Cone beam형 전산화단층영상의 원리

최용석,김규태,황의환 대한구강악안면방사선학회 2006 Imaging Science in Dentistry Vol.36 No.3

The use of computed tomography for dental procedures has increased recently. Cone beam computed tomography (CBCT) systems have been designed for imaging hard tissues of the dentomaxillofacial region. CBCT is capable of providing high resolution in images of high diagnostic quality. This technology allows for 3-dimensional representation of the dentomaxillofacial skeleton with minimal distortion, but at lower equipment cost, simpler image acquisition and lower patient dose. Because this technology produces images with isotropic sub-millimeter spatial resolution, it is ideally suited for dedicated dentomaxillofacial imaging. In this paper, we provide a brief overview of cone beam scanning technology and compare it with the fan beam scanning used in conventional CT and the basic principles of currently available CBCT systems.

스위치드 릴럭턴스 전동기의 토오크 리플 저감을 위한 폴 형상 최적화

최용권,윤희성,황인성,고창섭 충북대학교 컴퓨터정보통신 연구소 2006 컴퓨터정보통신연구 Vol.14 No.1

최근 스위치드 릴럭턴스 전동기(Switched Reluctance Motor)는 고효율, 안정성, 용이한 가변 속도, 그리고 유지 보수의 불필요성 등의 장점으로 인하여 산업의 많은 분야에서 사용이 증대되고 있다. 그러나 SRM은 고정자와 회전자가 모두 돌극(Saliency) 구조를 이루며 펄스 형태의 여자 방식으로 구동되기 때문에 소음과 진동의 원인이 되는 토오크 리플이 크다는 단점을 갖는다. 토오크 리플 저감을 위한 기존의 연구는 주로 턴온 각 (θ_(on))과 턴오프 각 (θ_(off))조정, 고정자 극호(β_(s)) 그리고 회전자 극호 (β_(r))를 조정하는데 초점을 두었다. 그러나 고속 구동 시에는 여자 전류의 확립을 위한 충분한 시간이 필요하므로 스위칭 각도를 조정하여 토오크 리플을 저감하는 방법에는 한계가 있다. 따라서 본 논문은 턴온 각, 턴오프 각, 고정자 극호, 그리고 회전자 극호가 고정되어 있는 경우 고정자 돌극의 형상 변화를 통한 토오크 리플 저감법을 제안하고 반응표면법(Response Surface Methodology)을 이용하여 최적화를 수행하였다. Recently the switched reluctance motor(SRM) is highly expected to have more and more growing applications because it has many advantages over the other type motors such as high torque/weight ratio, robustness, easy variable speed and less maintenance. However, the SRM has large torque ripple which is caused by the excitation method of the pulse waveform and the saliency of both the stator and the rotor. The prior researches on the reduction of torque ripple are mainly focused on optimizing the switching angle, stator pole arcs, and rotor pole arcs. In high speed operation, however, it has a limitation to control the switching angle for the reduction of torque ripple because enough time is required in the establishment of exciting current. This paper shows that the torque ripple can be successfully minimized by optimizing the shape of the stator pole without controlling the switching time, stator pole arcs and rotor pole arcs.

마이크로 컨트롤러를 이용한 지능구조물의 진동제어시스템 개발

황재혁,홍의표,이원석,최용훈 한국항공대학교 항공우주산업기술연구소 2003 航空宇宙産業技術硏究所 硏究誌 Vol.13 No.-

본 논문에서는 유연구조물의 진동을 제거하기 위하여 압전 세라믹(PZT)을 감지기와 작동키로 이용하였다. 진동을 제거하기 위한 제어 방법은 위치 되먹임 제어와 속도 되먹임 제어 두가지 방법을 사용하였다. 위치 되먹임 제어는 구조물의 각 지점의 위치를 감지해 내고 이를 역으로 걸어 주는 것이고 속도 되먹임 제어는 유연부착물의 각 지점에서의 속도에 대한 정보를 역으로 걸어 주는 것이다. 즉, 압전 감지기의 감지 전압을 이용해서 속도 되먹임 제어를 할 수 있다. 적용된 두 제어 방법 모두 개회로일 때 보다 좋은 성능을 나타내었다. 그러나 위치 되먹임 제어가 스필오버(spill-over)가 심했고 속도 되먹임 재어보다 정착시간(Settling Time)이 더 길었다. 본 실험에서는 속도 되먹임 제어가 적은 에너지로도 위치 되먹임 제어보다 좋은 성능을 보였다. 제어시스템을 구축하기 위해서 마이크로 컨트롤러를 사용한 제어보도를 설계하고 제작하였다. 제어 보드에 사용된 마이크로 컨트롤러는 Intel 80c196ke를 사용하였으며 마이크로 컨트롤러의 A/D, D/A 기능을 보완하기 위해서 A/D, D/A 보드를 제작하였으며, 사용자 편의와 원거리 제어를 위해서 사용자 보드를 제작하였다. 본 실험에서 제작한 제어 보드는 본 실험에 쓰인 외괄보 뿐만 아니라 압전 세라믹을 이용한 모든 구조물의 능동진동제어에 쓰인 수 있도록 제작되었다.

