효율적인 소규모 네트워크 구축

안봉근,이병수,정현식 한국경영과학회 1995 經營 科學 Vol.12 No.3

Information sharing and automated office in the use of PC necessitate corporate network to implement business innovation. Building an efficient network requires competent knowledge on capabilities of various LAN technologies, hardwares and softwares that have rapidly improved in terms of efficiency and cost. This paper compares capabilities of network components: communication protocol, hardware, network operation system, low cost database software and mid-range priced SQL for application development. Also this study presents a new technology on virtual LAN and a selection guide among the various options of the network components which are suitable for PC-based small-sized network in balance of efficiency with economy. In the last section of this paper, a case of small-sized network is given for illustration.

측두하악 장애의 정신생리학적 측면에 대한 예비적 연구

손봉기,이정구,최인근 大韓神經精神醫學會 1991 신경정신의학 Vol.30 No.6

This study was designed to investigate the psychophysiologic aspects of temporomandibular disorder. Using various test batteries, 67subjects(33 of TMD patients and 34 of controls) were evaluated and the responses were analyzed through SPSS program. The results were as follows : 1) The score of social readjustment rating scale was significantly higher in the female patient group than in the female control group. 2) The patient group was less responsive to the pressure from financial difficulties, and the male patient group was less responsive to the changes in relationship and the pressure from financial difficulties than their respective control group. 3) Compared with the control group, the patient group was unfamiliar with the three coping strategies, namely shared concern, redefinition, and acting-out. Female patients were unfamiliar especially with the redefinition and acting-out, but very familiar with the compliance. 4) The patient group and the female patient group attained significantly higher score in Zung's self-rating depression scale than the control groups, respectively. 5) The scores of Hs. D, and Hy scales of MMPI of the patient group were significantly higher than those of the control group, and 1-3-2 type was most frequently noted in the patient group, though not significant.

피로와 의료이용, 업무상 사고 및 질병결근

장세진,고상백,강동묵,김성아,정진주,이철갑,강명근,현숙정,조정진,차봉석,박종구 大韓産業醫學會 2005 대한직업환경의학회지 Vol.17 No.4

Objectives: This study examined the relationship of fatigue to medical utilization, occupational accident and sickness absence. Subjects and Methods: Data were obtained from the National Study for Development and Standardization of Occupational Stress (NSDSOS Project, 2002~2004). A total of 30,146 employees categorized within the Korean Standard Industrial Classification and the Korean Standard Occupational Classification were recruited. A structured-questionnaire was used to assess the participants' sociodemo-graphics, job-related factors, health-related behaviors, personality trait, self=perceived fatigue (MFS) and the frequency of medical utilization, occupational accident and sickness absence. Data on medical utilization and occupational accident were confirmed from company health records. Chi-square test and logistic regression analysis were used to elucidate the relationship of self-perceived fatigue to medical utilization, occupational accident and sickness absence. Results: In logistic regression analyses, self-perceived fatigue was associated with medical utilization (outpatient), occupational accident and sickness absence although the strength of the associations was higher in the blue collar workers except for medical utilization. For medical utilization, the white collar worker's adjusted odds ratios of outpatient utilization for workers scoring in the third quartile and the highest quartile, compared to workers scoring in the lowest quartile were 1.50 (95% CI: 1.20-1.87) and 2.16 (95% CI: 1.69-2.75), respectively. The blue collar workers' adjusted odds ratios of outpatient utilization for workers scoring in the second (OR: 1.23, 95% CI: 1.06-1.43), third (OR: 1.42, 95% CI: 1.22-1.66) and highest quartile (OR:1.83, 95% CI: 1.55-2.17), respectively, compared to workers scoring in the lowest quartile were statistically significant. However, no associations were found between fatigue and inpatient utilization for either the white or blue collar workers. The blue collar workers' adjusted odds ratios of being injured for workers scoring in the second, third and highest quartile were 1.41 (95% CI: 1.00-2.00), 1.57 (95% CI: 1.10-2.22) and 2.41 (95% CI: 1.69-3.44), respectively, compared to those scoring in the lowest quartile, but, those of the white collar workers were not significant. There was more likely to an increased risk of sickness absence in workers scoring in the second, third and highest quartile compared to those scoring in the lowest quartile in both white and blue collar workers, but the magnitudes of risk were higher in the blue collar workers than the white collars workers. Conclusion: This result suggests that fatigue is a determinant predictor of medical utilization, occupational accident and sickness absence, and that the pattern of risks for the three outcomes differs according to the occupational type. Some limitations of this study and considerations for future study were also discussed.

