• The Journal of the Acoustical Society of Korea
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• v.22 no.1
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• pp.7-13
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• 2003

Numerous investigations have demonstrated that diffused reflection is one of the most important factors in predicting room acoustics by computer simulation. Recent studies have suggested several computational algorithms in order to account for diffused reflections in the ray tracing or beam tracing method. In this study, a computational algorithm for the calculation of diffuse sound reflections in the image method is suggested and a computer simulation system is developed based on the suggested algorithm. The methodology adopted in our computer simulation system is similar to the extended radiosity method, which is developed for the computer graphics. In a real room, sound energy is reflected in a partially diffused manner which results in four reflection combinations: diffuse-diffuse, specular-specular, diffuse-specular and specular-diffuse. In this study, higher order form factor is introduced to handle the four types of reflection combinations so that the partially diffused reflection could be modeled. In this paper, the concept of extended radiosity method is described and the approximate method of calculating higher order form factor is suggested. Finally, the effect of higher order form factors on the simulation of reverberation time is investigated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.190-199
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• 2019

This study was conducted to expand the distribution of new technology efficiently by analyzing the structure relationship based on the innovation resistance model and partial least square structural equation model (PLS-SEM). This study selected innovative propensity, relative advantage, compatibility, complexity, trialability, risk, and extension service consisting of educational, technical, and funding services as factors affecting innovation resistance. This study constructed a questionnaire that measured 11 factors including acceptance intention of new technology using 33 indicators. Data was from April to October, 2017, targeting 180 farmers who did not join in projects to spread new technologies of the Rural Development Administration. Results showed the factors positively and significantly affecting innovation resistance include complexity and risk. Innovative propensity did not have any effect on innovation resistance. However, it positively affected acceptance intention of new technology. The service of the extension organizations had a negative effect on innovation resistance, but did not affect acceptance intention of new technology. This study suggests that extension services should promote activities such as education, consulting, publicity and pilot projects related with new technologies in order to minimize the antipathy toward new agricultural technologies.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.307-313
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• 2018

In this study, analyzed the effect of the introduction and operation of internal control system of a company on accounting information usefulness in a rapidly changing business environment. In order to conduct this study, we studied a comprehensive analysis on the usefulness of internal control and accounting information, and applied the research model to the purpose of this study. In this study, we analyzed the degree of the relationship between variables based on the discretionary accruals of the modified Jones model using the internal control evaluation index based on the components of the internal control system for China. In the empirical analysis, analyzed that the operation of internal control has a negative influence on discretionary accruals, which is a substitute for usability of accounting information. In addition, the risk management factors of the internal control system have a negative correlation with the usefulness of accounting information. The results of this study suggest that it is possible to present the positive function of internal control system to many firms where the introduction and operation of internal control is important, and to provide useful guidance in the study of the relationship between the operation of internal control and discretionary accruals for foreign company.

• Journal of Intelligence and Information Systems
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• v.22 no.1
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• pp.43-61
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• 2016

Customer reviews help potential customers make purchasing decisions. However, the prevalence of reviews on websites push the customer to sift through them and change the focus from a mere search to identifying which of the available reviews are valuable and useful for the purchasing decision at hand. To identify useful reviews, websites have developed different mechanisms to give customers options when evaluating existing reviews. Websites allow users to rate the usefulness of a customer review as helpful or not. Amazon.com uses a ratio-type helpfulness, while Yelp.com uses a count-type usefulness index. This usefulness index provides helpful reviews to future potential purchasers. This study investigated the effects of sentiment and readability on useful votes for customer reviews. Similar studies on the relationship between sentiment and readability have focused on the ratio-type usefulness index utilized by websites such as Amazon.com. In this study, Yelp.com's count-type usefulness index for restaurant reviews was used to investigate the relationship between sentiment/readability and usefulness votes. Yelp.com's online customer reviews for stores in the beverage and food categories were used for the analysis. In total, 170,294 reviews containing information on a store's reputation and popularity were used. The control variables were the review length, store reputation, and popularity; the independent variables were the sentiment and readability, while the dependent variable was the number of helpful votes. The review rating is the moderating variable for the review sentiment and readability. The length is the number of characters in a review. The popularity is the number of reviews for a store, and the reputation is the general average rating of all reviews for a store. The readability of a review was calculated with the Coleman-Liau index. The sentiment is a positivity score for the review as calculated by SentiWordNet. The review rating is a preference score selected from 1 to 5 (stars) by the review author. The dependent variable (i.e., usefulness votes) used in this study is a count variable. Therefore, the Poisson regression model, which is commonly used to account for the discrete and nonnegative nature of count data, was applied in the analyses. The increase in helpful votes was assumed to follow a Poisson distribution. Because the Poisson model assumes an equal mean and variance and the data were over-dispersed, a negative binomial distribution model that allows for over-dispersion of the count variable was used for the estimation. Zero-inflated negative binomial regression was used to model count variables with excessive zeros and over-dispersed count outcome variables. With this model, the excess zeros were assumed to be generated through a separate process from the count values and therefore should be modeled as independently as possible. The results showed that positive sentiment had a negative effect on gaining useful votes for positive reviews but no significant effect on negative reviews. Poor readability had a negative effect on gaining useful votes and was not moderated by the review star ratings. These findings yield considerable managerial implications. The results are helpful for online websites when analyzing their review guidelines and identifying useful reviews for their business. Based on this study, positive reviews are not necessarily helpful; therefore, restaurants should consider which type of positive review is helpful for their business. Second, this study is beneficial for businesses and website designers in creating review mechanisms to know which type of reviews to highlight on their websites and which type of reviews can be beneficial to the business. Moreover, this study highlights the review systems employed by websites to allow their customers to post rating reviews.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.113-116
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• 1992

