• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.187-187
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• 2017

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.67-68
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• 2009

This research aims at investigating the seismic behavior of RC bridge piers subjected to NFGM in low or moderate seismic region according to Volumetric Confinement Steel Ratio through the shaking table test unlike original way of the test. This investigation deal with the estimate with SARCF for shaking table test by the comparative analysis for the value of FFT.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.1-10
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• 2003

An airship is statically unstable, because it has no wing, comparatively small tail and large hull. Hence, an accurate prediction of dynamic stability is critical. In this study, dynamic stability data of the Mid-Size Airship is acquired through forced oscillation wind tests. The test was done in BAR LAMP which is Birhle Applied Research Inc's facility located in Germany. The test was composed with 16 static runs and 26 dynamic runs. As a result, dynamic characteristics of the airship depends on sideslip angle, angular rate and its direction as well as angle of attack. Generally, it is obtained that 3 directional moments have damping, but normal force, side force, and cross-derivatives are unstable. The dynamic derivatives are not sensitive to control surfaces, but have nonlinear dependency on sideslip angle.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.965-971
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• 2017

The primary objective of this study was to assess the energy efficiency performance of an optimized hull form capable of saving energy based on existing vessels. The bow shape of existing vessels was investigated, giving consideration to design draft and speed. Resistance performances were also assessed for existing vessels according to operating conditions. Commercial CFD codes and model test materials were used to assess effective power. An optimized hull form with minimum resistance was selected given real operating conditions. The effective horsepower of existing and optimized vessels was estimated at three speeds. Resistance performance for an optimized vessel showed a 6 % improvement in effective horsepower at design speed (12 knots) compared to existing vessels. Quasi-propulsive efficiency employed experimental data, while energy efficiency performance was analyzed based on operating days, bunker fuel oil C cost, daily fuel oil consumption and specific fuel oil consumption. Energy efficiency performance for an optimized vessel showed a gain of 30 million won per year in reduced costs at design speed (12 knots) compared to existing vessels.

• Journal of the Korean Geotechnical Society
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• v.22 no.1
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• pp.35-44
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• 2006

In general typically granular soils contain a certain amount of fines. It is also widely recognized that foundation soils under working loads show highly non-linear behavior from very early stages of loading. In the present study, a series of laboratory tests with sands of different silt contents are conducted and methods to assess strength and stiffiness characteristics are proposed. Modified hyperbolic stress-strain model is used to analyze non-linearity of silty sands in terms of non-linear Degradation parameters f and g as a function of silt contents and Relative density Dr. Stress-strain curves were obtained from a series of triaxial tests on sands containing different amounts of silt. Initial shear modulus, which is used to normalize Degradation modulus of silty sands, was determined from resonant column test results. From the laboratory test results, it was observed that, as the Relative density increases, values of f decrease and those of g increase. In addition, it was found that values of f and g increase and decrease respectively as a Skeleton void ratio $(e_{sk})$ increases.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.183-194
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• 2004

It's essential process to study non-linear material function related to characteristics of compressibility and permeability when we predict the consolidation behavior of soft clay ground. In this study, laboratory tests were conducted to find out the material function using marine clay. Standard oedometer test and Rowe cell test were performed with conditions, which were classified into vertical drainage only, radial drainage only and vertical-radial drainage case. Modified oedometer test equipment was developed to find out the material function and special extrusion device was originated to minimize the sample disturbance effect. Reliability of the results in modified oedometer test could be confirmed by comparing with the Rowe cell's one. Effective stress - void ratio - permeability relations were analyzed using all testing results. As a result, void ratio with effective stress level could be expressed by the power function and permeability with void ratio could be expressed by exponential function. In soft clay with high initial water content and low shear strength, non-linear characteristics related to compressibility and permeability varied with wide range by the effective stress levels. It's important to note that non-linearity of the material function should be considered at prediction of the consolidation behavior.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.97-104
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• 1996

DYGABCD 프로그램을 이용해 선형모델의 구성에 필요한 시스템 행렬을 구하고 최소자승법을 이용하여 실시간 선형모사를 행한 후 DYNGEN 프로그램을 이용한 비선형 모사와 비교하여 그 타당성을 입증하였다. 그리고 가제어성과 가안정성을 시험하여 시스템에 대해 제어기설계가 가능한지 확인하고 엔진의 성능과 직결되는 터빈입구 온도의 Overshoot 제어를 위해 고전적 제어기법인 PI제어기와 현대적 최적제어기법인 LQR 제어기를 설계하여 각각의 성능을 비교해 보았다.

• Journal of Korea Ship Safrty Technology Authority
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• v.16
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• pp.38-52
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• 2004

쌍동선이나 삼동선과 같은 다동체를 가진 선박의 선형과 유체 동력학적 특징들에 대하여는 실험과 동시에 수치적으로 널리 연구되어 왔다. 본 연구는 소형 다동체 레저낚시어선의 선형개발에 관한 연구로서 모형실험은 인하대학교 선형시험구조에서 수행되었으며 수치계산은 Euler 방정식의 유한차분해법이 이용되었다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.19-21
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• 2007

우리나라 조선산업은 생산성 향상을 통한 건조척수의 증가를 통하여 일본과 더불어 세계 $1^{\sim}2$위의 시장 점유율을 기록하는 등 세계 최고의 수준이다. 그러나 국내 중소형 조선소나 조선기자재업체의 경우에는 기술 인력의 부족으로 인하여 독자적인 기술의 확보와 기술개발 여건이 마련되어 있지 않은 상황이다. 특히, 구명정(Life boat)은 선박의 비상 탈출 장비로써 법적으로 의무 설치가 강제화 되어 있는 선박 안전에 있어 필수적인 장비로서 수요도 꾸준히 증가하고 있으나, 국내의 구명정 제작업체로는 현대라이프보트가 유일하며 2004년 기준 국내 신조선박에 탑재되는 수량의 25%, 세계시장의 4% 만을 공급하고 있다. 이외의 수량은 $7^{\sim}8$ 개의 유럽 등 외국업체와 중국업체들이 제작, 공급하는 실정이다. 이에, 본 연구에서는 구명정의 신선형 개발과 선형시험 통한 성능 검증 및 품질 향상과 풍수절감을 위한 생산성 향상 방안, 기존 몰드 개선 방안 연구 등을 수행하고 시제선을 건조하여 저가의 외국 구명정에 대응하여 국내 구명정 기술 경쟁력을 향상시킬 수 있는 전폐형 구명정의 국산화를 달성하였다.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.361-369
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• 2015

A general linear mixed-effects model is often used to analyze repeated measurement experiment data of a continuous response variable. However, a general linear mixed-effects model can give improper analysis results when simultaneously detecting heteroscedasticity and the non-normality of population distribution. To achieve a more robust estimation, we used a heavy-tailed linear mixed-effects model for a more exact and reliable analysis conclusion than a general linear mixed-effects model. We also provide reliability analysis results for further research.