• 천문학논총
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• 제19권1호
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• pp.129-133
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• 2004

In the past, radio astronomers have sought isolation from man-made signals by placing their telescopes in remote locations. These measures may no longer safeguard scientific observations, since NGSO satellite systems, particularly low-Earth orbit (LEO) systems, are usually designed to provide global or wide regional coverage. Further, radio astronomers have historically made their observations in the frequency bands allocated for their use by the member countries of the International Telecommunication Union (ITU). The science of radio astronomy could be adversely impacted by the deployment of large constellations of new non-geostationary orbiting (NGSO) satellites for telecommunications, navigation and Earth observation, and the proliferation of new, high-power broadcasting and telecommunication satellites in geostationary (GSO) orbits. Radio telescopes are extremely sensitive, and, in certain situations, signals from satellites can overwhelm the signals from astronomical sources. This paper describes the problem in detail and identifies ways to mitigate it without adversely affecting the continued vigorous growth of commercial space-based telecommunications.

• 대한기계학회논문집A
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• 제21권2호
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• pp.281-287
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• 1997

In the conventional inverse modeling method for on-line modeling of the secondary path transfer function, the signal to noise ratio between the arbitrary random signal and the plant noise have to keep at -10 - -20 dB. For these reasons, the modeling can't be exactly implemented by the conventional method alone and the convergence time for modeling becomes too long. In this study, by combining the conventional inverse modeling method with an adaptive line enhancer, or with an adaptive noise canceller, a rigorous transfer functions of secondary path modeling and the control of a primary noise have been implemented simultaneously.

• Journal of Korean Neurosurgical Society
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• 제29권8호
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• pp.1063-1068
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• 2000

Objectives : To determine the contribution of cranial magnetic resonance angiography(MRA) for the evaluation of patients with ischemic cerebrovascular accident. Methods : Magnetic resonance image(MRI) and MRA studies performed on 34 patients with ischemic stroke were retrospectively reviewed with the clinical records. Results : There were 9 transient ischemic attacks and 25 completed strokes in our series. Twenty-three of 34 MRA examinations(68%) were positive for stenosis or occlusion. The distribution of stenotic or occlusive vascular lesions were correlated with the location of infarction in 22 of the 23 positive cases(96%). MRA provided additional information not obtained from the MRI in 19 cases(56%). Conclusions : Vascular lesions demonstrated on intracranial MRA show a high correlation with infarct distribution. MRA provided information adjunctive to conventional MRI in a majority of cases. We conclude that MRA is an important noninvasive component of the complete evaluation of ischemic stroke.

• 산업경영시스템학회지
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• 제39권3호
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• pp.1-9
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• 2016

NSS (Navigation satellite system) provides the information for determining the position, velocity and time of users in real time using satellite-networking, and is classified into GNSS (Global NSS) and RNSS (Regional NSS). Although GNSS services for global users, the exactitude of provided information is dissatisfied with the degree required in modern systems such as unmanned system, autonomous navigation system for aircraft, ship and others, air-traffic control system. Especially, due to concern about the monopoly status of the countries operating it, some other countries have already considered establishing RNSS. The RNSS services for users within a specific area, however, it not only gives more precise information than those from GNSS, but also can be operated independently from the NSS of other countries. Thus, for Korean RNSS, this paper suggests the methodology to design the satellite constellation considering the regional features of Korean Peninsula. It intends to determine the orbits and the arrangement of navigation satellites for minimizing PDOP (Position dilution of precision). PGA (Parallel Genetic Algorithm) geared to solve this nonlinear optimization problem is proposed and STK (System tool kit) software is used for simulating their space flight. The PGA is composed of several GAs and iterates the process that they search the solution for a problem during the pre-specified generations, and then mutually exchange the superior solutions investigated by each GA. Numerical experiments were performed with increasing from four to seven satellites for Korean RNSS. When the RNSS was established by seven satellites, the time ratio that PDOP was measured to less than 5 (i.e. better than 'Good' level on the meaning of the PDOP value) was found to 94.3% and PDOP was always kept at 10 or less (i.e. better than 'Moderate' level).

• 대한수의학회지
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• 제33권3호
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• pp.479-486
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• 1993

This study was attempted co develope a method for detection of Theileria sergenti infection on the basis of hybridization of parasite DNA with a probe. For construction of a T sergenti genomic library, T sergenti DNA was digested completely with Bam-HI and the fragments were ligated into the Bam-HI site of pUC-19 before transformation of Escherichia colistrain JM83. To detect clones containing the parasite's DNA sequences, a genomic DNA library of T sergenti constructed in pUC-19 was screened by cracking and Southern hybridization. Seven colonies were chosen from 29 colonies which were screened by transformation of Escherichia coli strain JM83. Seven transformants were comfirmed from seven colonies by cracking. The sizes of transformants were about 5Kb, 5.7Kb, 4.3Kb, 7.75Kb, 7.85Kb, 5.8Kb, 3.8Kb, respectively. DNA inserts, T sergenti DNA, and bovine DNA were hybridized with radio-labelled T sergenti DNA. Two($pT_1$, $pT_1$) of the seven inserts and T sergenti DNA reacted strongly but another 5 inserts and bovine DNA showed weak reation. All of the DNA inserts were not reaction, but T sergenti DNA were very weakly and bovine DNA were strongly reacted to hybridization with radio-labelled bovine DNA. Therefore, we obtained total 7 T sergenti DNA fragments in this study.