소음의 발생 원인은 공기역학적 측면과 구조적 측면으로 나누어지는데, 실제 로는 유동장에서 발생되는 음원과 구조물에서 발생되는 진동과의 상호 간섭 에 의해 보다 복잡한 형태로 발생된다. 음장 문제를 두가지 범주로 구분하면 첫째는 음원과 구조물과의 상호교란에 의한 산란문제(Scattering)와 둘째로 구조물의 자체 진동에 의한 음의 전파현상과 구조물내부에 회전체와 같은 음원이 존재하는 경우에 음의 전파를 관측하는 방사문제(Radiation)가 있다. 실제로 산업용 터빈이나 비행기 엔진 흡입구에서 발생되는 소음, 또는 자동 차의 배기구를 통해 발생되는 소음 그리고 엔진의 진동에 의한 구조적 소음, 기타 가전제품의 회전체(Fan & Motor)에 의한 소음은 방사(Radiation)의 문 제로서 중요 관심 과제이다 수치적 기법으로 근래에 많이 사용하는 방법으 로 BEM(경계요소법), FEM(유한요소법), FDM(유한차분법)이 있는데 본 연 구에서는 유한요소법을 이용하기로 한다. 지금까지는 주로 BEM을 통해서 Far-Field의 음향장을 해석하였지만 복잡한 형상을 갖는 구조물내부에서의 음향장 변화나 구조물 내부에 음원이 존재하는 경우 또는 구조물 자체가 갖 는 물리적 특성치 변화 즉 물체표면에서의 부분 진동문제의 음향장 해석에 있어서 가장 잘 대체해 나갈 수 있는 방법이 유한 요소법이라고 여겨진다. 본 연구에서는 2차원 또는 기하학적으로 축대칭인 3차원 Duct내부에 음원이 존재하는 경우 음원전파에 따른 Near-field와 far-field에서 음의 방향성을 예측하기 위해 먼저 기본적인 유한요소법에 의한 Robin 경계조건을 사용하 여 계산된 결과와 Infinite Element를 도입하여 계산할 결과를 비교하여, Infinite Element가 보다 효율적이며 타당한 결과를 얻음을 확인해 보기로 한다.다 복합적인 측면에서 치료에 임하여야 할 것으로 사료된다. with such configuration.trap with 2.88[eV] deep of injected space charge from the chathode in the crystaline regions. The origin of ${\alpha}$$_2$ peak was regarded as the detrapping process of ions trapped with 0.9[eV] deep originated from impurity-ion remained in the specimen during production process of the material, in the crystalline regions. The origin of ${\beta}$ peak was concluded to be due to the depolarization process of "C=0"dipole with the activation energy of 0.75[eV] in the amorphous regions. The origin of ${\gamma}$ peak was responsible to the process combined with the depolarization of "CH$_3$", chain segment, with the activation energy of carriers from the shallow trap with 0.4[eV], in he amorphous regions.의 증발산율은 우기의 기상자료를 이용하여 구한 결과 0.05 - 0.10 mm/hr 의 범위로서 이로 인한 강우손실량은 큰 의미가 없음을 알았다.재발이 나타난 3례의 환자

• Phonetics and Speech Sciences
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• v.12 no.3
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• pp.1-14
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• 2020

