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Search Results: 1 - 10 of 58197 matches for " Jun Sung Kim "
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Authenticated Privacy Preserving Pairing-Based Scheme for Remote Health Monitoring Systems  [PDF]
Kambombo Mtonga, Eun Jun Yoon, Hyun Sung Kim
Journal of Information Security (JIS) , 2017, DOI: 10.4236/jis.2017.81006
Abstract: The digitization of patient health information has brought many benefits and challenges for both the patients and physicians. However, security and privacy preservation have remained important challenges for remote health monitoring systems. Since a patient’s health information is sensitive and the communication channel (i.e. the Internet) is insecure, it is important to protect them against unauthorized entities. Otherwise, failure to do so will not only lead to compromise of a patient’s privacy, but will also put his/her life at risk. How to provide for confidentiality, patient anonymity and un-traceability, access control to a patient’s health information and even key exchange between a patient and her physician are critical issues that need to be addressed if a wider adoption of remote health monitoring systems is to be realized. This paper proposes an authenticated privacy preserving pairing-based scheme for remote health monitoring systems. The scheme is based on the concepts of bilinear paring, identity-based cryptography and non-interactive identity-based key agreement protocol. The scheme also incorporates an efficient batch signature verification scheme to reduce computation cost during multiple simultaneous signature verifications.
Quantitative Analysis of Matrine and Oxymatrine in Sophora flavescens Extract and Its Biopesticides by UPLC  [PDF]
Sung Jin Lim, Du Yun Jeong, Geun Hyoung Choi, Byung Jun Park, Jin Hyo Kim
Journal of Agricultural Chemistry and Environment (JACEN) , 2014, DOI: 10.4236/jacen.2014.32008

Successive cartridge clean-up method for the simultaneous determination of matrine and oxyma- trine in biopesticides containing Sophora flavescens extract was developed and validated by UPLC. The clean-up method was established with ENVI-Carb (0.5 g) and C18 SPE (0.5 g) cartridges for the bioactive alkaloid in biopesticides from S. flavescens, and the eluate was analyzed to quantify the matrine and oxymatrine by UPLC. The developed method was validated, and the recovery and LOQ of both materials were 105.0% and 103.6%, and 0.050 and 0.684 mg·kg-1, respectively. Of the twenty one samples, the total content of matrines were analyzed by using the developed method and the result showed the developed successive clean-up method could contribute to the manufacture

Time Reversibility of Quantum Diffusion in Small-world Networks
Sung-Guk Han,Beom Jun Kim
Physics , 2012, DOI: 10.3938/jkps.60.665
Abstract: We study the time-reversal dynamics of a tight-binding electron in the Watts-Strogatz (WS) small-world networks. The localized initial wave packet at time $t=0$ diffuses as time proceeds until the time-reversal operation, together with the momentum perturbation of the strength $\eta$, is made at the reversal time $T$. The time irreversibility is measured by $I \equiv |\Pi(t = 2T) - \Pi(t = 0)|$, where $\Pi$ is the participation ratio gauging the extendedness of the wavefunction and for convenience, $t$ is measured forward even after the time reversal . When $\eta = 0$, the time evolution after $T$ makes the wavefunction at $t=2T$ identical to the one at $t=0$, and we find I=0, implying a null irreversibility or a complete reversibility. On the other hand, as $\eta$ is increased from zero, the reversibility becomes weaker, and we observe enhancement of the irreversibility. We find that $I$ linearly increases with increasing $\eta$ in the weakly-perturbed region, and that the irreversibility is much stronger in the WS network than in the local regular network.
Dynamic behaviors in directed networks
Sung Min Park,Beom Jun Kim
Quantitative Biology , 2006, DOI: 10.1103/PhysRevE.74.026114
Abstract: Motivated by the abundance of directed synaptic couplings in a real biological neuronal network, we investigate the synchronization behavior of the Hodgkin-Huxley model in a directed network. We start from the standard model of the Watts-Strogatz undirected network and then change undirected edges to directed arcs with a given probability, still preserving the connectivity of the network. A generalized clustering coefficient for directed networks is defined and used to investigate the interplay between the synchronization behavior and underlying structural properties of directed networks. We observe that the directedness of complex networks plays an important role in emerging dynamical behaviors, which is also confirmed by a numerical study of the sociological game theoretic voter model on directed networks.
