• 한국항공우주학회지
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• 제46권1호
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• pp.32-40
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• 2018

본 논문에서는 개념설계 단계에서 주로 사용되는 통계적 중량 예측식 도출 방법에 관한 연구를 수행하였으며 Microsoft Excel을 이용해 이를 프로그램화하고 제트 여객기에 적용하여 검증하였다. 기존 중량 예측식들의 변수들을 참고하여 데이터베이스를 구축하였고 이를 사용하여 제트 여객기 날개 중량 예측식을 모델링하였다. 모델의 과적합 문제를 해결하기 위해 K-fold cross validation 방법을 사용하여 모델을 평가하였다.

• 수산해양기술연구
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• 제56권4호
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• pp.374-383
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• 2020

At ship design stage, the maneuverability is generally estimated based on the empirical formula or the computational fluid dynamic (CFD), which is one of the numerical simulation methods. Using the hydrodynamic derivatives derived through these methods can quantitatively estimate the maneuverability of target vessels and evaluate indirect maneuverability. Nevertheless, research on estimating maneuverability is insufficient for ships not subject to IMO maneuverability standard, especially fishing vessels, and even at the design stage, the empirical formula developed for merchant ships is applied without modification. An estimation error may occur due to the empirical formula derived from the regression analysis results of a model test if the empirical formula developed for merchant ships with different hull shapes is applied to fishing vessels without any modification. In this study, the modified empirical formula that can more accurately estimate the fishing vessel's maneuverability was derived by including the hull shape parameter of target fishing trawlers in the regression analysis process that derives Kijima et al. (1990) formula. As a result, the modified empirical formula showed an average estimation error of 6%, and the result improved the average error of 49% of Kijima et al. (1990) formula developed for merchant ships.

• 한국의류학회지
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• 제35권11호
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• pp.1271-1284
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• 2011

This study improves the fitness of Air Force winter service uniforms through the development of a shirt pattern drafting method and automatic pattern drafting program for MTM production. A calculation formula is formed through a correlation analysis and regression analysis using Size Korea 2004 3D measurement data after analyzing 4 kinds of existing shirt pattern drafting methods and 3 types of shirt patterns currently used for the Air Force service uniform. The results of this study are as follows: The developed pattern drafting method has 4 parts that use calculated dimensions: neck base width, front interscye, back interscye and scye depth. Other body measuring parts that have a high correlation with calculation parts are inserted into regression analysis as independent variables to create dimension calculation formulas. The result of the final study patterns were better than existing winter service uniforms in nearly all items for the appearance evaluation and motion adaptability evaluations. The method was converted into an automatic pattern drafting program using C++ after the completion of pattern drafting method development.

• 한국공간구조학회논문집
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• 제14권1호
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• pp.61-68
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• 2014

The design of foot-bridge is often influenced by natural frequency. Consequently, vibration frequency becomes important. The empirical expressions used to quantify this parameter at the design phase have not been developed enough to give guideline to Korean foot-bridge. This paper is concerned with the vertical natural frequency of steel foot-bridges. It describes the vibration measurement methods employed for testing structures and presents reliable methods of assessing natural frequency from jumping vibration tests. Data from measurements on 16 structures in Seoul are given. Regression formulas of natural frequency for steel-framed foot-bridges are suggested. Finally, obtained formula are compared with empirical expressions of Seoul City's guideline.

• The Korean Journal of Ecology
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• 제14권4호
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• pp.361-370
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• 1991

The cone and seed production of pitch pine were investigated at two areas(songtan and yangdong) located in kyounggi province. Bymeans of formulas derived from both the regression analysis between the number of seeds and cone length, and between d2·h and number of cones, cone and seed production were estimated. The correlation coefficient value between the number of seeds and cone length was high(r=0.6134). The cone and seed production of pitch pine has a high relationship to the variables-dbh, tree aga , and height of tree. The cone production of pitchpine forest estimated by the formula log(o+s+y+c)=0.581 log(d2·h)-1.317 was 965,832/ha in 1985∼1986, 850,852/ha in 1986∼1987 at songtan, and 462,794/ha in 1985∼1986,916,965/ha in 1986∼1987 at yangdong.

