• Proceedings of the Korea Inteligent Information System Society Conference
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• 2006.06a
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• pp.311-315
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• 2006

Viterbi decoder는 크게 BM(Branch metric), ACS(Add-Compare-Select), SM(Survivor Memory) block 으로 구성되어 있다. 이중 ACSU 부분은 고속 데이터 처리를 위한 bottleneck이 되어 왔으며, 이의 해결을 위한 많은 연구가 활발히 진행되어 왔다. look ahead technique은 ACSU를 M-step으로 처리하고 CS(Carry save) number를 사용한 새로운 비교 알고리즘을 제안하여 high throughput을 추구했으며, minimized method는 block processing 방식으로 forward, backward 방향으로 decoding을 수행하여 ACSU 부분의 feedback을 완전히 제거하여 exteremely high throughput 을 추구하고 있다. 이에 대해 look ahead technique 의 기본 PE(Processing Element)를 바탕으로 minimized method 알고 리즘의 core block 을 bit-level 로 구현하였으며 : code converter 를 이용하여 CS number 가운데 redundat number(l)를 제거하여 비교기를 더 간단히 하였다. SYNOPSYS의 Design compiler 와 TSMC 0.18 um library 를 이용하여 합성하였다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.82-85
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• 2000

In cold forging, the final product is usually given by multi-stage process and the preform with stepped shape can be manufactured through the various forging method. The forward extrusion and upsetting processes for preform with stepped shape have been analyzed by using the rigid-plastic finite element analysis code, InteFORM and compared for load and stroke according to ae reduction of weを An engineer should select the proper processes considering the capacity and the stroke of the corresponding press in the forging of the preform with stepped shape.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.404-414
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• 2013

In the conceptual design phase of jet fighters, the trade study is performed repeatedly for a selection of the baseline configuration. The automation of repeated trade study makes possible to select efficiently the baseline configuration. In this study, the performance analysis code was developed for the automation of trade study. The code was consists of the module of shape generation, the module of weight estimation, the module of mission performance analysis. 3D CAD Model can be generated by the module of shape generation and Weight can be estimated by using the empirical equation in the module of weight estimation. The module of mission performance analysis was able to calculate the mission performance about the arbitrary mission profile. In addition, the optimal mission performance can be calculated by using optimization method. By performing the validation, the code was confirmed to be able to apply to the conceptual design phase.

• Fashion & Textile Research Journal
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• v.16 no.5
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• pp.766-775
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• 2014

This study is aimed to research the actual wearing condition of ballet dancewear of girls aged between 2 and 6 years on its design, size and fit. Survey data were collected from 171 mothers who have a girl learning ballet dance. The questionnaire was composed with ballet education, ballet dancewear purchasing, preference on design, size selection, and fitting. The collected data were analyzed with frequencies statistics, ${\chi}^2$-test, ANOVA using the SPSS WIN 20.0. The results are as follows; High rate of respondents said that the purpose of ballet education was for good body balance, leisure activity, and height growth. The main method of purchase was online shopping. The design, price, size and fit were identified as important ballet dancewear attributes for girls. The most preferred style of ballet dancewear were 'short sleeve skirted leotard' and 'camisole skirted leotard' which look like dress. The respondents reported slight satisfaction with size and fit, price, convenience in action, sewing and durability. The most preferred sizing system was code by height but any ballet dancewear makers don't use code by height. Therefore it is difficult for consumers to select size. Retailers and manufacturers could potentially use the results of this study to improve the sizing system and fit for children's ballet dancewear.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.2
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• pp.159-165
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• 2024

The Global Navigation Satellite System (GNSS) has been used as a tool to accurately extract the Total Electron Content (TEC) in the ionosphere. The multi-GNSS (GPS, GLONASS, BeiDou, Galileo, and QZSS) constellations bring new opportunities for ionospheric research. In this study, we develop a regional ionospheric TEC model using GPS, Galileo, and QZSS measurements. To develop an ionospheric model covering the Asia-Oceania region, we select 13 International GNSS Service (IGS) stations. The ionospheric model applies the spherical harmonic expansion method and has a spatial resolution of 2.5°×2.5° and a temporal resolution of one hour. GPS TEC, Galileo TEC, and QZSS TEC are investigated from January 1 to January 31, 2024. Different TEC values are in good agreement with each other. In addition, we compare the QZSS(J07) TEC and the Center for Orbit Determination in Europe (CODE) Global Ionosphere Map (GIM) TEC. The results show that the QZSS TEC estimated in the study coincides closely with the CODE GIM TEC.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.61-74
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• 2005

Digital Multimedia Broadcasting(DMB) is a reliable multi-service system for reception by mobile and portable receivers. DMB system allows interference-free reception under the conditions of multipath propagation and transmission errors using COFDM modulation scheme, simultaneously, needs powerful channel error's correction ability. Viterbi Decoder for DMB receiver uses punctured convolutional code and needs lots of computations for real-time operation. So, it is desired to design a high speed and low-power hardware scheme for Viterbi decoder. This paper proposes a combined add-compare-select(ACS) and path metric normalization(PMN) unit for computation power. The proposed PMN architecture reduces the problem of the critical path by applying fixed value for selection algorithm due to the comparison tree which has a weak point from structure with the high-speed operation. The proposed ACS uses the decomposition and the pre-computation technique for reducing the complicated degree of the adder, the comparator and multiplexer. According to a simulation result, reduction of area $3.78\%$, power consumption $12.22\%$, maximum gate delay $23.80\%$ occurred from punctured viterbi decoder for DMB system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.220-223
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• 2001

Until now, the clamp yoke of automobile has been largely manufactured by hot forging or burring process. Through the study, the precision cold forging process for clamp yoke has been analysed by using rigid-plastic finite element analysis code, DEFORM-3D. It has shown various results of the FEM simulation. An engineer should select the proper process considering the amount of product.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.90-96
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• 2009

In this study, a generic airfoil designed by the inverse method was evaluated with several candidate airfoils as a first step. Each airfoil was compared with respect to aerodynamic performance to meet the requirement of HALE(high altitude long endurance) aircraft. The second step was to optimize the candidate airfoil using the couple of optimization formulations to down select an optimum airfoil. For the analysis of low Reynolds number 2D flow, Drela's MSES was used. After comparing the aerodynamic results, the best airfoil was chosen to construct the baseline 3D wing. The Navier-Stokes code was used to evaluate the overall aerodynamic performance of designed wing with other wings. The results show that the designed wing has the best performance compared with other wings.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1990.04a
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• pp.42-48
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• 1990

Increasing concerns about model management system lead to studies of user friendliness and model executions. This paper presents model as object's method based on the Object-Oriented Concepts which makes it possible to represent model's operation and enables general decision makers to identify and select more appropriate models. This capability reduces the semantic gap between decision maker and model builder. This view is also able to execute models by way of automatic Ada code generation and specific LP formulation for LINDO. A prototype system is implemented in Pascal.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.4
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• pp.134-139
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• 1984

This paper presents the computer program to design the synchronous sequential logic circuit. The computer program uses the MASK method to get the circuit of optimal cost. The computer program takes as an input, the minimal reduced state transition table where each state has its internal code. As an output,the optimal design of synchronous sequential logic circuit is generated for each flipflop type of JK,T,D, and RS respectively. And these circuits for 4 flipflop types are evaluated and sorted in ascending order of their costs, so that the user can select the proper flipflop type and its circuit. Furthermore,the proposed computer program may be applied to state assignment with its facility of cost evaluation.