A Hybrid Structure of Dual Stators and a Pneumatic Spring for Resonance Control in an Air Mount  [PDF]
Hyung-Tae Kim, Cheol-Ho Kim, Sung-Bok Kang, Seok-Jun Moon, Gyu-Seop Lee
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.53019

An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to 10 dB.

Distribution of Eye Diseases in Kasungu District, Malawi, Central Africa—A Retrospective Cross-Sectional Study  [PDF]
Richard Kang, Jae Jun Kim, Paul Chung, Gyuri Hwang, Jung Sung Kim, Seunghan Baek, Eun Jung Im, George Talama
Advances in Infectious Diseases (AID) , 2018, DOI: 10.4236/aid.2018.82008
Abstract: Analysis of eye diseases of patients at Kasungu District Hospital in Malawi was made. Malawi is one of the poorest countries in the world and the health system faces a lot challenges in terms of resources. The study was, therefore, done to understand the burden and distribution of eye diseases in this resource-limited setting. A retrospective study was conducted by extracting data from data registers in the outpatient eye department for the period of May 2015 to June 2016. The data of the reported eye diseases analyzed with variables such as patient gender, eye disease type, patient age and times of the year. There was no association between eye diseases and gender nor with times of the year. However, it was noted that the commonest type of eye disease was conjunctivitis. And, there was strong association of some disease type with age, for example, conjunctivitis was common in young age group while cataract was common in the elderly. It was shown in this study that many of the eye diseases endemic in Africa do generally occur in this selected district as well. However, the analysis presents the possibility of reducing the incidences of many diseases by preventive measures and access to health facilities on time.
Hip External Rotator Strength and Compensatory Movement in Three Different Positions  [PDF]
Sun-Hee Ahn, Ui-Jae Hwang, Sung-Hoon Jung, Hyun-A Kim, Jun-Hee Kim, Oh-Yun Kwon
Health (Health) , 2018, DOI: 10.4236/health.2018.101011
Abstract: Measuring intrinsic hip external rotator strength (ER) without compensatory pelvic motion and activation of the sartorius is important for preventing or rehabilitating lower extremity injuries. However, the optimal method for measuring intrinsic hip ER muscle strength while minimizing compensatory pelvic motions and activation of the sartorius is unclear. The purpose of this study is to compare measurements of hip ER strength, compensatory pelvic motion, and sartorius activation in the sitting, prone, and sidelying positions. Thirty-one healthy subjects (16 males and 15 females) were recruited for this study. Hip ER strength, pelvic kinematics, and sartorius muscle activation were measured during maximal isometric contraction of the hip ER in the sitting, prone, and sidelying positions. Hip ER strength was measured using a load-cell-type strength-measurement sensor. Pelvic kinematics was measured using an electromagnetic motion-tracking sensor. Electromyography was used to measure sartorius muscle activity. Data were analyzed using one-way repeated-measures analysis of variance. The result showed that hip ER strength and sartorius muscle activation were significantly lower in the sidelying compared with the sitting and prone positions (p < 0.01). Pelvic anteroposterior tilting was significantly greater in the sitting compared with the prone and sidelying positions (p < 0.01). Pelvic rotation differed significantly among positions (p < 0.01). Pelvic lateral tilting was significantly greater in the prone compared with the sitting position (p < 0.017). Compensatory pelvic motion and sartorius muscle activation were lower when hip ER strength measurements were made in the sidelying position. Therefore, the sidelying position is effective for measuring selective intrinsic hip ER strength.
