• Journal of environmental and Sanitary engineering
• /
• v.22 no.4
• /
• pp.33-44
• /
• 2007

Since the introduction of a new field of skin care to Korean market which was developed in 1980, a variety of skin care therapies have appeared in mid-1990s. Therefore, in particular, it is considered that aroma therapy is one of the most preferred methods for skin care. Therefore, previous studies focused just on clinical effects of aromatherapy while this study focuses on aestheticians by identifying whether performance of aromatherapy, and their contribution to income will influence on satisfaction in aestheticians and customers' intention to reuse aromatherapy service for positive demonstration. The results of the study are presented as follows: First, it is demonstrated that side-effect of aromatherapy, contribution to income, and customer satisfaction have significant effect on professional aestheticians. In particular, in respect to the aestheticians, this study obtains the results rather different from the estimation that customers are satisfied with the professional service though they have side-effect. Second, as the satisfaction in professional aestheticians after skin care service is a significant factor that influences on intention to reuse it, this study concludes that re-management on behaviors is required according to the degrees of satisfaction.

• Proceedings of the Korean Association for Survey Research Conference
• /
• 2003.06a
• /
• pp.34-41
• /
• 2003

In many cases, the measurement error variances may be functions of the unknown true values or related covariates. This paper develops estimators of the parameters of a linear measurement error variance function based on wi thin-unit sample variaoces. This paper devotes to: (1) define measurement error scale factor $\delta$: (2) develop estimators of the parameters of the 1inear measurement error variance function under stratified multistage sampling design and small error conditions; (3) use propensity methods to adjust survey weights to account for possible selection effects at the replicate level. The proposed methods are applied to medical examination data from the U S Third National Health and Nutrition Examination Survey(NHANES III)

• IE interfaces
• /
• v.15 no.4
• /
• pp.444-451
• /
• 2002

Recently, the interest in technology valuation is revived and increasing mainly due to the lack of suitability of the traditional valuation methods in explaining the market reaction to newly-emerging knowledge-oriented companies. Moreover, many firms are now gearing their efforts to the strategic use of technology asset such as technology licensing, transfer and commercialization. Firms are also trying to enhance their technological competitiveness by re-evaluating their technology level and thus identifying the strengths/weaknesses of their technology portfolio. To accomplish this objective, the development of an integrated evaluation system for technology assets is essential. This paper presents a technology valuation system developed for a steel manufacturing company in South Korea. The valuation framework is based on; (1) the multi-attribute evaluation of technological competitiveness using Analytic Hierarchical Process and; (2) the expected future benefit of the technology using four different methods of discounted cash flow estimation. The suggested framework will be easily applicable to various industries where technological competitiveness should be evaluated systematically.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.9
• /
• pp.949-956
• /
• 2009

The C(t)-integral describes amplitude of stress and strain rate field near a tip of stationary crack under transient creep condition. Thus the C(t)-integral is a key parameter for the high-temperature crack assessment. Estimation formulae for C(t)-integral of the cracked component operating under mechanical load alone have been provided for decades. However, high temperature structures usually work under combined mechanical and thermal load. And no investigation has provided quantitative estimates for the C(t)-integral under combined mechanical and thermal load. In this study, 3-dimensional finite element analyses were conducted to calculate the C(t)-integral of elastic-creep material under combined mechanical and thermal load. As a result, redistribution time for the crack under combined mechanical and thermal load is re-defined through FE analyses to quantify the C(t)-integral. Estimates of C(t)-integral using this proposed redistribution time agree well with FE analyses results.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2002.10a
• /
• pp.237-240
• /
• 2002

Design rainfall using LH-moments following the consecutive duration were derived by the regional and at-site analysis using the observed and simulated data resulted from Monte Carlo techniques. RRMSE, RBIAS and RR in RRMSE for the design rainfall were computed and compared in the regional and at-site frequency analysis. Consequently, it was shown that the regional analysis can substantially more reduce the RRMSE, RBIAS and RR in RRMSE than at-site analysis in the prediction of design rainfall. RE for an optimal order of L-moments was also computed by the methods of L, L1, L2, L3 and L4-moments for GEV distribution. It was found that the method of L-moments is more effective than the others for getting optimal design rainfall according to the regions and consecutive durations in the regional frequency analysis. Diagrams for the design rainfall derived by the regional frequency analysis using L-moments were drawn according to the regions and consecutive durations by GIS techniques.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.1
• /
• pp.118-128
• /
• 2017