원자력 사고후 쌀알과 배추내 ^90Sr 및 ^137Cs 농도 예측

최용호,임광묵,황원태,이한수,이창우 대한방사선 방어학회 2002 방사선방어학회지 Vol.27 No.3

원자력 사고후 시간경과에 따른 작물체내 핵종 농도를 보다 현실적으로 예측할 수 있는 방법을 수립하고 단위 건침적에 대하여 백미와 배추내 ^90Sr 및 ^137Cs의 50 년간 농도를 예측하였다. 비생육기 사고의 경우 농도는 두 핵종 모두 시간경과에 따라 서서히 감소하였고 50년 내내 ^90Sr이 ^137Cs보다 높았다. 생육기 사고의 경우 처음 1년간 농도는 비생육기 사고에 비해 대체로 ^90Sr은 최고 30 배, ^137Cs은 최고 1,000 배 정도까지 높았다. 50 년간의 누적농도는 백미에서는 비 생육기 사고의 경우 ^90Sr이, 생육기 사고의 경우 ^137Cs이 더 높았으나 배추에서는 어느 경우에나 ^90Sr이 더 높았다. 생육기 사고시 50년간의 누적농도에 대한 지배적 경로는 대체로 ^90Sr의 경우 뿌리흡수, ^137Cs의 경우 작물체 직접오염이었다. 재부유의 영향은 무시할 수 있을 정도였다. 예측 결과에 입각하여 사고 조건별로 대책의 방향을 제시하였다. A method of more realistically predicting radionuclide concentrations in crop plants varying with time after a nuclear accident was established to estimate 50 years' concentrations of ^90Sr and ^137Cs in polished rice seeds and Chinese cabbage for unit dry deposition. After non-growing season accidents, concentrations of both nuclides decreased gradually with time and ^90Sr concentrations were higher than those of ^137Cs throughout the whole period. Radionuclide concentrations in the 1st year after growing season accidents were on the whole higher than those after non-growing season accidents by factors of up to 30 for ^90Sr and up to 1,000 for ^137Cs. In polished rice seeds, the 50 years-integrated concentration was higher for ^90Sr than for ^137Cs after non-growing season accidents, whereas the opposite was true after growing season accidents. In Chinese cabbage, however, it was higher for ^90Sr than for ^137Cs after both types of the accident. Generally speaking, the dominant pathway for the integrated concentration after the growing season accident was root uptake for ^90Sr and direct plant contamination for ^137Cs. The effect of resuspension was negligible. Based on the predicted results, the direction of planning countermeasures was suggested for various accident conditions.

信用狀 通知銀行과 買入銀行에 대한 開設銀行의 地位

黃龍周,崔斗壽 인제대학교 1996 仁濟論叢 Vol.12 No.2

The essence of letter of credit transaction is conditional definite payment undertaking of the issuing bank, so in transaction with letter of credit, the existence of the issuing bank is essential. In this content, the role of the issuing bank is discussed by examining the relation among advising bank and negotiating bank out of monetary settling bank, that is parties concerned with letter of credit. First, advising bank has the trustship, representation and order for the issuing bank. The advising bank has the obligation to inform the content of L/C according to the ask and order of the issuing bank. The advising bank should have the close examination about the truth of outward show when he informs that. Second, negotiating bank acquires the right to ask reparation to advising bank according to the definte payment undertaking and reimbursement undertaking when he receives the bill of exchange from beneficiary. The issuing bank present the bill of exchange and shipping documents from beneficiary to issuing bank. The issuing bank has the legal relations about rights and obligations of the parties like advising bank and negotiating bank with monetary settling bank. And they have importer and exporter as customers respectively under the conditions of international trade transaction, so the issuing bank has huge effect on the whole transactions. The issuing bank should examine the documents from exporter to receive the suitable products in time with the regulations of L/C consistent to the monetary relations, let the exporter to receive the money in his residence with the definite payment undertaking under the conditions of L/C. In conclusion, the issuing bank should solve the probable problem of inconsistency of the time for safety of receiving the money and receiving the products, that functions for satisfactory international sale transactions.

초음파영상을 이용한 정상 교근의 평가

황형주,김규태,최용석,황의환 대한구강악안면방사선학회 2008 Imaging Science in Dentistry Vol.38 No.2

Purpose : To assess the internal echo intensity and morphological variability of masseter muscles on ultrasonography and to establish diagnostic criterion of estimation. Materials and Methods : Participants consisted of 50 young adults (male 25, female 25) without pathologic conditions and with full natural dentitions. Sonographic examinations were done with real time ultrasound equipment as Logiq 500 (GE Medical Systems, Seoul, Korea) at 3 parts according to lines paralleling with ala-tragus line as reference line. The thickness and area of masseter muscles according to reference line in cross-sectional images were measured at rest and at maximum contraction. The visibility and width of the internal echogenic intensity of the masseter muscles were also assessed and the muscle appearance was classified into 4 types. Data were statistically analyzed by paired t-test and x²-test. Results : 1. When comparing the thickness and area of masseter muscles concerning with gender, there was few significant difference between right and left sides, however, there were significant differences between males and females except for the greatest thickness of left side. 2. The changes of the greatest thickness and the area between rest and maximum contraction showed that the part of the least thickness manifested more increase at maximum contraction. 3. Each part the manifestations of the internal echogenic intensity of the masseter muscles were different depending on the locations. But there was no statistically significance. Conclusion : Changes of muscles thickness with contraction and internal echogenic intensity with locations showed great disparity within the masseter muscles, which will be diagnostic criteria for pathophysiologic and anatomic changes of masseter muscles.

