• Journal of Communications and Networks
• /
• v.7 no.3
• /
• pp.235-242
• /
• 2005

Multimedia applications and especially encoded video services, are expected to playa major role in the 3rd generation (3G) and beyond mobile communication systems. Given that future service providers are expected to provide video applications at various price and quality levels, quick and economically affordable methods for preparing/encoding the offering media at various qualities are necessary to be developed. This paper presents a method for objective evaluation of the perceived quality of MPEG­4 video content, based on a quantification of subjective assessments. Showing that subjectively derived perceived quality of service (PQoS) vs. bit rate curves can be successfully approximated by a group of exponential functions, the proposed method exploits a simple objective metric, which is obtained from the mean frame rate vs. bit rate curves of an encoded clip. The validity of this metric is assessed by comparing subjectively derived PQoS results to the corresponding ones, which come from the proposed objective method, showing that the proposed technique provides satisfactory PQoS estimation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.01a
• /
• pp.334-336
• /
• 2009

Estimation and correction of color temperature of digital images are basis of white balance adjustment after image acquisition stage. White balance is one of the most important image processing techniques for subjective image quality enhancement. Correction of color temperature is applied for white balance adjustment or for changing the mood of a picture. A picture taken under the daylight can be changed to have a mood of sunset or cloudy day, for example. We evaluate color temperature transformation of high dynamic range images in linear and log domain, and we conclude that linear domain transformation shows better results.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.01a
• /
• pp.1-6
• /
• 2009

Due to the different camera properties of the multi-view camera system, the color properties of captured images can be inconsistent. This inconsistency makes post-processing such as depth estimation, view synthesis and compression difficult. In this paper, the method to correct the different color properties of multi-view images is proposed. We utilize a gray gradient bar on a display device to extract the color sensitivity property of the camera and calculate a look-up table based on the sensitivity property. The colors in the target image are converted by mapping technique referring to the look-up table. Proposed algorithm shows the good subjective results and reduces the mean absolute error among the color values of multi-view images by 72% on average in experimental results.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.169-171
• /
• 2012

Although work-efficiency of construction machinery is a critical factor for estimating its workable-quantity per unit time, the coefficient figure table presented in the Poom-Sam that is used for Construction Cost Estimation of public sectors in Korea is very subjective for practical usage. In order to suggest objective work-coefficient table for a Tub Grinder, domestic and overseas documentary records were investigated and on-going construction sites were also visited. The research found that the table can be revised by means of detailing down by several factors. The research will be the foundation for applying the rapid development of Construction Equipment and technology to the appropriate cost estimations and the ground work of related studies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1260-1264
• /
• 2006

Shock-type vibrations are usually experienced in vehicles excited by impulsive forces. Fifteen subjects used magnitude estimation to judge the discomfort of vertical shock-type vibration generated on a rigid seat. The shocks had different frequencies and magnitudes and were produced from the response of a 1 degree-of-freedom model to a half-sine force input. The magnitudes of the shocks, expressed in terms of both peak-to-peak value and un-weighted vibration dose values, VDVs, were correlated with magnitude estimates of the discomfort. In this study, equivalent comfort contour of shock-type vibration were obtained. From the contour, it was investigated that shock-type vibration at frequency below 0.8 Hz and between 4.0 Hz and 10.0 Hz is highly sensitive to the discomfort than at other frequencies.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2002.11a
• /
• pp.153-156
• /
• 2002

본 연구는 스포츠웨어용 나일론 직물의 소리가 심한 소음으로 작용하여 착용자 뿐 만 아니라 상대방에게도 불쾌함을 주므로 이를 줄이기 위한 방향 모색의 하나로, 소리 자극에 대한 생리반응 중 근전도(Electrodiagnosis)와 소리에 대한 주관적 감성을 측정하여 의복 소음이 미치는 영향을 고찰하였다. 근전도는 상완이두근과 전완근에서 측정하였고, 주관적 평가는 FMME(Free Modulus Magnitude Estimation)를 이용하여 실시하였다. 직물 소리에 대한 상완이두근의 근전도 값은 직물별로 유의한 차이를 보였으나, 전완근에서는 대부분 비슷한 값을 보였다. 직물의 소리가 부드럽고 유쾌할수록 근전도값은 무자극시보다 감소하는 경향을 보였으나, 직물의 소리가 시끄럽고 날카로울수록 근전도값은 무자극시보다 증가하였다. 이로서, 직물의 소리는 상완이두근의 근전도 값에만 영향을 미치며, 직물 소음의 크기, 날카로움 등과 정적인 관계를 보이는 것을 볼 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.431-433
• /
• 2018

This paper proposes the system that offer super-wideband speech which is made by artificial bandwidth extension technique using wideband speech signal in time-domain. wideband excitation signal and line spectrum pair(LSP) are extracted based on source-filter model in time-domain. Two parameters are extended by each bandwidth extension algorithms, and then, super-wideband speech parameters are estimated. and synthesized. Subjective test shows super-wideband speech is better speech quality than wideband speech signal.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.4
• /
• pp.822-833
• /
• 1996

The video coding for very low bit rate has recently received considerable attention, but conventional block based transform coding schemes suffer from the blocking effect for the constraints of bit rates. In this paper, we present a video coding sysem suing multi-resolution motion estimation/compensation with variable size block(VMRME/C) and multi-resolution vector quantization(MRVQ) in wavelet transform domain for very low bit rate coding. It is shown that the presented scheme has better performance in the peak signal-to-nose ratio(RSNR) by 0.2-0.6 dB as well as subjective quality than that of conventional block based transform video coding techniques(especially, H. 263 which is DCT based video coding).

• Journal of Korean Institute of Industrial Engineers
• /
• v.24 no.3
• /
• pp.447-455
• /
• 1998

It is important to identify and evaluate poor working postures properly to prevent work-related musculoskeletal disorders. The purpose of this study is to develope a new upper body micropostural classification scheme for analyzing postural stress in industry. Most of the existing postural classification schemes were based either on the literature, or on simple biomechanical principles, or on a subjective ranking system. The scheme suggested in this study was based on perceived joint discomfort measured through experiment, in which nineteen subjects participated and the magnitude estimation method was employed to obtain subjects' joint discomfort. Also, the criteria for evaluating postural stress of working postures were presented for practitioners of health and safety to be able to redesign working methods and workplaces, which was based on maximum holding time by Miedema and other people. It is expected that the scheme developed in this study could be used as a valuable tool when evaluating working postures.

• The Journal of the Korean dental association
• /
• v.57 no.8
• /
• pp.448-455
• /
• 2019

This study aims to apply the Generalizability Theory (G-theory) for estimation of reliability of evaluation scores between raters on Patient Dentist Interaction. Selecting a number of raters as multiple error sources, this study was analyzed the error sources caused by relative magnitude of error variances of interaction between the factors and proceeded with D-study based on the results of G-study for optimal determination of measurement condition. The estimated outcomes of variance component for accuracy among the Patient Dentist Interaction evaluation with G-theory showed that impact of error was the biggest influence factor in students. The second influence was the item effect, and the rater effect was relatively small. The Generalizability coefficients for case1 and case2 which were estimated through the D- study were calculated relatively low.