• Journal of applied mathematics & informatics
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• 제14권1_2호
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• pp.81-96
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• 2004

The level-m scaled circulant factor matrix over the complex number field is introduced. Its diagonalization and spectral decomposition and representation are discussed. An explicit formula for the entries of the inverse of a level-m scaled circulant factor matrix is presented. Finally, an algorithm for finding the inverse of such matrices over the quaternion division algebra is given.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.448-452
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• 2002

We report the number of calibration and test for acoustic field which were conducted in KRISS between the year of 1990 and 2001. The items contain sound level meter and calibrator for calibration and sound absorption coefficient, transmission loss, sound pressure level of siren, sound pressure level and power of acoustic instrument and relative accessories for test. The data show that the number of them have been increased continuously.

• 대한수학회보
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• 제58권5호
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• pp.1149-1161
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• 2021

In this paper, we present new bounds on the fundamental units of real quadratic fields ${\mathbb{Q}}({\sqrt{d}})$ using the continued fraction expansion of the integral basis element of the field. Furthermore, we apply these bounds to Dirichlet's class number formula. Consequently, we provide computational advantages to estimate the class numbers of such fields. We also give some numerical examples.

• 수산해양교육연구
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• 제2권1호
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• pp.50-56
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• 1989

The authors investigated the present status of employment of graduates from ship-boarding departments, Department of Fishing Technology, of Marine Engineering in National Fisheries University of Pusan from 1974 to 1988 by communication of every kind. The prospects of the graduates were studied on the bases of the present status of employment The results obtained can be shown as follows ; 1. In Department of Fishing Technology, the number of graduates who are engaged in major field is 562 (81%) among total members of graduates 693, and fishing vessel officer and fisheries company officer is 308(55%), 215(38%) respectively among the above members of employment in major field. 2. In Department of Marine Engineering, the number of graduates who are engaged in major field is 468(74%) among total members of graduates, 634, and engine and machinery field officer, merchant vessel officer is 331(71%), 89(19%) among above members of employment in major field respectively. 3. Developement of deep sea fisheries and industry of engine and machinery seems to graduates easy to get their jobs in major field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.107-109
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• 2007

Pancake windings have merits that are easier to make high field magnets and replace windings when an accident happens and windings are aged. The current of the whole magnet consisted of windings connected in series was limited by the minimum current of the top and bottom pancake windings where maximum perpendicular magnetic field was applied. This paper propose a optimal design of a HTS magnet excited by a single source, where evolution strategy was adopted for optimal design algorithm. A magnet consisted of 8 BSCCO pancakes was chosen to prove the effectiveness of this optimal design method. Magnetic field at the center of a magnet was chosen as the object function and it was used maximized. Results of the optimal design shows that the increment of the number of turns of the pancake winding make the magnetic field of the center of the magnet increase but the current of the winding decrease for the larger perpendicular magnetic field.

• 한국환경복원기술학회지
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• 제20권6호
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• pp.79-92
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• 2017

To offer the basic data of vegetation restoration by buried seed of soil, this research was conducted at bare land and abandoned field in Yesan-gun. Germination plants of buried seed were consisted of 40 taxa (37 species, 3 varieties) in bare land, and 41 taxa (37 species, 4 varieties) in abandoned field. Classification of germination plants by family was the most in Gramineae, and emergent frequency of plots was the highest of Digitaria ciliaris. The soil depth of the most plants appearance was 2~5cm in bare land and 5~10cm in abandoned field, and the soil depth of the most population appearance was 0~2cm both in bare land and in abandoned field. Population number of buried seed germination was decreased according to soil depth. Crepidiastrum sonchifolium was a plant that population number of buried seed germination is the most. Similarity index was 0.33 in aerial part plants and buried seed plants, and 0.55 in bare land and abandoned field.

