Pohang, South Korea
Pohang, South Korea

Time filter

Source Type

Jang H.M.,Gwangju Institute of Science and Technology | Choi S.S.,Semyung University | Ha J.H.,Pyeongtaek University
Applied Chemistry for Engineering | Year: 2016

In this study, single-stage continuous anaerobic reactors to treat sewage sludge were operated under different temperature (55 and 35 °C RTAD and RMAD) to evaluate the reactor stability and performance of the thermophilic and mesophilic anaerobic digestion. During the overall digestion, both anaerobic reactors maintained quite stable and constant pH and total alkalinity (TA) values in the range of 6.5-8.0 and 3-4 g CaCO3/L, respectively. After the start-up period, RTAD showed 10% higher VS removal efficiency than that of RMAD (RTAD; 43.3%; RMAD: 33.6%). Although organic acids such as acetic and propionic acid were detected in both anaerobic reactors at the start-up period, all organic acids in RTAD and RMAD were consumed at the steady state condition. Also RTAD showed 31.4 % higher methane production rate (MPR) than that of RMAD at the steady state condition (RTAD; 243 mL CH4/L/d; RMAD: 185 mL CH4/L/d). Meanwhile, the experimental results indicated similar methane yield between RTAD and RMAD. © 2016, Korean Society of Industrial Engineering Chemistry. All rights reserved.

Yoon Y.H.,Pyeongtaek University | Bong C.,GreenSolus Co. | Kim D.S.,Seoul National University
Particuology | Year: 2015

The use of soft X-rays in a neutralizer represents an alternative technique that could replace conventional radioactive sources. In this study, we evaluated the charging characteristics of a soft X-ray aerosol neutralizer. In addition, the results from the evaluation of the soft X-ray charger were compared with results obtained using a neutralizer incorporating an 241Am radioactive source. The tandem differential mobility analyzer technique was used previously to determine the size-dependent positive, negative, and neutral charge fractions of a soft X-ray neutralizer. This technique was used to show that the neutral fractions obtained using the soft X-ray charger agreed well with the predictions of bipolar diffusion charging theory, and that the soft X-ray charger could be used as a neutralizer for a scanning mobility particle sizer system. © 2014 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

PubMed | Korea University, University of Ulsan, Pyeongtaek University, Kyung Hee University and 2 more.
Type: | Journal: Journal of Korean medical science | Year: 2016

This study is part of a 5-year research project on the national burden of diseases, injuries, and risk factors in Korea. Using disability-adjusted life years (DALYs), a metric introduced by the 1990 Global Burden of Disease (GBD) project, we performed a comprehensive and detailed assessment of the magnitude and distribution of both fatal and non-fatal health problems in the Korean population. The concept and general approach were consistent with the original GBD study, with some methodological modifications to make the study more suitable for Korea. We computed DALYs for 313 causes in both sexes and nine age groups using the entire populations medical records and newly generated Korean disability weights. In 2012, the dominant disease burden was non-communicable diseases, which accounted for 85.21% of total DALYs, while injuries accounted for 7.77% and communicable, maternal, neonatal, and nutritional disorders for 7.02%. Of the total DALYs, 88.67% were from years lived with disability and 11.32% were from years of life lost due to premature mortality. Diabetes mellitus was the leading cause of DALYs, followed by low back pain, chronic obstructive pulmonary disease, ischemic heart disease, ischemic stroke, cirrhosis of the liver, falls, osteoarthritis, motorized vehicle with three or more wheels, and self-harm. The results reported here identify key health challenges and opportunities for future health interventions and policy changes, and provide information that will help assess the major public health issues in Korea, a nation faced with one of the worlds most rapidly ageing populations.

Byun J.W.,Pyeongtaek University | Lee D.H.,Korea University
Journal of Systems and Software | Year: 2011

Abstract: We study a security model for searching documents containing each of several keywords (conjunctive keyword search) over encrypted documents. A conjunctive keyword search protocol consists of three entities: a data supplier, a storage system such as database, and a user of storage system. A data supplier uploads encrypted documents on a storage system, and then a user of the storage system searches documents containing each of several keywords with a private trapdoor. That is, a valid user is able to use boolean combinations of queries. Up to now only few conjunctive keyword search schemes have been proposed in the literature. However, the relying security model has not been based on relational databases such as Oracle and MS-Access, hence it is not easy to apply them in practice. Moreover, they have not considered an important security notion for user's trapdoor queries. In this paper, we first formally define a security model for conjunctive keyword search schemes including trapdoor security based on a practical relational database. We apply our security model to the existing conjunctive keyword scheme and discuss its vulnerability and countermeasure. © 2011 Elsevier Inc.