In this study, we propose a real time inertial navigation system/global positioning system (INS/GPS) integrated smoothing algorithm based on an extended Kalman filter (EKF) and a position damping loop (PDL) for synthetic aperture radar (SAR). Integrated navigation algorithms usually induce discontinuities due to error correction update by the Kalman filter, which are as detrimental to the performance of SAR as the relative position error. The proposed smoothing algorithm suppresses these discontinuities and also reduces the relative position error in real time. An EKF estimates the navigation errors and sensor biases, and all the errors except for the position error are corrected directly and instantly. A PDL activated during SAR operation period imposes damping effects on the position error estimates, where the estimated position error is corrected smoothly and gradually, which contributes to the real time smoothing and small relative position errors. The residual errors are re-estimated by the EKF to maintain the estimation performance and the stability of the overall loop. The performance improvements were confirmed by Monte Carlo simulations. The simulation results showed that the discontinuities were reduced by 99.8% and the relative position error by 48% compared with a conventional EKF without a smoothing loop, thereby satisfying the basic performance requirements for SAR operation. The proposed algorithm may be applicable to low cost SAR systems which use a conventional INS/GPS without changing their hardware configurations.

• Journal of Satellite, Information and Communications
• /
• v.3 no.1
• /
• pp.15-21
• /
• 2008

The high peak to average power ratio (PAPR) of OFDM (Orthogonal Frequency Division Multiplexing) system introduces inevitable non-linear distortion in the transmission due to the amplifier non-linear property. This causes both in-band distortion and out of band spectrum re-growth. In this paper we tried to compensate the problem by using polynomial based pre-distortion. Estimation of both the non-linear and inverse non-linear polynomial is achieved using the Least Square Error (LSE) method. Using these parameters closed form pre-distorter can be easily created. We also used the 'partial peak cancellation and clipping' method to remove the high peak present in the non constant amplitude of the OFDM signal responsible to drive the amplifier in near saturation region for better performance of the system

• Journal of Nutrition and Health
• /
• v.13 no.4
• /
• pp.159-166
• /
• 1980

Methods for the determination of sterols in sesame oils were studied. The sesame oils were saponified and the sterols isolated from the unsaponifiable matter by Florisil column chromatography, and the individual components were determined by means of gas chromatography. Campesterol, ${\beta}-sitosterol$, stigmasterol were found in sesame oil including unknown Ⅰ and Ⅱ. The use of SE-30 gas chromatographic column allows the slow elution, duplication of peaks and relatively low reproducibility, therefore, 3% OV-17 was suitable for the sterol analysis. The result of this study showed that contents of sterols in sesame oil were campesterol 8.4%, stigmasterol 4.5%, ${\beta}-sitosterol$ 33.9% and others 53.0% involving 8.8% of unknown I and 44.3% of unknown Ⅱ. There has been no specific test available for identifying the sesame oil among common edible oils. But the ratio of sterols in sesame oils allowed the estimation of genuiness. The ratio of sterols vs. campesterol in genuine sesame oils were stigmasterol 0.3- 0.6, ${\beta}-sitosterol$ 3.0-3.8 and unknown Ⅱ 3.0, respectively. The 65 samples were composed of genuine sesame oil 40%, mixed rape seed oil 3%, cotton seed oil 1. 5% others were reused soybean oil or re-extracted oil.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.12
• /
• pp.1220-1225
• /
• 2010

This paper proposes a novel active noise control (ANC) approach that uses an IIR filter and neural network techniques to effectively reduce interior noise. We construct a multiple-channel IIR filter module which is a linearly augmented framework with a generic IIR model to generate a primary control signal. A three-layer perceptron neural network is employed for establishing a secondary-path model to represent air channels among noise fields. Since the IIR module and neural network are connected in series, the output of an IIR filter is transferred forward to the neural model to generate a final ANC signal. A gradient descent optimization based learning algorithm is analytically derived for the optimal selection of the ANC parameter vectors. Moreover, re-estimation of partial parameter vectors in the ANC system is proposed for online learning. Lastly, we present the results of a numerical study to test our ANC methodology with realistic interior noise measurement obtained from Korean railway trains.

• Journal of Environmental Science International
• /
• v.12 no.8
• /
• pp.841-846
• /
• 2003

The ecosystem model was applied to estimate the regional distribution of the net production(or consumption) of phytoplankton and the net uptake(or regeneration) rate of nutrients in Masan Bay for scenario analysis to find a proper management plan. At the surface level, net production of phytoplankton is 200 mgC/㎡/day at the entrance of the bay, and 400∼1000 mgC/㎡/day at the center of the bay. The inner area of the bay showed more than 2000 mgC/㎡/day. All areas of the bottom level have a net consumption, with the center of the bottom level showing more than 600 mgC/㎡/day. For dissolved inorganic nitrogen, the results showed a net uptake rate of 100∼900 mg/㎡/day at the surface level. It showed that the net regeneration is above 50 mg/㎡/day at the bottom level. For dissolved inorganic phosphorus, the net uptake rate showed 10.0∼80.0 mg/㎡/day at the surface level, and the regeneration rate showed 0∼20.5 mg/㎡/day at the bottom level. Therefore, in order to control the water quality in Masan Bay, it is important to consider the re-supplement of nutrients regenerated in the water column.