• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.461-468
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• 2009

Magnetic resonance electrical impedance tomography (MREIT) enables us to perform high-resolution conductivity imaging of an electrically conducting object. Injecting low-frequency current through a pair of surface electrodes, we measure an induced magnetic flux density using an MRI scanner and this requires a sophisticated MR phase imaging method. Applying a conductivity image reconstruction algorithm to measured magnetic flux density data subject to multiple injection currents, we can produce multi-slice cross-sectional conductivity images. When there exists a local region of fat, the well-known chemical shift phenomenon produces misalignments of pixels in MR images. This may result in artifacts in magnetic flux density image and consequently in conductivity image. In this paper, we investigate chemical shift artifact correction in MREIT based on the well-known three-point Dixon technique. The major difference is in the fact that we must focus on the phase image in MREIT. Using three Dixon data sets, we explain how to calculate a magnetic flux density image without chemical shift artifact. We test the correction method through imaging experiments of a cheese phantom and postmortem canine head. Experimental results clearly show that the method effectively eliminates artifacts related with the chemical shift phenomenon in a reconstructed conductivity image.

• 비파괴검사학회지
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• 제34권1호
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• pp.60-67
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• 2014

본 연구에서는 사장교의 핵심부재인 케이블 점검을 위한 자동화 검사 시스템을 개발하였다. 강자성체로 이뤄진 연속체 구조물인 케이블의 내외부 검사에 적합한 비파괴검사법으로는 선행연구를 통해 검증된 누설자속탐상법이 적용되었고, 홀센서와 영구자석을 이용하여 다채널의 누설자속 측정용 자기센서헤드를 제작하였다. 또한 케이블 검사의 자동화로 접근성을 높이기 위해 사장교 케이블을 따라 이동할 수 있는 바퀴굴림 방식의 케이블 등반 로봇을 설계 및 제작하였고, 로봇을 다양한 디바이스에서 모니터링 및 제어하기 위한 컨트롤 프로그램을 제작하였다. WLAN 방식의 무선통신기술을 적용하여 원격으로 계측 데이터 전송 및 로봇제어를 가능하게 하였다. 최종적으로 본 연구를 통해 개발된 세부 기술들이 연동된 누설자속탐상법 기반 케이블 이동형 진단 시스템을 이용하여 실제 운용중인 서해대교의 케이블을 대상으로 현장 시험을 수행함으로써 본 시스템의 현장 적용성을 검증해보았다.

• 한국항공우주학회지
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• 제33권9호
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• pp.104-112
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• 2005

본 논문은 항공전자시스템 통제와 항법 및 사격통제를 통합하고 비행, 항법 및 무장조준 임무를 위한 정보를 제공하는 항공전자시스템컴퓨터(ASC)의 탑재소프트웨어(OFP) 개발 기법을 제안한다. OFP 개발을 위해 중앙처리장치 보드로는 2개의 i960 칩이 사용되었고 자체 개발된 표준 컴퓨터 인터페이스 라이브러리(SCIL) 프로그램이 사용되었다. Irvine 컴파일러 회사의 개발환경과 Ada95 프로그래밍 언어가 OFP 개발에 사용되었다. OFP는 소프트웨어 모듈의 독립성을 위하여 3부분으로 구성된 1개의 컴퓨터소프트웨어형상품목으로 설계되었다. 일련의 비행시험을 통해 개발된 OFP를 검증하였으며, 소프트웨어 통합시험과 지상기능시험 등 관련 시험 또한 수행하였다.

• 사상체질의학회지
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• 제21권2호
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• pp.96-106
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• 2009

1. Objectives : The aim of this study was to survey the ordinary symptoms of TE type(Tae-eumin) and to compare the tendency of their symptoms according to the Exterior- or Interior- disease. 2. Methods : We recruited 659 TE type(Tae-eumin)-subjects in multi-oriental hospitals and researched their ordinary symptoms. Subjects were diagnosed by the Sasang Constitutional specialists in oriental hospitals, and had remarkable improvement in the chief complains after Sasang Constitutional Medication. Subjects were divided two groups. One group had the Exterior-cold disease and they took the prescription for the Exerior-cold disease(such as Taeumjowi-tang, Jowiseungcheong-tang, Nocyongdaebo-tang etc.). The other group had the Interior-febrile disease and they took the prescription for the Interior-febrile disease(such as Galgunhaegui-tang, Yeoldahanso-tang, Cheongsimyeonja-tang, Gongjinhugwon-dan etc.). All subjects answered the questionnaire about their symptoms. We found the differences of answers using the Chi-square test between-group comparisons. We analyzed using SPSS 12.0 for Korean. 3. Results and Conclusions : In symptoms, Quantity of meal(p=.009), Perspiration of head and face(p=.001), Aspect of Excrement(p=.027), Presence of pain after excrement(p=.001), Frequency of urination at night(p=.003), Clarity of urine(p=.041), Sleep during the day(p=.049), Warm or cold feeling on abdomen(p=.007), etc. are different according to the Exterior- or Interior- disease. We found the differences of symptoms between not only the constitutional types but also the types of disease.