MRI 연속영상의 윤곽검출과 3차원영상 재구성

황용호,최우영 명지대학교 대학원 1997 대학원논문집 Vol.1 No.-

Snakes is an active contour model for representing image contours. To detect boundary on MRI sequential images, we proposed a method based on snakes. Because there is spatial correlation between two adjacent MRI images, an energy term related with spatial correlation was added to Snakes energy formulation. A measure of shape similarity called the BMD was used to evaluate the accuracy of the algorithm. The average BMD value for the modified alogrithm's result is higher than existing Greedy algorithm's. And 3D image was reconstructed by applying triangle interpolation to the detected boundary on each slice.

재조합효모를 이용한 배양 중 pH변화에 따른 인간 라이소자임의 대량생산

최선욱,이승철,황용일 慶南大學校 附設 基礎科學硏究所 1998 硏究論文集 Vol.12 No.-

Human lysozyme(HLT ; EC 3.4.1.17) is a cell wall lytic enzyme which consists of 130 amino acid residues. We have already prepared an artificial HLY gene from chemically synthesized 38-oligomer with high codon usage in S. cerevisiae. For directing the synthesis and secretion of HLY in S. cerevisiae, a YEp 2-㎛ circle-based vector, pHK501 was constructed by inserting the HLY gene. First, for HLY production during recombinant cell fermentations, compositions of culture mediums, pH, and glucose concentration were optimized. The various complex media containing yeast extract were used to increase the cell mass and HLY activity, but were not recommendable because of low plasmid stability during fermentations. Higher extracellular HLY activity was obtained in the synthetic medium containing 4% initial glucose. Higher HLY activity was observed when pH was controlled to 5.5 in comparison with pH-uncontrolled fermentations. Second, for enhancing the secretion of HLY in recombinant S. cerevisiae, a pH shift process was examined. After reaching stationary growth phase, extracellular HLY activity was significantly increased when pH in culture broth was purposely dropped to 3.0. This pH shift process seems to be very effective strategy for secretion of HLY in periplasmic space.

螢光像 測定法으로 分析한 HUMACTBP2 遺傳座位에 대한 韓國人의 遺傳的 多樣性과 法醫學的 有用性

황적준,남용석,최하주,이혜린,한길로 大韓法醫學會 1997 대한법의학회지 Vol.21 No.1

The HUMACTBP2 locus was investigated to collect population genetic data in the Korean population and to evaluate the applicability for the forensic field. An Automatic fluorescent-based sequencer (377 automatic DNA sequencer, ABI) was used to detect amplified fragments of the HUMACTBP2 locus electrophoresed on 4% denaturing polyacrylamide sequencing gels. ACTBP2 allelic ladder consisting of different sizes of 18 alleles was constructed and employed as an internal size standard in combination with a GS-350 size standard for precision of allele-band sizing. By utilizing different fluorescent dyes, both the allelic ladders and samples were able to be analyzed in the same lane by 99% precision of allele-band sizing. Among the Korean population (n=224), 26 alleles in the range of 239-313 bp are determined. Allele No. 6 is found 45 times (0.100) which is mostly frequent, and the rest of allele is distributed with their relative frequency of 0.112-0.100. The comparison between observed and expected numbers of homozygous and heterozygous individuals confirms that ACTBP2 locus is in the state of Hardy-Weinberg equilibrium among the Korean population. The heterozygosity is 0.9389±0.0034(93.89%), and the power of discrimination)PD) and power of exclusion(PEX) are calculated to be 0.991(99.1%) and 0.890(89.0%), respectively, showing the high informativeness for individual identification. Thus, these results mean that the HUMACTBP2 locus can effectively be used for the forensic application.

쌍방향 Compunication Local Network 구축과 활용

최계호,김용현,이형민,김정숙,황용하 대구산업정보대학 2001 논문집 Vol.15 No.-

Since we are in the transitory era from the age of industrialization to the age of information, it is necessary to accomplish an effective localization of the information. Accordingly, the college tries to construct the bi-directional Communication Local Network so that we can provide the local design companies with technical information and that we can achieve the characterization of the college and its differentiation from the local colleges, which will help us produce the better professionals and eventually provide us the foothold that will make the college a heralding force of the national development and the localization of the information. With the CLN research center, the college can play a key role in providing the necessary information and technologies for the design-related companies in Kyeongsangbuk Province and become a corner stone for the localization of the information and the information-oriented nation.