• 한국음향학회지
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• 제22권8호
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• pp.660-669
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• 2003

본 논문은 음원 근처의 홀로그램 평면에서 측정된 음압에 대한 상호 파워 스펙트럼으로부터 홀로그램 평면에서의 음압 분포를 구하고 획득된 음장을 공간 변환하여 음원의 음장을 구하기 위한 이론을 설명하였으며, 홀로그램 평면에서의 상호 파워 스펙트럼으로부터 모든 지점에서의 음압을 구하기 위해 비선형 방정식에 대한 Taylor 급수를 전개하고 Newton-Raphson 법을 이용하여 계산하는 방법과 음원 영역으로의 역방향 전파시 발생되는 오차를 줄이기 위한 파수 필터를 제시하였다. 무한 배플 내의 원판형 진동체 수중 음원에 대한 모의실험을 통해 결과를 고찰하고 제시된 이론을 검증하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권2호
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• pp.103-108
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• 2004

This paper shows the simulation of electric field distribution and removal characteristics of Escherichia coli for water discharge tube with globular $SiO_2$. At the experiments of the removing Escherichia coli used the discharge tube with globular dielectric($SiO_2$), because the electric field is increased when applied voltage is increased, the removed ratio of Escherichia coli was related with increasing of applied voltage. When a passing number of test water in water discharge tube is increased, the removed ratio of Escherichia coli is increased because passing number of territory with electric field is increased. When diameter of globular dielectric($SiO_2$) is increased, the removed time of Escherichia coli was decreased because electric field for dielectric polarization of globular dielectric($SiO_2$) was increased. Also, the removed ratio of Escherichia coli of the water discharge tube with globular dielectric($SiO_2$) was measured higher than the removal ratio of the discharge tube without globular dielectric($SiO_2$)

• 대한방사선치료학회지
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• 제25권2호
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• pp.145-151
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• 2013

목 적: 본 연구에서 우리는 6 MeV 전자선의 조사야 확대에 따른 선량변화가 차폐물질 원자번호와 관계가 있음을 알아보고 그 영향인자를 분석 하고자 한다. 대상 및 방법: 먼저 평행평판형 전리함(Exradin P11)을 $25{\times}25cm^2$ 폴리스티렌 팬텀표면에 평탄하게 끼운다. 허용투과율 5% 두께의 알루미늄, 구리, 납 물질들을 팬텀 상단에 차폐시킨 후 조사야 $6{\times}6$, $10{\times}10$ 그리고 $20{\times}20cm^2$별로 측정하였다. 조사조건은 선원-표면간거리 100 cm에서 기준조사야인 $10{\times}10cm^2$에 6 MeV 전자선을 이용하여 100 cGy 조사하였다. 다음으로 MCNP (Monte Carlo N Particle Transport Code)를 이용하여 각 물질 통과 후 발생되는 광자수, 전자수, 그리고 축적에너지를 계산하였다. 결 과: 허용투과율 5% 두께에 대한 차폐물 종류에 따른 측정결과 조사야 $10{\times}10cm^2$을 기준으로 한 $6{\times}6cm^2$과 $20{\times}20cm^2$의 두께변화율은 알루미늄에서 각각 +0.06%와 -0.06%, 구리에서 각각 +0.13%와 -0.1%, 납에서 각각 -1.53%와 +1.92%였다. 계산결과 조사야 $10{\times}10cm^2$ 대비 $6{\times}6cm^2$, $20{\times}20cm^2$의 축적에너지는 차폐를 하지 않았을 경우 각각 -4.3%와 +4.85%, 알루미늄 사용 시 각각 -0.87%와 +6.93%, 구리 사용 시 각각 -2.46%와 +4.48%, 납 사용 시 각각 -4.16%와 +5.57%였다. 광자수의 경우 차폐를 하지 않았을 경우 각각 -8.95%와 +15.92%, 알루미늄 사용 시 각각 -15.56%와 +16.06%, 구리 사용시 각각 -12.27%와 +15.53%, 납 사용 시 각각 -12.36%와 +19.81%였다. 전자수의 경우 차폐를 하지 않았을 경우 각각 -3.92%와 +4.55%, 알루미늄 사용 시 각각 +0.59%와 +6.87%, 구리 사용 시 각각 -1.59%와 +3.86%, 납 사용 시 각각 -5.15%와 +4.00%였다. 결 론: 본 연구로 조사야 증가함에 따른 차폐물 두께가 저 원자번호에서 감소하며, 고 원자번호에서는 증가함을 볼 수 있었으며, 계산을 통해 저 원자번호물질에서는 저지방사선, 고 원자번호물질에서는 산란전자가 영향을 주는 것을 알 수 있었다.

• Kyungpook Mathematical Journal
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• 제56권4호
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• pp.1135-1140
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• 2016

Let A be an abelian variety over a global field K. We know [6, 7] that, in many cases, the average number of n-torsion points of A over various residue fields of K, takes the minimal possible value. In this article, we study several defect cases by calculating the number of Galois orbits.