• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.355-358
• /
• 2004

최근 웨이블릿 변환을 이용하여 저주파수 부대역 신호를 반복적으로 분해하고 삽입된 워터마크 비트에 따라 특정 부대역 신호에 두개의 다른 반향 중 하나를 삽입하는 반향 삽입 기법을 제안하였다. 이 기법은 오디오 신호의 주파수 특성을 고려했기 때문에 시간 영역에서의 기존의 반향 삽입 기법에 비해 비가청성(inaudibility), 워터마크의 강인성(robustness) 및 용적성(capacity)을 모두 증가시킬 수 있다. 기존의 부대역 신호 기반 반향 삽입 기법이 단일 반향 커널만을 이용하였으나, 본 논문에서는 부대역 신호에 다중 반향 커널을 이용한 반향 삽입 기법을 제안한다. 이 기법은 주관적 왜곡(perceptibility)과 SNR(signal to Noise Ratio)과 같은 객관적인 왜곡 면에서, 원본 오디오 신호의 왜곡을 줄일 수 있다. 실험 결과를 통하여 기존의 방법에 비해 제안된 방법이 SNR과 DR(Detection Rate) 모두 좋은 성능을 보여 제안된 방법의 유효성을 입증하였다.

• Journal of radiological science and technology
• /
• v.10 no.1
• /
• pp.31-35
• /
• 1987

Authors have investigated actual conditions of 22 hospitals throughout the Seoul district to evaluate of chest radiographic systems. The results are as followed: 1. Concerning exposure factors, most hospitals have used low tube voltage, merely two hospitals high tube voltage, that is, over 120 kVp. Roughly halves of intensifying screens have been used in hospitals were medium speed screens, and the rests were high speed screens. 2, Surface doses existed within wide range of $10{\sim}63.5mR$, and image quality value were $5.60{\sim}7.49$. 3. The minimum perceptibility of Burger Phantom have been increased with contrast improvement.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2004.10a
• /
• pp.521-524
• /
• 2004

Recently, acgis of authentication and crcator's copyright has become a matter of great concern by the diffusion of multimedia technique and the growth of the internet and the easily duplicated property of digital data. Consequently, many active researches have been made to protect copyright and to assure integrity by inserting watermark into the digital data. In this paper, watermark is repealed through the entire image and adapted to the content of the image. Achieved by an underlying process of transforming the digital image to the frequency domain by wavelet transform, which has three (vertical, horizontal, diagonal) directions and Multi-resolution features, and then choosing frequency area inferior to the human perceptibility and significant for invisible and robust watermark. We realize wavelet based image watermarking using Machine Vision of LabVIEW.

• Structural Engineering and Mechanics
• /
• v.74 no.5
• /
• pp.711-722
• /
• 2020

In this study, on-site testing was carried out to investigate the vibration serviceability of a composite steel-bar truss slab with steel girder system. Impulse excitations (heel-drop and jumping) and steady-state motion (walking and running) were performed to capture the primary vibration parameters (natural frequency and damping ratio) and distribution of peak acceleration. The composite floor possesses low frequency (<8.3Hz) and damping ratio (<2.47%). Based on experimental, theoretical, and numerical analyses on fundamental natural frequency, the boundary condition of SCSS (i.e., three edges simply supported and one edge clamped) is deemed more comparable substitutive for the investigated composite floor. Walking and running excitations by one person (single excitation) were considered to evaluate the vibration serviceability of the composite floor. The measured acceleration results show a satisfactory vibration perceptibility. For design convenience and safety, a crest factor β_rp describing the ratio of peak acceleration to root-mean-square acceleration induced from the walking and running excitations is proposed. The comparisons of the modal parameters determined by walking and running tests reveal the interaction effect between the human excitation and the composite floor.

• Journal of Families and Better Life
• /
• v.9 no.1 s.17
• /
• pp.95-112
• /
• 1991

This study is planned to provide the basic idea to seek for the appropriate Time Management Strategies and to investigate the Time Management Strategies and household work time of wives. For these research tasks, the data are collected through the questionnaire rand 479 respondents were housewives in seoul. Their data are analyzed using Frequency, ANOVA, Pearson's Correlation Analysis, Simple Regression Analysis, Multiple Regression Analysis. The Major findings of this study were as follows ; 1) There are significant differences in the time management strategies according to housewife's age, education level, and employment status, children's number, the type of housing, the type family, income and sex role attitude. 2) There are significant differences in the household work time according to housewife's age, education level, employment status, family size, children's number, type of housing, income, sex role attitude and time pressure perceptibility. 3) The Household work time is found to be negatively correlated to the Time Management Stategies except the adjustment of leisure and sleep time. 4) The Household work time is significantly related to housewife's employment status and the adjustment of leisure and sleep time.

• Structural Engineering and Mechanics
• /
• v.65 no.3
• /
• pp.349-357
• /
• 2018

An extensive research was undertaken to study the vibration serviceability of a long-span and light-weight floor subjected to human loading experimentally and numerically. Specifically, heel-drop test was first conducted to capture the floor's natural frequencies and damping ratios, followed by jumping and running tests to obtain the acceleration responses. In addition, numerical simulations considering walking excitation were performed to further evaluate the vibration performance of a multi-panel floor under different loading cases and walking rates. The floor is found to have a high frequency (11.67 Hz) and a low damping ratio (2.32%). The comparison of the test results with the published data from the 1997 AISC Design Guide 11 indicates that the floor exhibits satisfactory vibration perceptibility overall. The study results show that the peak acceleration is affected by the walking path, walking rate, and adjacent structure. A simpler loading case may be considered in design in place of a more complex one.

