responses to closed thoracostomy,thoracentesls and simple observation are usually prompt and effective. But in some cases, these are unsucceful and open thoracotomy is indicated. A clinical evaluation was performed on 242 cases(236 patients) of open thoracotomy in spontaneous pneumoth rax who were admitted and treated at department of Thoracic and Cardiovascular Surgery. Masan Samsung General Hospital during the past 9 years from January 1988 to December 1996. The results were as follows 1. The sex ratio was male predominance(M:F=11.7:1) 2. The most common age group were 2nd, 3rd decades(2nd=29.3%, 3rd=30.2%). 3. The most common chief complaints were chest pain and dyspnea(chest pain=41.7%. dryspnea= 36.8). 4. The etiologic factors of spontaneous pneumothorax were primary spontaneous pneumothorax(86.4%), tuberculosis(9.1%), COPD(3.7%) and pleuritis(0.8%). 5. The site of spontaneous pneumothorax was 52.1% in right, 45.4% in left and 2.5% in both. 6. The common indications of open thoracotomy were recurrence(44.2%), persistent air leakage(31.8%) and inadequate expansion(15.7%). 7. The operative procedures were bullectomy or mechanical pleurodesis through posterolateral thoracotomy or median sternotomy. 8. The most frequent location of bulla or blob were apical segme t oi RUL(35.1%) and apicoposterior segment of LUL(41.3 %). 9. The number of bulla or blob were mainly 1 to 5(88%), and there were no significant differences among operation indications. 10. The size of bulla or bleb were mainly below 5cm(81%)and small bulla($\leq$1cm) were predominant in recurrence group but large bulla(>5cm)were predominant in persistent air leakage and inadequate expansion group. 11. The pleural adhesion was seen in 54.5%.(Recurrence group 64.1%,Persistent air leakage group 51.9%,Inadequate expansion group 47.4%).

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.235-241
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• 2004

The dissolved air flotation (DAF) process has been widely used for removing suspended solids with low density in water. It has been known as measuring the size of microbubbles precisely which move upward rapidly in contact zone is difficult. In this study particle counter monitoring (PCM) method is used to measure the rising microbubble after injection from a nozzle. Size and distribution curve of microbubbles are evaluated at different conditions such as pressure drop at intermediate valve, length of pipeline between saturation tank and nozzle and low pressure. And the efficiency is also checked when it collides with different size floc. The experimental results show the following fact. As the final pressure drop occurred closer to a nozzle, the bubble size became smaller. And small bubble collides with large floc as well as small one because of its physical characteristic. However large bubble collides well with large floc rather than small one since hydrodynamic flow in streamline interferes to collide between two. With performing computational process by mathematical model we have analyzed and verified the size effect between bubble and floc. Collision efficiency is the highest when P/B ratio shows in the range of 0.75 < P/B ratio ($R_{particle/Rbubble}$) < 2.0.

• Journal of Chest Surgery
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• v.34 no.5
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• pp.393-398
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• 2001