Jeung E.T.,Changwon National University | Lee K.R.,Pyeongtaek University
International Journal of Control, Automation and Systems | Year: 2014

This paper presents a design method of static output feedback control for continuous-time T-S fuzzy systems. Based on parallel distributed compensation (PDC), a static output feedback control is utilized. A new sufficient condition for the existence of static output feedback gains is represented in terms of linear matrix inequalities (LMIs). The sufficient condition does not need any transformation matrices, equality constraints, and block diagonal assumption of positive definite matrices in order to convert a bilinear matrix inequality (BMI) problem to an LMI one. © 2014 Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg.

Park N.,University of Oklahoma | Oh H.S.,Pyeongtaek University | Kang N.,Dankook University
Computers in Human Behavior | Year: 2012

This study examined the roles of social norms and individual differences in influencing Internet users' intention to upload content on Wikipedia in South Korea. It also compared the impacts of these variables on the uploading intention between users and non-users of Wikipedia. Using data from a survey of college students (185 Wikipedia users and 158 non-users), the study found that the effect of social norms including descriptive norm and injunctive norm was smaller than expected, while that of individual differences - self-efficacy, issue involvement, and ego involvement - was more important in accounting for the intention to upload. Theoretical implications and limitations were discussed. © 2012 Elsevier Ltd. All rights reserved.

Jeong H.-J.,Pyeongtaek University | Hong S.-J.,Kyung Hee University
Lecture Notes in Electrical Engineering | Year: 2012

Recently, software quality model is very important factor in software environment and society. Therefore we would like to discuss what the quality model for software is and what quality model's factor is important. This paper mainly refer from ISO 9126 model. © 2012 Springer Science+Business Media B.V.

Jung H.-J.,Pyeongtaek University | Hong S.-J.,Pyeongtaek University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Software quality control is very important. We have concern about software reliability deeply. Many research workers study about software reliability. We want to evaluate software quality as quantity. Especially, we worry about software failure data. We have to find the method software reliability by using software failure data. We propose that software test cases for evaluating of software functionality and usability. We propose that the evaluating of software reliability. We introduce the international standards of software quality control. Also, in this paper, we propose the quality testing metric for those criteria. Our evaluation method of software quality is based on the international standards ISO/IEC 9126-2 and ISO/IEC 25000 series. © 2012 Springer-Verlag.

Byun J.W.,Pyeongtaek University
Security and Communication Networks | Year: 2015

In this paper, we suggest a new privacy preserving smartcard-based password authenticated key exchange (SC-PAKE) with provable security. Only the user who has two secrets (smartcard and password) can go through authentication with key exchange while concealing its identifier from outsider adversaries. For guaranteeing both authentication and identity (ID) protection, we define a security of session key and an anonymity of identifier. We also show that the proposed protocol satisfies two definitions under computational Diffie-Hellman assumption and chosen ciphertext attack (CCA) secure symmetric encryption. One problem is how a common secure key (an encryption/decryption key) can be shared between a server and a user without letting the corresponding server know a certain ID of user. For this issue, we set two kinds of long-term secrets; one is used to make a symmetric key for ID protection with user's ephemeral value, and the other is issued for helping agreement of a final session key for mutual authentication. Performance analysis shows that the proposed SC-PAKE has better efficiency in computation and communication costs than recent SC-PAKE schemes. To the best of our knowledge, it is the first scheme to guarantee both the session key security with authentication and privacy-enjoying provable security. © 2015 John Wiley & Sons, Ltd.

Lee K.R.,Pyeongtaek University
Journal of Institute of Control, Robotics and Systems | Year: 2012

This paper presents a developing method of smart fingerprint recognition system. First, we design a hardware configuration circuit using a 32bit Risc CPU, a fingerprint sensor, a LCD, and a WiFi communication chip to realize the smart fingerprint recognition systems. It is necessary to develop a JNI (Java Native Interface) library and a device drive program of fingerprint sense to develop application program of fingerprint recognition system with Android platform. Thus second, we develop a device drive and a JNI program. And we also develop an application program of fingerprint recognition systems using developed JNI library. Finally test results are presented to illustrate the performance of the developed smart fingerprint recognition system. © ICROS 2012.

Loading Pyeongtaek University collaborators
Loading Pyeongtaek University collaborators