• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.96-106
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• 2009

In this paper, correlation between the headphone's acoustical characteristics and the subjective preferences is analyzed, and a possibility of predicting the subjective preferences using the acoustical characteristics is investigated, The headphone's acoustical characteristics include the total harmonic distortions, the variation of the frequency response which were measured by separate channel and the inter-aural correlation coefficients, Those characteristics were measured in a noise-free anechoic chamber, using a head and torso simulator, The subjective preferences were scored in terms of loudness, clearness, spaciousness, fullness and overall impression, In the subjective listening test, 12 subjects were participated who have plentiful listening experiences, The programs include 5 kinds of musics; korean popular song, pop song, light music, male-voice and classic, The 8 models of the headphones were employed, including 4 closed-type circumaural headphones, 2 open-type supraaural headphones and 2 intra-concha headphones, A significant test was carred on the results from the subjective test, using a two-way ANOVA test, The correlation coefficients between the acoustical parameters and the subjective preferences were computed, Experimental results showed that the variation of the magnitude of frequency response measured from a right channel revealed higher correlation with the subjective preferences. Whereas the inter-aural correlation coefficients have very low correlation coefficients.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.1
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• pp.40-47
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• 2015

Dynamic response of any small structure is always affected by the mass of the attached accelerometer. This paper predicts the natural frequencies and frequency response functions by removing the mass loading effect from the accelerometer. This mass loading is studied on a simple cantilever beams by varying the location of accelerometer. By using sensitivity analysis with iteration method, accelerometer mass and location are obtained. The predicted natural frequencies of the small cantilever beam without the accelerometer's mass show good agreement with the structural re-analysis.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1648-1653
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• 2003

This paper predicts the modified proportional damping structural eigenvectors and eigenvalues due to the change in the mass and stiffness of a proportional damping structure by iterative calculation of the sensitivity coefficient using the original dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom lumped mass model by modifing the mass and stiffness. The predicted dynamic characteristics are in good agreement with these from the structural reanalysis using the modified mass and stiffness.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.786-791
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• 2004

This study proposed the analysis of mass position detection and modified stiffness due to the change of the mass and stiffness of structure by using the original and modified dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom by modifying the mass. The predicted detection of mass positions and magnitudes are in good agreement with these from the structural reanalysis using the modified mass.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1388-1398
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• 2000

A pipe prover is a flowmeter calibrator used in flow measurement field. Gravimetric and volumetric methods were applied to determine the basic volume of the pipe prover. Uncertainty of its basic volume measurement was evaluated in accordance with the procedure recommended by International Organization for Standardization. The combined standard uncertainty of determining the basic volume was estimated from the sensitivity coefficient and the standard uncertainty of independent variables. It was found that the uncertainties of the weighing and volume measurements have dominant influence on that of the basic volume determination. With the quantitative analysis of the sensitivity coefficient, the contribution of the each variable uncertainty to the combined standard uncertainty of the basic volume is shown clearly.

• Journal of Energy Engineering
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• v.11 no.4
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• pp.291-298
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• 2002

This paper presents a practical methodology that can analysis power flow and marginal factors based on optimal power flow (OPF) of power systems under restructuring environment. First of all, to evaluate useful marginal factors, nonlinear optimization problems of minimum fuel cost and minimum transmission loss are formulated and solved by nonlinear primal-dual interior point method. Here, physical constraints considered in the optimization problems are the limits of bus voltage. line overloading, and real & reactive power generation. Also, an evaluation method of marginal price and marginal transmission loss is presented based on sensitivities calculated by the two OPF problems. Especially, to reflect the cost related to transmission losses in the competitive electricity market, an analysis method of MLF (marginal loss factor) is pro-posed. Numerical results on IEEE RTS 24 show that the proposed algorithm is effective and useful for analysis of power market price.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1333-1337
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• 1987

본 연구는 머리운동 제어 시스템에 대한 생체 물리학적인 모델링과 시뮬레이션을 통하여 모델의 동특성을 조사하였으며, 생체운동(머리-안구)의 상호 관계를 비교하였다. 결과를 요약하면 다음과 같다. 1) 시스템을 구성하고 있는 매개변수의 변화가 출력에 미치는 영향을 조사하기 위해 감도해석법을 써서 감도계수를 구한 결과, 입력 제어신호의 펄스높이(PH), 동근의 펄스폭(PW1), 길항근의 펄스폭(PW2)이, 시스템의 출력특성을 결정하는 가장 중요한 매개변수 임을 알 수 있었다. 2) 비 선형 제어모델의 선형화를 통하여 선형모델의 응답특성과 크나큰 차이가 없음을 알았다. 3) Main-Sequence도를 작성하여 실험 데이터와 비교한 결과, 거의 일치함으로서 모델의 타당성을 입증하였다. 4) 머리운동이 시간최적으로 응답하기 위해서는 bang-bang 제어법칙이 적용되어야 함을 알았다. 5) 머리운동이 목표점에 도달하는 순간에는 길항근의 역제통 펄스가 가해 짐으로서, 길항근이 궤적의 마지막 부분을 지배함을 알았다. 6) 머리-안구운동의 main-sequence도를 비교 함으로서 상호관계를 규명하였다. 앞으로는 이 모델링 법을 개선확장하면, 비행시 파일럿의 생체 시뮬레이션, 헬멧 조준 사격 시스템등의 항공공학, 생체의용공학 연구 및 제어입력을 생체신호로 하는 로봇틱스 연구에 본 연구 방법은 유용하리라 생각된다.

• Journal of Power System Engineering
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• v.5 no.4
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• pp.82-89
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• 2001

To design a structural or a mechanical system with the best performance, the main procedure of a typical design usually consists of repeated modifications of design parameters and the investigation of the system response for each set of these parameters. But this procedure requires much time, effort and experience. Sensitivity analysis can provide systematic information for improving performance of a system. The author has studied on the development of the structural analysis algorithm and suggested recently the transfer stiffness coefficient method(TSCM). This method is very suitable algorithm to a personal computer because the concept of the TSCM is based on the transfer of the nodal stiffness coefficients which are related to force and displacement vectors at each node. In this paper, a new sensitivity analysis algorithm using the concept of the TSCM is formulated for the computation of state variable sensitivity in static problems. The trust of the proposed algorithm is confirmed through the comparison with the computation results using existent sensitivity analysis algorithm and reanalysis for computation models.

• Analytical Science and Technology
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• v.8 no.3
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• pp.359-364
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• 1995

Urinary dipeptidase(Udpase) was assayed by fluorometric analysis of NADH which was produced from an indicator enzyme, L-alanine dehydrogenase. The reaction mixture was consisted of a dipeptide(L-ala-L-ala), ${\beta}-NAD^+$, L-alanine dehydrogenase in 12.5 mM sodium carbonate buffer, pH 9.0, and urinary dipeptidase which initiated the reaction. The fluorescence intensity of NADH was measured as a function of time with the excitation wavelength at 340nm and emission at 460nm. Comparison of this fluorometric method with the conventional spectrophotometric method utilizing glycyldehydrophenylalanine(Gdp) as substrate provided the correlation coefficient of 0.996 and increased the sensitivity more than ten times.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.20-25
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• 1998

This paper presents an algorithm for contingency ranking using line outage distribution factors(LODF) which are established by generation shift distribution factors(GSDF) from DC load flow solutions. By using the LODF, the line flow can be calculated according to the modification of base load flow if the contingency occur. To obtain faster contingency ranking, only the loading line more than 35[%](60[%] at 154[kV]) is included in the computation of Performance Index(PI). The proposed algorithm has been validated in tests on a 6-bus test system.system.