배경: 일차성 자연기흉의 재발방지를 위해서 폐기포절부위에 흡수성 셀룰로스망사와 Fibrin gluefm 도포하여 수술후 재발율을 줄일 수 있는 지 알아보았다. 대상 및 방법: 1996.4우러부터 2000.6월까지 2명의 술자가 222례의 일차성 자연기흉을 수술하였으며, 수술시기와 치료방법에 따라 4군으로 나누어 비교하였다. 제1군은 1996년부터 1997년가지 비디오흉강경수술 및 기계적 늑막유착술로 시술받은 군(25례), 제 2군은 같은 기간동안 액와개흉술 및 늑막유착술로 시술받은 군(53례), 제 3군은 1998년부터 2000.4월까지 흉강경수술 및 늑만유착술로시술받은 군(110례), 제 4군은 1999.7월부터 2000.6월까지 흉강경수술 및 봉합부위를 셀룰로스망사와 Fibrin glue로 보강한 군(34례)이었다. 각 군간, 엑스선상 기흉의 크기 및 폐기포의 수나 크기에 따라 재발율, 공기누출시간 및 흉관지속지간등을 일반선형모델을 사용하여 비교 분석하였다. 결과: 대상환자는 남자 203례, 여자 19례 이었고, 나이는 14게에서 68세이었고, 평균연령은 23.2$\pm$9.6세였다. 재발한 경우는제 1군이 5례(25%), 제 2군이 2례(3.8%), 제 3군이 5례(4.5%)이었고, 제 4군은 재발례가 없었다. 재발례는 모두 수술자의 수술경험이 2년이내일 때 발생하였다. 흉관지속기간은 제 4군이 제 3군(p<0.0006) 및 제1, 제2군(p<0.0001)에 비해서 더 짧았고, 술후 공기누출이 제 4군에서는 없었다. 술전흉부엑스선상 기흉의 크기에 따른 수술후 기흉의 재발울은 경도의 기흉에서 14.3%(2/14)이었고, 중등도 기흉에서 7.4%(10/134)이었으며, 심한 기흉에서는 재발례가 없었다. 재수술한 12례중 봉합부위근처에서 기포가 발행된 경우가 9례(75%)로 많았다. 결론: 재발방지를 위한 시술로 늑막유착술을 시행하지 않고 폐기포절제부위를 흡수성 셀룰로스망사와 Fibrin glue로 덮어주는 시술은 비교적 용이하며, 수술 후 공기 누출이 없었고, 수술 후 흉관지속기간이 더 짧았고, 단기간 추적에서 재발이 없었다. 재발에 영향을 미치는 것으로 흉부엑스선상 기흉의 크기가 작은 경우에는 재발율이 더 높았고, 수술자의 경험이 중요하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.5
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• pp.369-377
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• 1999

Recently, it is gradually raised necessity that thickness of thin film is measured accuracy and managed in industrial circles and medical world. Ultrasonic signal processing method is likely to become a very powerful method for NDE method of detection of microdefects and thickness measurement of thin film below the limit of ultrasonic distance resolution in the opaque materials, provides useful information that cannot be obtained by a conventional measuring system. In the present research. considering a thin film below the limit of ultrasonic distance resolution sandwiched between three substances as acoustical analysis model, demonstrated the usefulness of ultrasonic signal processing technique using information of ultrasonic frequency for NDE of measurements of thin film thickness. Accordingly, for the detection of delamination between the junction condition of boundary microdefect of thin film sandwiched between three substances the results from digital image processing.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.209-217
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• 2011

In recent days, while taller and more massive structures such as huge bridges and super skyscrapers have been welcomed, the structural stabilization in design and construction have been gradually limited due to the major weakness of current concrete which is relatively heavier when compared with its strength. To improve the weakness of the current concrete, The lightweight concrete with light weight and high strength should be used; however, not many researchers in Korea have studied on the lightweight concrete. Generally, artificial lightweight aggregate produced through high-temperature-plasticization has a possibility of its body-expansion with many bubbles. Therefore, depending on the size of aggregate, the effects of bubbles on the specific weight and strength of the lightweight concrete should be studied. In this study, considering grain-size, the mix design of the artificial lightweight aggregate produced through the high-temperature-plasticization and the body-expansion of waste and clay from the fire power plant in Korea was conducted. The experiment to analyze the variation in specific weight and strength of the lightweight concrete was followed. From these experiments, the optimized grain-size ratio of the artificial lightweight aggregate for the enhancement of high-strength from the lightweight concrete was revealed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.85-91
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• 2011

This study aims at evaluating feasibility of Bottom ash-mixed Foam Cement Banking(BFCB) Method on the enhancement of soft soil, which is developed to reduce self-weight of banking by applying bottom ash and foam. to cement slurry. In order to measure the behavior of soil when BFCB layer was covered to soft ground, a testing equipment for mock-up test was fabricated and phased loads were applied up to measurement of yielding and ultimate strengths as well as movement of ground particles. In addition, these measured values such as settlement and heaving were compared with ones of surface-hardening method prevailing on soil improvement. As the result through mock-up test, BFCB showed lower values of ground deformation, while wider range of deformation was observed in compare to the other method. And settlement and heaving were measured lower, which implies the method developed is very effective to applicability of soft ground.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.90-90
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• 2000