• Journal of Korea Multimedia Society
• /
• v.7 no.1
• /
• pp.98-105
• /
• 2004

In this paper, we proposed a watermarking algorithm for embedding visually recognizable pattern into the middle-frequency part:; of image. Binary image as watermark is embedded in the LH2, HL2 and HH2 band of wavelet transformed domain for copyright protection of image data. To evaluate robustness of the proposed method, we applied some basic algorithm of image processing such as scaling, filtering, cropping, histogram equalizing and lossy compression(JPEG, gif). As a result of experiment, the proposed method has the good image quality and the high perceptibility of watermark. It was demonstrated by experiments that the proposed algorithm can provide an excellent protection under various attacks.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.28 no.1
• /
• pp.37-46
• /
• 1998

The purpose of this study was to evaluate the diagnostic performance of the senior dental students for the proximal dental caries on intraoral radiographs and to compare it with the dental hospital residents, the reference group. It was also investigated the diagnostic performance according to the carious lesion depth. Thirty-five intraoral periapical and bitewing radiographs with 213 proximal surfaces included in this study were selected from the dental patients at Chonnam National University Hospital. The observers were 181 senior dental students from 5 dental schools and 40 dentists who were second year resident from 5 dental hospitals. They were asked to evaluate the presence or the absence of the proximal dental caries. The results were as follows: 1. The mean of the hitting rate for the overall observers was 184.51 surfaces and the diagnostic accuracy was 86.62％. 2. The diagnostic performance of the sound proximal tooth surfaces was very high, i.e., 91.5％ true negative rate and 8.5％ false positive rate. 3. The diagnostic performance of the dentist group was higher than the student group(P<0.05). 4. The proximal dental caries perceptibility increased as the lesion depth increased significantly(P<0.001) except no difference between the carious lesion depth III and IV (P>0.001).

• The Journal of Advanced Prosthodontics
• /
• v.5 no.3
• /
• pp.296-304
• /
• 2013

PURPOSE. The aim of this study was to evaluate the effect of polishing and glazing on the color and spectral distribution of monolithic zirconia. MATERIALS AND METHODS. Forty-five monolithic zirconia specimens ($16.3mm{\times}16.4mm{\times}2.0mm$) were fabricated and divided into 5 groups according to the number of A2-coloring liquid applications (Group I to V). Each group was divided into 3 subgroups according to the method of surface treatments (n=3): N: no treatment; P: polishing; G: glazing. Color and spectral distribution of five different areas of each specimen were measured according to CIELAB color space in the reflectance mode relative to the standard illuminant D65 on a reflection spectrophotometer. Data were analyzed using one-way ANOVA followed by Tukey's HSD test, Pearson correlation and regression analysis (${\alpha}$=.05). RESULTS. There was a significant difference in CIE $L^*$ between Subgroup N and P, and in CIE $b^*$ between Subgroup P and G in each group. Spectral reflectance generally decreased in Subgroup P and G in comparison with Subgroup N. Color differences between Subgroup P and G were within the perceptibility threshold (${\Delta}E{^*}_{ab}$ < 3.7) in most groups. Highly significant correlation was found between CIE $b^*$ and each subgroups as the number of coloring liquid applications increased ($R^2$ >0.88, P<.001). CONCLUSION. A perceptible color difference can be detected after polishing of monolithic zirconia. Polishing decreases the lightness, and glazing also decreases the lightness, but increases the yellowness of monolithic zirconia.

• Korean Institute of Interior Design Journal
• /
• v.22 no.5
• /
• pp.188-198
• /
• 2013

Advancement toward aging society has presented the importance of house planning in consideration of the elderly, increasing the necessity of such planning. Therefore the importance of indoor design guideline for elderly houses has been stressed and the understanding of the aging in regard to this trend will create more mature spaces. In line with this trend the purpose of this study is to study the medical factors related with bathroom interior design guidelines of the existing elderly houses from the viewpoint of deteriorating physical functions due to aging process. In order to research the deterioration of physical functions due to aging literatures of medical and exercise physiology were used and concerning the existing bathroom design guidelines for the aged people, the guideline items of behavior facilitation, physiological maintenance and perceptual maintenance aspects out of Murtha & Lee's user benefit criteria(1976) related with physical functions were selected to research in relation with the knowledge about the deterioration phenomena of physical functions. Physical aging and deterioration aspects were classified from the viewpoint of musculoskeletal disorder, cardiovascular disorder, respiratory disorder, gastronomy disorder, urology disorder, somatosensory disorder, endocrine disorder, immune disorder, nervous disorder and skin diseases and these were utilized in interpreting total 100 items of bathroom design guideline. Because bathroom is the space where many physical movements are done, it had the closest relationship with the deterioration of musculoskeletal health in general and as bathroom is the space where people use water and feel the difference in temperature and moisture more than other spaces, deterioration of skin and somatosensory health had the next closest relationship. The result of this study revealed that regarding the deterioration of physical functions of the elderly people in aspect of their perceptibility as designers will design creatively and sincerely based on its relationship with nervous system in future, the result of this study will be used to develop better spatial designs efficiently to meet for the aging society.