• 천문학회보
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• 제41권2호
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• pp.66.2-66.2
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• 2016

KASI and NAOJ are making collaborating efforts to implement faster mapping capability into the new 275-500 GHz Atacama Submillimeter Telescope Experiment focal plane array (FPA). Feed horn antenna is one of critical parts of the FPA. Required fractional bandwidth is almost 60 % while that of traditional conical horn is less than 50 %. Therefore, to achieve this wideband performance, we adopted a horn of which the corrugation depths have a longitudinal profile. A profiled horn has features not only of wide bandwidth but also of shorter length compared to a linear-tapered corrugated horn, and lower cost fabrication with less error can be feasible. In our design process the flare region is represented by a cubic splined curve with several parameters. Parameters of the flare region and each dimension of the throat region are optimized by a differential evolution algorithm to keep >20 dB return loss and >30 dB maximum cross-polarization level over the operation bandwidth. To evaluate RF performance of the horn generated by the optimizer, we used a commercial mode matching software, WASP-NET. Also, Gaussian beam (GB) masks to far fields were applied to give better GB behavior over frequencies. The optimized design shows >23 dB return loss and >33 dB maximum cross-polarization level over the whole band. Gaussicity of the horn is over 96.6 %. The length of the horn is 12.5 mm which is just 57 % of the ALMA band 8 feed horn (21.96 mm).

• 한국산학기술학회논문지
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• 제12권10호
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• pp.4642-4647
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• 2011

평면 변형률 상태에 있는 탄성지반의 해를 변분법을 적용하여 유도하여 보았다. 변분법 적용시 종방향 변위분포 함수는 선형함수를 고려하였다. 탄성지반상에 작용하는 하중조건은 집중하중과 분포하중을 고려하였는데 집중하중 작용시 탄성지반의 종방향 변위분포양상은 하중 작용점에서 멀어질수록 변위가 급격하게 감소하는 양상을 나타내었다. 등분포하중 작용시 지표면 변위는 압축층 두께에 대한 재하폭의 반의 비(B/H)값이 클수록 하중재하부분 아래에서 보다 균등하게 발생하였다. 또한 하중재하부분을 벗어난 영역에서는 B/H 값이 커질수록 하중재하 모서리 부분으로부터 짧은 거리에서 변위가 0에 수렴하였다.

• 대한인간공학회지
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• 제16권1호
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• pp.29-45
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• 1997

This study aims at designing sleeves which are suitable for arm shapes and arm movements. With the samples of of ordinary 24 women aged from 20 to 22, the arm shapes and movements were measured 3-dimensionally using a motion analyzer and a sonic digitizer, and then clasified into three characteristic types (A, B, and C). Our analysis leads to the following conclusion. The factors classifying arm shapes are the length from acromion to posterior armpit point, arm hole length, the cap height, difference in height between anterior and posterior armpit points, armhole circumference, upper arm circumferemce, armhole depth, and underarm circumference. The characteristics of arm type A is that the armhole depth and the length from acromion to posterior armpit point are the largest, while the circumference inbe- tween upper arm and elbow is the smallest among the three arm types. Thus, the large circumference difference between upper and lower arms is the most notable in arm type A. The factors classifying arm shapes for arm type B are the smallest except for the circumference inbetween upper arm and elbow which is larger than that for arm type A. The circumference difference betweemn upper and lower arms is small for arm type B. Arm type C has the smallest armhole depth, while other factors are similar to those for arm type B. In type C, the size of upper arm is comparatively small on the frontal plane, while it is the largest on the sagital plane.

• 한국정보통신학회논문지
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• 제18권10호
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• pp.2339-2344
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• 2014

마이크로스트립 선로 형태의 전송선로 밑면에 플로팅 동판을 위치시키면 플로팅 동판과 접지면 사이의 단락 또는 개방 연결에 따라 전송선로는 마이크로스트립 선로 또는 코플라나 선로 형태로 동작하게 된다. 이러한 동작은 하나의 전송 선로 폭에 대해 서로 다른 두 개의 특성 임피던스를 가질 수 있음을 의미한다. 플로팅 동판이 존재하는 마이크로스트립 전송 선로를 이용하여 안정적인 입력 정합 상태를 가지며 조건에 따라 단순히 신호를 전달하는 2-단자 전력 전송 선로 또는 전력 분배가 가능한 2-way 전력 분배 회로로 동작할 수 있는 가변 전송선로를 제안 및 제작하였다. 제안된 회로는 코플라나 선로로 동작하는 경우에는 전력 전송 선로로 동작하고, 마이크로스트립 선로로 동작하는 경우에는 2-way 전력 분배 회로로 동작한다. 제작된 가변 전송 선로는 700 MHz 이상의 주파수에서 전력 전송 선로로 동작하는 경우 -0.2 dB 이내의 전달 손실($S_{21}$)과 -15 dB 이하의 반사 계수($S_{11}$)를 보였으며, 전력 분배 선로로 동작하는 경우에는 -10 dB 이하의 반사 계수($S_{11}$), -3.8 dB이내의 전달 손실($S_{21}$ or $S_{31}$), ${\pm}0.3dB$이내의 출력 전력차($S_{21}/S_{31}$)를 보였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.21.1-21.3
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• 2019