Previous studies have confirmed that /o/ and /u/ in Seoul Korean are undergoing a merger in the F1/F2 space, especially for female speakers. As a substitute parameter for formants, it is reported that female speakers use phonation (H1-H2) differences to distinguish /o/ from /u/. This study aimed to explore whether H1-H2 values are being used as perceptual cues for /o/-/u/. A perception test was conducted with 35 college students using /o/ and /u/ spoken by 41 females, which overlap considerably in the vowel space. An acoustic analysis of 182 stimuli was also conducted to see if there is any correspondence between production and perception. The identification rate was 89% on average, 86% for /o/, and 91% for /u/. The results confirmed that when /o/ and /u/ cannot be distinguished in the F1/F2 space because they are too close, H1-H2 differences contribute significantly to the separation of the two vowels. However, in perception, this was not the case. H1-H2 values were not significantly involved in the identification process, and the formants (especially F2) were still dominant cues. The study also showed that even though H1-H2 differences are apparent in females' production, males do not use H1-H2 in their production, and both females and males do not use H1-H2 in their perception. It is presumed that H1-H2 has not yet been developed as a perceptual cue for /o/ and /u/.

• Journal of Labour Economics
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• v.29 no.3
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• pp.75-112
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• 2006

We found following evidences from our empirical analysis with the Workplace Panel Survey data of the Korea Labor Institute with reference to 'discord hypothesis' which insists that employee participatory high performance work practices would strengthen not only an enterprise focus in labor-management relations but also the enterprise unionism in the labor union system or collective bargaining structures, so they would probably come into conflict with the superenterprise-oriented industrial solidarity spirit in labor unionism. First, even though there are significant positive management performance effects of high performance work practices, especially in case of mining and manufacturing industries, the positive performance effects of employee participatory work practices such as job rotation ratio of workers and 6-sigma activities were much strengthened relatively in case of non-unionized establishments. Second, the superenterprise-oriented collective bargaining system is also found to give very strong and statistically significant negative performance effects to the introduction and implementation of work teams and performance-related payment systems such as profit sharing, group incentive pay system and so on. Although there are some careful reservations in interpreting the results of our analysis because of data insufficiency, they may have important implications that the industrial labor unionism or the superenterprise-oriented collective bargaining practices exercise the bargaining power to make individual firms be negative or feel it nearly impossible to introduce the employee participatory work practices which can be very favorable to improving those management performance.

• Journal of Korea Water Resources Association
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• v.42 no.7
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• pp.571-578
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• 2009

Levee-break Analysis model is developed to predict the variation of breach width according to time and to estimate inundation area and depth in protected lowland. This Model calculate flood depth using 4 point implicit finite difference method in river channel and analyze breach flow based on physical theory introducing soil transport equation and erosion process. Breach analysis model and channel flood model are combined into Levee-Break Model and this model is applied to actual levee break case. Then, this model can simulate reasonably many levee-break parameters such as river stage, breach width, breach formation and so on. If the applicability of this model is proved through applications to more various actual levee-break cases, the suggested model is expected to do more accurate flood analyses on levee break site.

• The Journal of the Acoustical Society of Korea
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• v.22 no.5
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• pp.360-366
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• 2003

Although multilayer perceptrons (MLPs) present several advantages against other pattern recognition methods, MLP-based speaker verification systems suffer from slow enrollment speed caused by many background speakers to achieve a low verification error. To solve this problem, the quantitative discriminative cohort speakers (QnDCS) method, by introducing the cohort speakers method into the systems, reduced the number of background speakers required to enroll speakers. Although the QnDCS achieved the goal to some extent, the improvement rate for the enrolling speed was still unsatisfactory. To improve the enrolling speed, this paper proposes the qualitative DCS (QlDCS) by introducing a qualitative criterion to select less background speakers. An experiment for both methods is conducted to use the speaker verification system based on MLPs and continuants, and speech database. The results of the experiment show that the proposed QlDCS method enrolls speakers in two times shorter time than the QnDCS does over the online error backpropagation(EBP) method.

• Industry Promotion Research
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• v.8 no.2
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• pp.1-9
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• 2023

To bridge the research gap in the area of the Fourth Industrial Revolution, we explore the correlation between the core technologies of the Fourth Industrial Revolution and the economic performance of companies. The results show that the technologies have a statistically significant positive (+) correlation with company sales. The size of the correlation is highest for 3D printing (139%), followed by big data (129%), cloud computing (127%), artificial intelligence (78%), and the internet of things (70%). We also found a statistically significant negative (-) interaction effect between the internet of things and 3D printing, cloud computing and big data, and cloud computing and 3D printing when examining the interaction effect of introducing core technologies of the Fourth Industrial Revolution on company sales. This paper represents an early attempt to examine the correlation between the core technologies of the Fourth Industrial Revolution and the economic performance of companies and may serve as a basis for further empirical research.