• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.41 no.2
• /
• pp.1-8
• /
• 2018

K-means algorithm is one of the most popular and widely used clustering method because it is easy to implement and very efficient. However, this method has the limitation to be used with fixed number of clusters because of only considering the intra-cluster distance to evaluate the data clustering solutions. Silhouette is useful and stable valid index to decide the data clustering solution with number of clusters to consider the intra and inter cluster distance for unsupervised data. However, this valid index has high computational burden because of considering quality measure for each data object. The objective of this paper is to propose the fast and simple speed-up method to overcome this limitation to use silhouette for the effective large-scale data clustering. In the first step, the proposed method calculates and saves the distance for each data once. In the second step, this distance matrix is used to calculate the relative distance rate ($V_j$) of each data j and this rate is used to choose the suitable number of clusters without much computation time. In the third step, the proposed efficient heuristic algorithm (Group search optimization, GSO, in this paper) can search the global optimum with saving computational capacity with good initial solutions using $V_j$ probabilistically for the data clustering. The performance of our proposed method is validated to save significantly computation time against the original silhouette only using Ruspini, Iris, Wine and Breast cancer in UCI machine learning repository datasets by experiment and analysis. Especially, the performance of our proposed method is much better than previous method for the larger size of data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.483-485
• /
• 2010

A 200kS/s 10-bit successive approximation(SA) ADC with a rail-to-rail input range is proposed. The proposed SA ADC consists of DAC, comparator, and successive approximation register(SAR) logic. The folded-type capacitor DAC with the boosted NMOS switches is used to reduce the power consumption and chip area. Also, the time-domain comparator which uses a fully differential voltage-to-time converter improves the PSRR and CMRR. The SAR logic uses the flip-flop with a half valid window, it results in the reduction of the power consumption and chip area. The proposed SA ADC is designed by using a $0.18{\mu}m$ CMOS process with 1V supply.

• Korean Institute of Interior Design Journal
• /
• v.22 no.6
• /
• pp.68-78
• /
• 2013

The purpose of this study is to investigate Seonyudo Park and Kkummaru in terms of haptic space. This is an attempt to escape from the limits of optical space that identifies the space with abstract concepts. Haptic perception of the space refers to feeling the space with all the senses through non-hierarchical interactions. Time of the haptic space is revealed by Deleuze's crystalline description and Bergson's pure recollection that is not useful to identify objects. According to two concepts, the running present forks into the past and the future, and the nature of time appears at the point of indiscernibility in which the past, present, and future coexist. Thought on time about the architecture provides a valid point of view to understand the relationship of visitor's sensory experience of space, recollection, and emotion. In this respect, it can be said that Joh sung-yong's two works explored for new areas of architectural experience by building up the potential image of the subject which is placed in the human memory. And then this study shows that two works recover the relationship between the past and the present so that they give an opportunity to consider the meaning of time in the architecture.

• International conference on construction engineering and project management
• /
• 2015.10a
• /
• pp.336-338
• /
• 2015

This research is to propose an applicable framework for real-time health surveillance and safety monitoring at construction sites. First this study aims at finding (1) a framework for health surveillance that is likely to benefit employers and employees in the industry, (2) a valid way to identify factors or conditions with potential health concerns that can occur under particular work conditions, (3) An effective way to apply wireless/mobile sensors to construction workers using real-time/live data transmission methods, and (4) A relationship between a worker's vital signs and job site environment. Biosensors for physiological response and devices for weather/work related data are to collect real-time data. Relationships between jobs and physiological responses are analyzed and factors that touched particularly contributing to certain responses are identified. When data are incorporated with tasks, factors affecting tasks can be identified to estimate the magnitude of the factors. By comparing work and normal responses possible precautionary actions can be considered. In addition, the study would be lead to improving (1) trade-specific dynamic work schedules for workers which would be based on various factors affecting worker health level and (2) reevaluating worker productivity with health status and work schedule, thereby seeking ways to maximize worker productivity. Through a study, the paper presents expected benefits of implementing health monitoring.