Microfluidic fabrication of microengineered hydrogels and their application in tissue engineering.

Chung, Bong Geun,Lee, Kwang-Ho,Khademhosseini, Ali,Lee, Sang-Hoon Royal Society of Chemistry 2012 Lab on a chip Vol.12 No.1

<P>Microfluidic technologies are emerging as an enabling tool for various applications in tissue engineering and cell biology. One emerging use of microfluidic systems is the generation of shape-controlled hydrogels (i.e., microfibers, microparticles, and hydrogel building blocks) for various biological applications. Furthermore, the microfluidic fabrication of cell-laden hydrogels is of great benefit for creating artificial scaffolds. In this paper, we review the current development of microfluidic-based fabrication techniques for the creation of fibers, particles, and cell-laden hydrogels. We also highlight their emerging applications in tissue engineering and regenerative medicine.</P>

Optimal Design of Resonance Frequency for LLC Converter

Bong-Geun Chung(정봉근),Sang-Cheol Moon(문상철),Cheng-Hao Jin(김성호) 전력전자학회 2015 전력전자학술대회 논문집 Vol.2015 No.07

Micro/Nanotechnology Systems for Neural Stem Cell Differentiation

Bong Geun CHUNG 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10

Biophysical cues, such as electrical stimulus, mechanical feature, and surface topography, enable the control of neural stem cell (NSC) differentiation and neurite outgrowth. However, the effect of these biophysical cues on NSC behavior has not been fully elucidated. In the present study, we developed an innovative combinatorial biophysical cue sensor array combining a surface modified nanopillar array with conductive hydrogel micropatterns. The micro/nanopattern comprised silicon oxide-coated polyurethane nanopillar arrays on a flexible film and conductive hydrogel micropatterns including polyethylene glycol hydrogel, silver nanowires, and reduced graphene oxide. A computational fluid dynamic model was used to optimize the design parameters of the nanopillar arrays. In the study, we successfully demonstrated that the nanopillar array enhanced the differentiation of NSCs and efficiently regulated neuronal behavior, such as neurite outgrowths, by conductive hydrogel micropatterns combined with electrical stimuli. Therefore, our innovative combinatorial biophysical cue sensor array to control NSC behavior via electrical stimuli can be potentially useful to study neurodegenerative and neurological disorder therapy applications.

Microfluidic gradient platforms for controlling cellular behavior

Chung, Bong Geun,Choo, Jaebum WILEY-VCH Verlag 2010 Electrophoresis Vol.31 No.18

<P>Concentration gradients play an important role in controlling biological and pathological processes, such as metastasis, embryogenesis, axon guidance, and wound healing. Microfluidic devices fabricated by photo- and soft lithography techniques can manipulate the fluidic flow and diffusion profile to create biomolecular gradients in a temporal and spatial manner. Furthermore, microfluidic devices enable the control of cell-extracellular microenvironment interactions, including cell–cell, cell–matrix, and cell–soluble factor interaction. In this paper, we review the development of microfluidic-based gradient devices and highlight their biological applications.</P>

Functional Microfluidics and Nanoparticles for Cell Biology

Bong Geun CHUNG 한국생물공학회 2019 한국생물공학회 학술대회 Vol.2019 No.4

Micro/Nanotechnologies for Stem Cell and Cancer Biology

Bong Geun CHUNG 한국생물공학회 2017 한국생물공학회 학술대회 Vol.2017 No.10

대기전력저감을 위한 SMPS

정봉근(Bong-Geun Chung),장상호(Sang-Ho Jang),김은수(Eun-Soo Kim),최문기(Moon Gi Choi),이재삼(Jae-Sam Lee) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-

최근 대기전력저감기능을 갖는 PWM IC를 적용한 플라이백 컨버터는 대기전력 모드 시 Burst 스위칭 동작에 의해 소모 전력을 최소화 할 수 있지만 경 부하 및 대기전력모드 시 변압기를 통해 흐르는 큰 여자전류에 의해 여전히 낮은 효율특성을 가지는 문제점이 있었다. 본 논문에서는 경 부하 및 대기전력 모드 동작 시 변압기에 흐르는 여자전류를 최소화함으로 효율을 개선한 회로를 제안하였으며 50인치 PDP TV PSU (Power Supply Unit)에 있어서 대기전력 및 보조전원으로 사용된 74W 플라이백 컨버터에 적용하여 비교 검토하여 보았다.