Background: Treatment planning the correction of a transverse maxillary occlusal plane cant often involves a degree of qualitative "eyeballing", with the attendant possibility of error in the estimated judgement. A simple chair side technique permits quantification of the extent of asymmetry and thereby quantitative measurements for the correction of the occlusal plane cant. Methods: A measuring instrument may be constructed by soldering the edge of a stainless steel dental ruler at 90° to the flat surface of a similar ruler. With the patient either standing in natural head position, or alternatively seated upright in the dental chair, and a dental photographic retractor in situ, the flat under-surface of the horizontal part of this measuring instrument is placed on a unilateral segment of a bilateral structure, e.g. the higher maxillary canine orthodontic bracket hook. The vertical ruler is held next to the contralateral canine tooth, and the vertical distance measured directly from the canine bracket to the flat under-surface of the horizontal part of the measuring instrument. Results: This vertical distance quantifies the overall extent of movement required to level the maxillary occlusal plane. Conclusions: This measuring instrument and simple chair side technique helps to quantify the overall extent of surgical levelling required and may be a useful additional technique in our clinical diagnostic armamentarium.

• Journal of Astronomy and Space Sciences
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• 제23권1호
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• pp.19-28
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• 2006

The noise temperature of existing millimeter-wave receivers is already within two or three times quantum noise limit. One of practical ways to increase the observation speed of single dish radio telescope without longer integration time is use of multi-beam focal plane array receiver as demonstrated in several large single dish radio telescopes. In this context the TRAO (Taeduk Radio Astronomy Observatory), which operates a 143n Cassegrain radio telescope, is planning to develop a 4 x 4 beams focal plane array SIS receiver system for 86-115 GHz band. Even though millimeter-wave HEMT LNA-based receivers approach the noise temperature comparable to the SIS receiver at W-band, it is believed that the receiver based on SIS mixer seems to offer a bit more advantages. The critical part of the multi-beam array receiver will be sideband separating SIS mixers. Employing such a type of SIS mixer makes it possible to simplify the quasi-optics of receiver. Otherwise, an SSB filter should be used in front of the mixer or some sophisticated post-processing of observation data is needed. In this paper we will present a preliminary design concept and components needed for the development of a new 3 mm band multi-beam focal plane array receiver.

• Structural Engineering and Mechanics
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• 제6권2호
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• pp.143-159
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• 1998

The objective of this present work is to estimate the failure loads, associated maximum transverse displacements, locations and the modes of failure, including the onset of delamination, of thin, square symmetric laminates under the action in-plane positive (+ve) shear load. Two progressive failure analyses, one using the Hashin criterion and the other using a Tensor polynomial criterion, are used in conjunction with finite element method. First order shear deformation theory along with geometric non-linearity in the von Karman sense have been employed. Variation of failure loads and failure characteristics with five type of lay-ups and three types of boundary conditions has been investigated in detail. It is observed that the maximum difference between failure loads predieted by various criteria depends strongly on the laminate lay-up and the flexural boundary restraint. Laminates with clamped edges are found to be more susceptible to failure due to transverse shear (ensuing from the out of plane bending) and delamination, while those with simply supported edges undergo total collapse at a load slightly higher than the fiber failure load. The investigation on negative (-ve) in-plane shear load is in progress and will be communicated as part-II of the present work.

• 대한치과교정학회지
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• 제17권1호
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• pp.135-148
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• 1987

To investigate the relationship between craniofacial growth and bone maturity of the hand wrist in normal occlusion, the author took cephalogram and handwrist radiogram of 391 students (male 192, female 199) and assessed the measurements of cephalogram according to skeletal maturity stages of the hand and wrist. In this study, four skeketal stages and 36 linear, angular measurements of the cephalometrics were selected. In hand-wrist X-ray the bones used to determine skeletal maturity were the middle phalanges of the third finger, and distal epiphysis of the radius. In cephalogram, the landmark used to measure the angle and length were N, S, Po., Ar., Go., Me., Gn., Pog., Point B, Point A, ANS, PNS, Or., U1, L1, U6, L6 etc.. The results were as follows, 1. The table of mean, standard deviation, p-value from measurements were made in each group and both sex. 2. The increased measurements according to skeletal maturity were anterior cranial bese length, posterior cranial base length, ramus height, anterior facial height, posterior facial height, L1 to mandibular plane (mm), facial plane angle. In contrast to, decreased measurements were genial angle, facial cnvexity and facial plane angle. 3. Denture pattern measurements (IMPA, FMIA, occlusal plane to Go-Gn, interincisal angle, U1 to SN plane, U1 to SN plane, U1 to facial plane, L1 to facial plane etc.) .had nothing to do with skeletal maturity. 4. Skeletal maturity had close relationship with craniofacial growth, but had little to do with tooth development.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제11권1호
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• pp.1-14
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• 2004

Due to the development of computer network and mobile communications, the security in image data and other related source are very important as in saving or transferring the commercial documents, medical data, and every private picture. Nonetheless, the conventional encryption algorithms are usually focusing on the word message. These methods are too complicated or complex in the respect of image data because they have much more amounts of information to represent. In this sense, we proposed an efficient secret symmetric stream type encryption algorithm which is based on Boolean matrix operation and the characteristic of image data.

• 대한수학회지
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• 제33권2호
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• pp.367-379
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• 1996

Let $V = {(z, y) : f(z, y) = z^n + Ay^\alpha z^p + y^\beta z^q + y^k = 0}$ and $W = {(z, y) : g(z, y) = z^n + By^\gamma z^s + y^\delta z^t + y^k = 0}$ be germs of analytic irreducible subvarieties of a polydisc near the origin in $C^2$ with n < k and (n, k) = 1 where A and B are complex numbers. Assume that V and W are topologically equivalent near the origin.