• Radiation Oncology Journal
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• 제37권1호
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• pp.60-65
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• 2019

Purpose: The quality assurance (QA) chart rounds are multidisciplinary meetings to review radiation therapy (RT) treatment plans. This study focus on describing the changes in RT management based on QA round reviews in a single institution. Materials and Methods: After 9 full years of implementation, a retrospective review of all patients whose charts passed through departmental QA chart rounds from 2007 to 2015. The reviewed cases were presented for RT plan review; subcategorized based on decision in QA rounds into: approved, minor modifications or major modifications. Major modification defined as any substantial change which required patient re-simulation or re-planning prior to commencement of RT. Minor modification included treatment plan changes which didn't necessarily require RT re-planning. Results: Overall 7,149 RT treatment plans for different anatomical sites were reviewed at QA rounds. From these treatment plans, 6,654 (93%) were approved, 144 (2%) required minor modifications, while 351 (5%) required major modifications. Major modification included changes in: selected RT dose (96/351, 27%), target volume definition (127/351, 36%), organs-at-risk contouring (10/351, 3%), dose volume objectives/constraints criteria (90/351, 26%), and intent of treatment (28/351, 8%). The RT plans which required major modification according to the tumor subtype were as follows: head and neck (104/904, 12%), thoracic (12/199, 6%), gastrointestinal (33/687,5%), skin (5/106, 5%), genitourinary (16/359, 4%), breast (104/2387, 4%), central nervous system (36/846, 4%), sarcoma (11/277, 4%), pediatric (7/251, 3%), lymphoma (10/423, 2%), gynecological tumors (2/359, 1%), and others (11/351, 3%). Conclusion: Multi-disciplinary standardized QA chart rounds provide a comprehensive and an influential method on RT plans and/or treatment decisions.

• 한국컴퓨터정보학회논문지
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• 제19권6호
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• pp.49-59
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• 2014

최근 무선 센서 네트워크(WSN)이 침입 탐지와 생태, 환경, 대기, 산업, 교통, 화재 감시 등에 다양하게 적용되어 사용되고 있다. 본 논문에서는 에너지 효율적인 클러스터링 알고리즘을 제안한다. 제안 알고리즘은 수신전력을 바탕으로 하여 최적위치의 클러스터헤드를 선출하고 이를 통해 균일한 클러스터사이즈를 가지도록 한다. 또한 최대 깊이가 제한된 MST를 이용한 라우팅 트리를 구성하고 멀티 홉 전송을 통해 센서 노드의 위치에 관계없이 균일한 에너지 소모를 유도하도록 하였다. 이를 통해 제안 알고리즘은 기존의 LEACH나 HEED에 비해 노드의 에너지 소모를 감소시키고 균등한 에너지 소모를 유도하여 네트워크 수명을 증대시킬 수 있다. 시뮬레이션 결과 제안 알고리즘이 공평한 에너지 소모를 통해 네트워크 수명을 증대시킬 수 있음을 확인하였다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2016년도 춘계학술대회 및 임시총회
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• pp.33-33
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• 2016

Mycotoxins are toxic secondary metabolites produced by fungi. They can be present in where agricultural-based commodities are contaminated with toxigenic fungi. These mycotoxins cause various toxicoses in human and livestock when consumed. Small grains including corn, barley, rice or wheat are frequently contaminated with mycotoxins due to infection mainly by toxigenic Fusarium species and/or under environment favorable to fungal growth. One of the most well-known Fusarium toxin groups in cereals is trichothecenes consisting of many toxic compounds. Deoxynivalenol (DON), nivalenol (NIV), T-2 toxin, and various derivatives belong to this group. Zearalenone and fumonisin (FB) are also frequently produced by many species of the same genus. In order to monitor Korean cereals for contamination with Fusarium and other mycotoxigenic fungal species as well, barley, corn, maize, rice grains, and soybean were collected from fields at harvest or during storage for several years. The fungal colonies outgrown from the grain samples were identified based on morphological and molecular characteristics. Trichothecene chemotypes of Fusarium species or presence of FB biosynthetic gene were determined using respective diagnostic PCR to predict possible toxin production. Heavy grain contamination with fungi was detected in barley, rice and wheat. Predominant fungal genus of barley and wheat was Alternaria (up to 90%) while that of rice was Fusarium (~40%). Epicoccum also appeared frequently in barley, rice and wheat. While frequency of Fusarium species in barley and wheat was less than 20%, the genus mainly consisted of Fusarium graminearum species complex (FGSC) which known to be head blight pathogen and mycotoxin producer. Fusarium composition of rice was more diverse as FGSC, Fusarium incarnatum-equiseti species complex (FIESC), and Fusarium fujikuroi species complex (FFSC) appeared all at considerable frequencies. Prevalent fungal species of corn was FFSC (~50%), followed by FGSC (<30%). Most of FFSC isolates of corn tested appeared to be FB producer. In corn, Fusarium graminearum and DON chemotype dominate within FGSC, which was different from other cereals. Soybeans were contaminated with fungi less than other crops and Cercospora, Cladosporium, Alternaria, Fusarium etc. were detected at low frequencies (up to 14%). Other toxigenic species such as Aspergillus and Penicillium were irregularly detected at very low frequencies. Multi-year survey of small grains revealed dominant fungal species of Korea (barley, rice and wheat) is Fusarium asiaticum having NIV chemotype.