• Structural Engineering and Mechanics
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• 제36권2호
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• pp.225-241
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• 2010

In this study, a hybrid search algorithm combining genetic programming with orthogonal least squares (GP/OLS) is utilized to generate prediction models for compressive strength of high performance concrete (HPC) mixes. The GP/OLS models are developed based on a comprehensive database containing 1133 experimental test results obtained from previously published papers. A multiple least squares regression (LSR) analysis is performed to benchmark the GP/OLS models. A subsequent parametric study is carried out to verify the validity of the models. The results indicate that the proposed models are effectively capable of evaluating the compressive strength of HPC mixes. The derived formulas are very simple, straightforward and provide an analysis tool accessible to practicing engineers.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.371-376
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• 1998

In this study, the size effect of concrete members subjected to the axial load and bending moment is investigated using a series of C-shaped specimens of which test procedure is similar to those of Hognestad, Hanson, and McHenry's. Main test variable is a size ratio of the specimens(1:1/2:1/4) at the concrete compressive strength of 500kg/㎠. Test results show that the flexural compression strength at failure decreases as the size of specimen increases, that is, the size effect law is present. Model equation is derived using regression analyses with experimental data and it is compared with formulas for compressive strength of cylinders and shear strength of beams without stirrups. Size effects is distinct th following sequence; shear strength of beams without stirrups, compressive strength of C-shaped specimens, compressive strength of cylinders.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.149-154
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• 2001

Ship owners are demanding quieter vessels since crews have become more sensitive to their acoustic environment. Accordingly, designers of shipyards need to respond intelligently to the challenging requirements of delivering a quiet vessel. In early design stage, to predict shipboard noise the statistical approach is preferred to other methods because of simplicity. However, since the noise characteristics of the ships vary continuously with the environments, it is necessary to update the prediction formula with data base management system. This paper describes the feature of database program with the prediction method. Database management programs with GUI, are applied to Intranet system that is accessible by any users. Statistical approach to the prediction of A-weighted noise level in ship cabins, based on multiple regression analysis, is conducted. The noise levels in ship cabins are mainly affected by the parameters of the deadweight, the type of ship, the relative location of engines and cabins, the type of deckhouse, etc. As a result of verification, the formulas ensure the accuracy of 3 ㏈ in 83 % of cabins.

• Ocean Systems Engineering
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• 제4권2호
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• pp.151-167
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• 2014

It is common that analyses of offshore platforms being carried out with the assumption of rigid tubular joints. However, many researches have concluded that it is necessary that local joint flexibility (LJF) of tubular joints should be taken into account. Meanwhile, advanced analysis of old offshore platforms considering local joint flexibility leads to more accurate results. This paper presents an extensive finite-element (FE) based study on the flexibility of uni-planner multi-brace tubular Y-T and K-joints commonly found in offshore platforms. A wide range of geometric parameters of Y-T and K-joints in offshore practice is covered to generate reliable parametric equations for flexibility matrices. The formulas are obtained by non-linear regression analyses on the database. The proposed equations are verified against existing analytical and experimental formulations. The equations can be used reliably in global analyses of offshore structures to account for the LJF effects on overall behavior of the structure.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 1997년도 한국감성과학회 연차학술대회논문집
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• pp.57-62
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• 1997

The purposse of this study is to evaluate the effect of mechanical properties on handle of fabrics for some of the korean women's clothes, 160 different kinds of commercial silk and polyester fabrics were used for this study. Mechanical properties were measured by the KES-FB fabric testing systems and six hand judgements. and also, the technique of stepwise-block-regression method was applied to investigate relationship between sensory and mechanical properties. Finally, we have obtained useful formulas for calculation the hand valuer of fabrics for korean clothes.