이온빔을 이용한 리소그래피의 경우 미크론 이하의 미세구조를 형성할 수 있는 유용한 수단으로서 방사광 X-선과 함께 주목을 받고 있으며, 이와 같은 미세구조 제작은 MEMS (Micro Electro-Mechanical System) 개발에 있어서 매우 중요하다. 그러나 이온빔을 이용한 리소그래피에 대한 연구가 많이 이루어져 있지 않은 상태이다. MeV급 양정사 빔을 이용한 리소그래피의 가능성을 확인하기 위하여 기본적인 실험을 수행하였으며, 최적 이온빔 조사 조건 및 최적 현상 조건을 도출하였다. Resist로는 PMMA를 사용하였으며, 1.8 MeV 양성자 빔을 사용하여 50$\mu\textrm{m}$ 깊이의 구조물을 만들었다. 1.8MeV 양성자 빔의 조사선량이 7x1013ions/cm2 이상이 되면 PMMA 내부에 기포가 형성되므로 적정 조사선량을 4x1013 ions/cm2으로 결정하였다. 또한 선량을 4x1013ions/cm2 으로 고정하고 선량률을 변화시켜주면 선량률이 8x1011ions/cm2S 일 때부터 시료에 기포나 터짐 현상 등의 문제가 발생하였으며 5x1010~~1x1010ions/cm2s 의 선량률이 조사시간, 결함측면에서 가장 적합한 영역임을 알 수 있었다. 현상제로는 20% morpholine, 5% etanolamine 60% diethylenglykol-monobutylether, 15% 증류수를 혼합하여 사용하였다. 현상 온도를 30~5$0^{\circ}C$로 변화시켜서 현상을 한 결과, 4$0^{\circ}C$에서 현상 소요시간은 1시간 이내이며 SEM으로 관찰된 표면의 상태도 제일 양호한 결과를 보였다. 82 mesh 밀도, 선굵기 60$\mu\textrm{m}$, 크기 20x20 mm인 백금 망을 마스크로 사용하여 실제 3차원 미세구조를 제작하여 보았다. 그림 1에서 제작된 구조물의 SEM 사진을 보여주었으며, 식각된 면의 조도가 매우 뛰어나며 모서리의 직각성도 우수함을 확인할 수 있다. 이와 같이 도출된 시험 조건을 기초로 하여 리소그래피 후에 전기 도금을 이용한 금속 몰드 제작 및 이온빔 리소그래피 장점을 최대한 살릴수 있는 미세구조 제작에 대한 연구를 계속 추진할 계획이다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.6
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• pp.726-733
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• 2004

The growth of the critical size bubble by diffusion process in viscoelastic medium was treated by an integral method for the concentration boundary layer adjacent to the bubble wall. In this study, we obtained a set of the first order time dependent equations to obtain bubble radius and gas pressure inside the bubble simultaneously. The calculated final cell sizes depending on the initial saturation pressure are in close agreement with the observed ones. The governing equations developed in this study may be used in polymer processing of microcellular foams.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.628-630
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• 2002

본 논문은 이상 유동장 시스템의 전기 단층촬영 기법의 성능을 향상시키기 위해 Matlab과 같은 계산 도구에 데이터 통신 기능을 추가적으로 구현하여 노드들의 협력 계산을 지원한다. 구현된 통신 기능은 Matlab 명령어 라인이나 m-file에서 직접 호출할 수 있는 동적 링크 라이브러리 형태로 제공되며 호출시 전달된 Matlab 고유 방식으로 표현된 행렬을 Windows 운영체제에서 제공하는 파이프 기능을 이용하여 네트워크를 통해 수신자에게 전달한다. O(n$^3$)의 복잡도를 갖는 다수의 연산으로 구성된 영상 복원 알고리즘에 있어서 사전 분석과정을 협력 계산함으로써 물체 내부의 상황에 따라 n의 크기를 감소시켜 알고리즘의 수행속도를 크게 개선할 수 있다. 본 논문에서 구현된 협력 계산 환경과 프로그램은 주어진 물체내부 기포 분포에 대해 동적 칼만 필터 프로그램을 8개의 노드를 사용하였을 때 15배까지 수행속도를 향상시켰다. 따라서 고가의 병렬 시스템 대신 현재 이용이 가능한 저비용의 클러스터 계산 환경을 ET 기법에 적용하여 보다 정확하고 신속한 영상 복원을 수행할 수 있다.