• 한국융합학회논문지
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• 제13권4호
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• pp.307-313
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• 2022

차량 실내소음이 엔진의 고출력화와 경량화로 인해 더욱 심각해져 엔진진동의 저감의 중요성이 높아지고 있다. 최근 엔진진동 저감의 대표적인 방법으로 밸런스샤프트 부착이 제시되고 있다. 밸런스샤프트는 피스톤과 콘로드 등의 왕복운동에서 발생하는 진동을 임의의 편심질량을 이용하여 상쇄시키는 장치이다. 따라서 밸런스샤프트는 연비향상 및 차량의 승차감을 동시에 향상시킬 수 있다. 본 논문은 엔진구조로 인해 발생하는 관성력을 유도하고 이를 상쇄하기 위한 밸런스샤프트의 불평형량과 형상을 제시한다. 제시된 두가지 형상의 밸런스샤프트를 ADAMS 다물체동역학 모델로 구현하고, 이를 동역학 시뮬레이션을 통해 실제 거동상태에서의 관성력의 저감을 확인하였다.

• 대한기관식도과학회지
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• 제2권2호
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• pp.232-237
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• 1996

Burning and lump sensation in the throat is a common disorder in middle aged woman. It is generally considered to be a neurotic origin but its pathophysiology is still remained unknown. The purpose of this study was to evaluate the prevalence of the Pharyngoesophageal structural lesions and the esophageal motility disorders among the patients with globus pharyngeus and to elucidate whether any specific manometric abnormality might have any causative role in the pathogenesis of the globus sensation, and we also wanted to know whether such tests were necessary in evaluating those patients. Structural lesions were demonstrated in 21 cases(17.5 %) among 120 patients. But among 44 controls, there were also Two cases(4.5 %) of structural lesions, and there was less significantly difference in the prevalence of the structural lesions between the patients and controls(p=0.0625) Manometric abnormalities over the lower esophageal sphincter and the lower esophageal body were demonstrated in 28 cases (23.3 %) of the patients, while only one case (2.3 %) of the controls revealed such abnormality ( p=0.0037). Various manometric parameters of the upper esophageal sphincter and pharynx showed no difference between the patients and controls except the upper esophageal sphincter pressure at lateral sides which was lower in patients than in controls (p=0.0034). Globus sensation is a kind of symptom of esophageal dysmotility, and esophageal manometry is necessary to detect such abnormality in patients with globus sensation, Careful physical examination is also necessary to detect structural lesions in the pharynx and esophagus.

• Plant Biotechnology Reports
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• 제5권1호
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• pp.27-34
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• 2011

Jasmonates control diverse plant developmental processes, such as seed germination, flower, fruit and seed development, senescence and tuberization in potato. To understand the role of methyl jasmonate (MeJA) in potato tuberization, the Arabidopsis JMT gene encoding jasmonic acid carboxyl methyltransferase was constitutively overexpressed in transgenic potato plants. Increases in tuber yield and size as well as in vitro tuberization frequency were observed in transgenic plants. These were correlated with JMT mRNA level-- the higher expression level, the higher the tuber yield and size. The levels of jasmonic acid (JA), MeJA and tuberonic acid (TA) were also higher than those in control plants. Transgenic plants also exhibited higher expression of jasmonate-responsive genes such as those for allene oxide cyclase (AOC) and proteinase inhibitor II (PINII). These results indicate that JMT overexpression induces jasmonate biosynthesis genes and thus JA and TA pools in transgenic potatoes. This results in enhanced tuber yield and size in transgenic potato plants.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.935-943
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• 2015

Permanent magnetic actuators (P.M.A.s) are widely used to drive medium-voltage-class vacuum circuit breakers (V.C.B.s). In this paper, a method for design optimization of a P.M.A. for V.C.B.s is discussed. An optimal design process employing the response surface method (R.S.M.) is proposed. In order to calculate electromagnetic and mechanical dynamic characteristics, an initial P.M.A. model is subjected to numerical analysis using finite element analysis (F.E.A.), which is validated by comparing the calculated dynamic characteristics of the initial P.M.A. model with no-load test results. Using tables of mixed orthogonal arrays and the R.S.M., the initial P.M.A. model is optimized to minimize the weight of the permanent magnet (P.M.) and to improve the dynamic characteristics. Finally, the dynamic characteristics of the optimally designed P.M.A. are compared to those of the initially designed P.M.A.

• 한국콘텐츠학회논문지
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• 제10권5호
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• pp.407-415
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• 2010

본 연구는 충북 제천지역의 전통호텔 건립에 대한 타당성과 선호도를 파악하고, 향후 개발방향에 대한가이드라인을 제시하고자 한다. 설문지는 제천의 인근지역(단양, 청주, 원주)에 각 50부씩, 수도권은 100부를 포함한 300부를 배포하여 248부를 회수하여 분석한 결과는 다음과 같다.1. 전통숙박시설의 건축형태는 외관(한옥)/내부(서양식)의 절충형, 10만원 미만의 숙박요금, 전통음식점, 전통체험관 및 교육시설의 부대시설이 필요한 것으로 나타났다. 2. 전통숙박시설의 이용목적에서 적절한 숙박요금과 위치(주변 관광지와의 연계)를 중요하게 생각하는 것으로 나타났다. 3. '한옥과 서양식의 혼합형'의 건축형태에서 10만원 또는 15만원대의 객실요금, 자연친화적이면서 전통문화를 체험할 수 있는 공간을 가장 선호하는 것으로 나타났다. 4. 건축형태와 전통숙박시설에서 '한옥/서양식 절충형'은 객실/식음료의 적절한 가격, 청결과 매우 밀접한 관계가 있는 것으로 나타났다.