• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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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).

• Journal of Korean Association for Spatial Structures
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• v.1 no.1 s.1
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• pp.125-134
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• 2001

The objective of this study is the development of size discrete optimum design algorithm which is based on the GAs(genetic algorithms). The algorithm can perform size discrete optimum designs of space trusses. The developed algorithm was implemented in a computer program. For the optimum design, the objective function is the weight of space trusses and the constraints are limite state design codes(1998) and displacements. The basic search method for the optimum design is the GAs. The algorithm is known to be very efficient for the discrete optimization. This study solves the problem by introducing the GAs. The GAs consists of genetic process and evolutionary process. The genetic process selects the next design points based on the survivability of the current design points. The evolutionary process evaluates the survivability of the design points selected from the genetic process. In the genetic process of the simple GAs, there are three basic operators: reproduction, cross-over, and mutation operators. The efficiency and validity of the developed discrete optimum design algorithm was verified by applying GAs to optimum design examples.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.70-79
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• 2012

A design guide to type-3 PLLs for FMCW radars is provided. To do that, the cross-over frequencies of the open-loop transfer functions were normalized to 1 Hz and closed-loop properties were compared through simulations using Pspice. As a result, several guides to design type-3 PLLs were provided: 1) secure 45 degrees of phase margin, 2) locate two zeroes at an identical frequency, and 3) poles may be added to raise order of the PLL at higher frequencies than the cross-over frequency of the open-loop transfer function about ten times.

• Journal of the Korean Society for Library and Information Science
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• v.31 no.3
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• pp.165-208
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• 1997

The purpose of this study is to evaluate the characteristics of user interface that affect the searching behavior of OPAC users. and then to propose how to design user-friendly interfaces of OPACS. An experiment was conducted on two systems with different interfaces to grasp the effect of user interface to search process and search outcome. A $2\times2$ cross-over design was used for the experiment. Sixty five searchers participated in the experiment. Several statistical techniques such as carry-over effect and system effect of a $2\times2$ cross-over design, $\chi^2$ test, t- test, McNemar test, test of marginal homogeneity through maximum likelihood method, factor analysis, regression analysis, and analysis of variance were applied according to the hypotheses tested and the data analyzed.

• The Korean Journal of Applied Statistics
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• v.14 no.2
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• pp.345-355
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• 2001

동일한 유효성분을 가지면서 용량 혹은 형식 만이 다른 제제의 개발이 증가되고 이에 따른 두 제제 이상의 생물학적 동등성시험의 필요성이 제기되었다. 이에 이용주 등(1998)은 온단세트론 제제에 대한 생물학적 동등시험에서 3$\times$3 교차설계법을 적용하였다. 그러나 3$\times$3 교차설계법에서 각 순서에 피험자의 수가 다르거나 실험중에 결락(dropout)되는 피험자가 발생하는 경우에는 일반적인 통계적 방법은 적용할 수 없었다. 본 연구에서는 이러한 경우에 제제효과의 추론에 대한 통계적 방법과 생물학적 동등성 시험 방법을 제안하고 모의실험을 통하여 생물학적 동등성평가의 정도를 측정하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.131-132
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• 2009

A road construction From Gyegok to Shinduk, korea was ordered for the alternative design by Jeollabuk-do, 2008. The propose of study is to introduce the planning process for a optimal eco-friendly design and construction of bridge cross over and parallel to rivers.

• Journal of Pharmaceutical Investigation
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• v.24 no.2
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• pp.49-55
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• 1994

Bioequivalence test of commercially available rifampicin capsules was performed. Sixteen volunteers were divided into 2 groups and the reference and test drug were given orally (450 mg) by cross-over design. Statistical evaluation of AUC, $C_{max}\;and\;T_{max}$ involved an analysis of variance (ANOVA). The differences of mean value in AUC, $C_{max}\;and\;T_{max}$ between the reference and test drug were within 20% with reference drug. ANOVA showed no significant differences for ‘between group’, ‘drug’ and ‘period’, but not for ‘between subjects’. The power of test $(1-{\beta})\;of\;AUC\;and\;$C_{max}$ was larger than 0.8 and the confidence of bioavailability was $within\;{\pm}20%$. From these results, it was concluded that the two preparations were bioequivalent for AUC and $C_{max}$, but was not for $T_{max}$.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1428-1434
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• 2004

This paper presents the mean streamline analysis using the empirical loss correlations for performance prediction of cross-flow fans. Comparison of overall performance predictions with test data of a cross-flow fan system with a simplified vortex wall scroll casing and with the published experimental characteristics for a cross-flow fan has been carried out to demonstrate the accuracy of the proposed method. Predicted performance curves by the present mean streamline analysis agree well with experimental data for two different cross-flow fans over the normal operating conditions. The prediction method presented herein can be used efficiently as a tool for the preliminary design and performance analysis of general-purpose cross-flow fans.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.184-189
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• 2004

This paper deals with design processing for TEDA-footbridge in Tianjin, China. The pedestrian cross over TEDA(Technology and Economy Development Area)-street as main street bridging both different areas in Tianjin. For resonable beautiful footbridge it need to technical mind and art. 'Science, not intuition, the tool of creativity' Starting with structure planning it need to cooperate both engineering and architect. We must solve a gaps between technology and art for structural design.

• Proceeding of KASS Symposium
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• 2005.05a
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• pp.83-88
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• 2005

This paper deals with design processing for in a east- north Seoul. The pedestrian cross over main street through Seoul and Uijongbu. For resonable beautiful footbridge it need to technical mind and art. The method of process for this footbridge approached in both the field of science and art. Starting with structure planning it need to cooperate both engineering and architect. To design a resonable and economical structural master piece, everyone must solve a gaps between technology and art for structural design.