• International Journal of Internet, Broadcasting and Communication
• /
• v.15 no.4
• /
• pp.342-350
• /
• 2023

The purpose of this study is to find out how the perceived waiting time of viewers of e-sports games affects negative emotions and how these negative emotions affect viewing satisfaction, viewing attitude, and continuous viewing intention. To achieve the purpose of this study, 200 viewers who watched e-sports games more than two to three times were targeted. 197 copies were selected as the final valid sample after excluding three of the collected questionnaires that showed unfaithful answers. For data processing methods, confirmatory factor analysis, reliability analysis, and structural equation model analysis were conducted using SPSS 27 and AMOS 25. Through this, the following results were obtained. First, it was found that the perceived waiting time of the viewer had a significant effect on the viewers' negative emotions in the event of a game pause. Second, viewers' negative emotions were found to have a significant effect on viewing attitudes, but not on viewing satisfaction. Third, it was found that viewing attitude had a significant effect on viewing satisfaction and continuous viewing intention. Fourth, it was found that viewing satisfaction had a significant effect on continuous viewing intention. In other words, the more acceptable and shorter the perceived waiting time due to the suspension of the game pause, the lower the negative emotions of the viewers, and the negative emotions of the viewers ultimately affect the intention to continue watching through viewing attitude and viewing satisfaction.

• Structural Engineering and Mechanics
• /
• v.32 no.3
• /
• pp.407-427
• /
• 2009

A fundamental solution for the transient, quasi-static, plane problems of linear viscoelasticity is introduced for a specific material. An integral equation has been found for any problem as a result of dynamic reciprocal identity which is written between this fundamental solution and the problem to be solved. The formulation is valid for the first, second and mixed boundary-value problems. This integral equation has been solved by BEM and algorithm of the BEM solution is explained on a sample, mixed boundary-value problem. The forms of time-displacement curves coincide with literature while time-surface traction curves being quite different in the results. The formulation does not have any singularity. Generalized functions and the integrals of them are used in a different form.

• Journal of Institute of Control, Robotics and Systems
• /
• v.10 no.3
• /
• pp.232-238
• /
• 2004

The brake system of a high-speed train has a crucial role for the safety of human mass transportation. However, it is hard to acquire design parameters of the brake system in the design step of the new high-speed train. In this paper, we build a HILS (Hardware In-the- Loop Simulation) system for the brake system of the Korea High-Speed Train (KHST) that is supposed to run up to 350 km/h, and analyze the characteristics of the brake system of the KHST (composed of 7 cars) via real-time simulations. In the HILS system that is built using a DSP board of dSPACE, the dynamics of the 7 car bodies and several bogies and characteristics of springs and dampers of connection devices between cars are considered separately. Simulation results show that the designed brake system of the KHST is valid and satisfies design specifications.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.9
• /
• pp.3680-3692
• /
• 2020

The purpose of this study is to orient users' touchpoints in co-design experience, to identify their need via visualized experience map, to recommend valid design information in online e-customization services. A user-centered co-design experience map (UCEM) is adopted to analyze the relation between users' desire and time spent, so as to evaluate the online co-design experiences. Based on evolutionary algorithm and fuzzy theory, data of this study is collected from 30 participants. The data was analyzed by descriptive analysis in SPSS, and frequency query and word cloud in NVivo. Employing design category and evaluating users' time spent, the findings are that (a) vamp color matching is consistent with interview data; (b) supported by qualitative feedback, the virtual experience map played an important role in the co-design process and the visualized interaction process; and (c) participants prefer to get more information and professional help on color matching and exterior design. Based on the findings in design category, future work should be focused on developing a better understanding of design resource recommendations and multi-stakeholder communication.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.1
• /
• pp.1-11
• /
• 1998

For the analysis of phonon heat transfer within short time and spatial scales, conventional macroscopic heat conduction equations with jump boundary conditions are tried and the results are compared to those of equation of phonon radiative transport(EPRT), which is one of microscopic transport equation. In transient state the macroscopic temperatures show far different behavior from EPRT. In steady state the hyperbolic temperatures with temperature jump at the wall from time relaxation model agrees well with EPRT temperatures. Since EPRT is also an approximate form of microscopic transport equation and there are no experimental results to verify the proposed model in this study, we can not conclude whether the approaching method from this study is valid or not. To the authors' knowledge, there are no experimental results available which can be used to test the validity of these models. Such an experiment, while difficult to conduct, would be invaluable.

• Management Science and Financial Engineering
• /
• v.10 no.2
• /
• pp.53-71
• /
• 2004

In this study, a mathematical model that shows the optimal payout policy is developed. The model is new and unique in the sense that not only continuous-time framework is used, but also both partial differential equation (PDE) and real-option approach are utilized in the derivation of optimal payouts for the first time. In the model building, non-linear demand curve for dividend payouts in the competitive capital markets is assumed. From the sensitivity analysis using traditional comparative static analysis, some useful managerial implications which are consistent with famous previous studies are derived under realistic conditions. All results in this study, however, are valid under the assumption that the opportunity costs follow geometric Brownian motion, which is widely used in economic science and finance literature.