• Restorative Dentistry and Endodontics
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• 제28권6호
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• pp.491-497
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• 2003

The purpose of this study was to evaluate the correlation between hybrid layer thickness and bond strength using confocal laser scanning microscope and microtensile bond strength test of two adhesive systems. The dentin surface of human molars. sectioned to remove the enamel from the occlusal surface. Either Scotchbond Multi-Purpose(3M Dental Product, St. Paul, MN, U.S.A) or Clearfil SE Bond (Kuraray, Osaka, Japan) was bonded to the surface. and covered with resin-composite. The resin-bonded teeth were serially sliced perpendicular to the adhesive interface to measure the hybrid layer thickness by confocal laser scanning microscope. The specimen were trimmed to give a bonded cross-sectional surface area of $1\textrm{mm}^2$, then the micro-tensile bone test was performed at a cross head speed of 1.0 mm/min. All fractured surfaces were also observed by stereomicroscope. There was no significant differences in bond strengths the materials(p>0.05). However. the hybrid layers of three-step dentin adhesive system, SM, had significantly thicker than self-etching adhesive system. CS(p<0.05). Pearson's correlation coefficient showed no correlation between hybrid layer thickness and bond strengths(p>0.05). Bond strengths of dentin adhesive systems were not dependent on the thickness of hybrid layer.

• 대한치과재료학회지
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• 제43권1호
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• pp.43-50
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• 2016

The aim of this study was to investigate the effect of multiwall carbon nanotube functionalized with carboxyl group (MWCNT-COOH) on the mechanical properties of dental glassionomer cement (GIC). MWCNT-COOH was prepared by the acid oxidative method. The MWCNT-COOH was incorporated into a commercial GIC powder or liquid at 0.5 wt% or 1.0 wt%. The net setting time of the cements was measured in accordance with ISO 9917 (Dental water-based cement). Specimens for compressive strength ($4mm{\varphi}{\times}6mm$), diametral tensile strength ($6mm{\varphi}{\times}4mm$) and flexure strength with modulus ($2mm{\times}2mm{\times}25mm$) were prepared by mixing with the cement liquid and kept in water bath of $(37{\pm}1)^{\circ}C$. Mechanical tests were conducted in 1 d, 7 d, and 14 days at a cross-head speed of 1 mm/min. Compressive strength of GIC mixed with 0.5 wt% MWCNT-COOH increased significantly at 7 d. However, overall mechanical properties of GIC modified with MWCNT were not significantly increased with a delayed setting time, in comparison with control cement. Overall results indicated that the MWCNT/GIC composite cements showed a limited strengthening effect for dental glassionomer cement.

• 한국기계가공학회지
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• 제18권2호
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• pp.65-72
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• 2019

In long freight trains, there is a brake time delay in neighboring freight cars, which causes damage and fractures in the couplers, especially at their knuckle. A problem in the couplers of the cars can cause derailment and damages of human life and property. In this study, maximum forces on the couplers are studied when a long freight car brakes with the brake delay time and coupler gap. We make a dynamic model of 50 freight cars and couplers, applying contact between the couplers and a characteristic curve to express the force and displacement of the buffers using SIMPACK, which is a multi-body dynamics program. We use EN 14531-2, which is a standard of freight car brakes, to verify the dynamic model. Then, we compare the analyzed impact force with the coupler knuckle standard after applying the two carriages of a locomotive in the model based on the dispersed double head control system. The result shows that all coupler gap conditions satisfy the infinite lifetime of the material when the brake delay time is 0.1 second.