Maximizing Memory Data Reuse for Lower Power Motion Estimation
Bo-Sung Kim,Jun-Dong Cho
VLSI Design , 2002, DOI: 10.1080/10655140290011096
Abstract: This paper presents a new VLSI architecture of the Motion Estimation in MPEG-2. Previously, a number of full search block matching algorithms (BMA) and architectures using systolic array have been proposed for motion estimation. However, the architectures have an inefficiently large number of external memory accesses. Recently, to reduce the number of accesses in one search block, a block matching method within a search area to reuse the search data is provided using systolic process arrays. To further reduce the data access and computation time during the block matching, we propose a new approach through the reuse of the previously-search data in two dimensions. Our new architecture in this paper is an extension from our previous work such that we reuse the previously-searches area not only between two consecutive columns but also between two consecutive rows, so as to entirely remove redundant memory accesses. Experimental results show that our architecture of increased area by 81% can reduce 98% of memory accesses. Total power reduction is 86% in power estimation by SPICE model.
Fast and low-temperature reduction of graphene oxide films using ammonia plasma
Maeng Jun Kim,Yonkil Jeong,SangHo Sohn,Sung Yeup Lee
AIP Advances , 2013, DOI: 10.1063/1.4789545
Abstract: Reduced graphene oxide (rGO) has been produced using an ammonia (NH3) plasma reduction method. Simultaneous nitrogen doping during the reduction process enabled a rapid and low-temperature restoration of the electrical properties of the rGO. The chemical, structural, and electrical properties of the rGO films were analyzed using x-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, and conductivity measurements. The oxygen functional groups were efficiently removed, and simultaneous nitrogen doping (6%) was carried out. In addition, the surface of the rGO film was flattened. Consequently, the rGO films exhibited electrical properties comparable to those prepared via other reduction methods.
Numerical and Experimental Study on the Combustion and Emission Characteristics of a Dimethyl Ether (DME) Fueled Compression Ignition Engine études numériques et expérimentales sur les caractéristiques de combustion et d’émissions d’un éther diméthylique (EDM)- moteur à auto-allumage rempli de combustible
Kim Hyung Jun,Park Sung Wook,Lee Chang Sik
Oil & Gas Science and Technology , 2012, DOI: 10.2516/ogst/2011130
Abstract: A numerical investigation was carried out to study on the combustion and emission characteristics of dimethyl ether (DME) with wide ranges of injection timings in compression ignition engines. In order to simulate DME combustion processes, a KIVA-3V code coupled with a chemistry solver was used to solve the detailed chemical kinetics model of DME oxidation. In addition, the Kelvin-Helmholtz-Rayleigh-Taylor (KH-RT) hybrid breakup model and Renormalization Group (RNG) k-ε models were applied to analyze the spray characteristics and turbulent flow, respectively. To predict the NOx formation during DME combustion, a reduced Gas Research Institute (GRI) NO mechanism was used. From these results on the combustion and emission, the calculated results were compared with experimental ones for the same operating conditions. In the combustion characteristics, the calculated combustion pressure and heat release rates agreed well with experimental results. The levels of experimental NOx emissions was reduced as the start of the injection timing retarded, and also these trends appeared in calculated emission characteristics. Additionally, the calculated CO and HC emissions show an increasing trend as the start of the injection is retarded. Dans cette étude, nous considérons la simulation de la combustion du dimethyl ether (DME) dans un moteur à allumage par compression. Les caractéristiques de la combustion ainsi que les émissions polluantes sont analysées sur une large gamme d’avance à l’injection. Afin de simuler le processus de combustion du EDM, le code KIVA-3V couplé à un solveur chimique a été utilisé pour résoudre la cinétique détaillée de l’oxydation du EDM. Le modèle de rupture de Kelvin-Helmholtz-Rayleigh- Taylor (KH-RT) ainsi que le modèle de turbulence k-ε RNG ont été appliqués pour analyser respectivement les caractéristiques du jet et l’écoulement turbulent. Pour prévoir la formation de NOx pendant la combustion du EDM, le mécanisme réduit du GRI a été employé. Les résultats de simulation pour la combustion et les émissions polluantes ont été comparés aux résultats expérimentaux dans les mêmes conditions de fonctionnement. Concernant les calages de combustion, la pression moyenne simulée et les taux de chaleur dégagée sont en bon accord avec les résultats expérimentaux. Les niveaux d’émissions de NOx expérimentaux ont été réduits à mesure que l’injection est retardée; cette tendance est correctement reproduite par la simulation. Enfin, les prédictions sur les émissions en monoxyde de carbone et en hydrocarbure montrent une tendance croissante à mesure
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