• Safety and Health at Work
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• v.7 no.1
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• pp.49-54
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• 2016

Background: Prolonged sitting leads to low back discomfort and lumbopelvic muscle fatigue. This study examined the characteristics of body perceived discomfort and trunk muscle fatigue during 1 hour of sitting in three postures in office workers. Methods: Thirty workers sat for 1 hour in one of three sitting postures (i.e., upright, slumped, and forward leaning postures). Body discomfort was assessed using the Body Perceived Discomfort scale at the beginning and after 1 hour of sitting. Electromyographic (EMG) signals were recorded from superficial lumbar multifidus, iliocostalis lumborum pars thoracis, internal oblique (IO)/transversus abdominis (TrA), and rectus abdominis muscles during 1 hour of sitting. The median frequency (MDF) of the EMG power spectrum was calculated. Results: Regardless of the sitting posture, the Body Perceived Discomfort scores in the neck, shoulder, upper back, low back, and buttock significantly increased after 1 hour of sitting compared with baseline values ($t_{(9)}=-11.97$ to -2.69, p < 0.05). The MDF value of the EMG signal of rectus abdominis, iliocostalis lumborum pars thoracis, and multifidus muscles was unchanged over time in all three sitting postures. Only the right and left IO/TrA in the slumped sitting posture was significantly associated with decreased MDF over time (p = 0.019 to 0.041). Conclusion: Prolonged sitting led to increased body discomfort in the neck, shoulder, upper back, low back, and buttock. No sign of trunk muscle fatigue was detected over 1 hour of sitting in the upright and forward leaning postures. Prolonged slumped sitting may relate to IO/TrA muscle fatigue, which may compromise the stability of the spine, making it susceptible to injury.

• Korean Journal of Exercise Nutrition
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• v.16 no.1
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• pp.43-50
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• 2012

This study was designed to investigate the effect of vibratory stimulation on recovery of muscle function from delayed onset muscle soreness (DOMS). Volunteers performed 3 set of 70 % maximal voluntary eccentric muscle contraction and induced DOMS. volunteers were allocated to one of three treatment group after DOMS : group I (control), group II (ultrasound), group III (vibration). Maximal Voluntary Isometric Contraction (MVIC), Visual Analog Scale (VAS), Range Of Motion (ROM), Root Mean Square (RMS), Median frequency (MDF), Blood Serum Creatine Kinase (CK), Lactic dehydrogenase (LDH) were recorded at baseline, and 24, 48, 72 hours post-exercise. In MVIC measurement, there was a statistically significant difference in group III compared to group I (p < .05). In VAS measurements, there were a statistically significant difference in group II and III compared to group I (p < .05). In ROM measurement, there was a statistically difference in group II and III compared to group I (p < .05). In Muscle Volume with Ultrasonography measurement, there was no statistically significant difference in any groups (p > .05). In RMS and MDF measurement, there were a statistically significant difference in group II and III compared to group I (p < .05). In Blood samples of CK and LDH measurements, There were no statistically significant difference in any groups (p > .05). From the above result, Vibratory stimulation had a positive effect on recovery of muscle function from delayed onset muscle soreness. Further studies should be undertaken to ascertain the more effectiveness of vibratory stimulation and may be a promising treatment modality.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.112-117
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• 2017

This study demonstrated the emission of combustion gases of medium density fibreboard (MDF)s coated with piperazinomethyl-bis-phosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (MDEDAP), or bis-(dimethylaminomethyl) phosphinic acid (DMDAP). Each MDFs were coated in three times with a brush with 15 wt% aqueous solution of the phosphorus-nitrogen acid additives. After the specimens were dried at room temperature, the emission of combustion gases was tested using a cone calorimeter (ISO 5660-1, 2). The peak smoke production rate ($SPR_{peak}$) of the specimens coated with phosphorus-nitrogen acids was 18.5 to 41.5%, which is lower than that of using the virgin plate. However, the production of peak carbon monoxide ($CO_{peak}$) was 6.7 to 24.2% higher than that of using the virgin plate. Also, the peak carbon dioxide ($CO_{2peak}$) was 4.2 to 24.4% lower than that of using virgin plate. While the peak oxygen depletion rate was much higher than the level of 15%, which can be fatal to humans and the resulting risk could thus be eliminated. Overall, the combustibility of coated specimens was partially suppressed, but showed a negative effect on the reduction of carbon monoxide.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.546-555
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• 2009

To study an effective use of woods, three-ply hybrid laminated woods instead of crosslaminated woods which are composed of spruce in the face and three kinds of wood-based boards (MDF, PB, OSB) in the core were manufactured, and the effect of constitution elements for the core laminae on bending strength performances was investigated. Bending modulus of elasticity (MOE) of hybrid laminated woods had the highest values for the hybrid laminated wood types arranging OSB laminae in the core, and had the lowest values for those arranging MDF laminae in the core. These values were higher than those of various cross-laminated woods. The estimated bending MOEs of the hybrid laminated woods which were composed of perpendicular-direction lamina of spruce in the faces were similar to their measured values, regardless of wood-based boards in the core. However, those of the hybrid laminated woods which were composed of parallel-direction lamina of spruce in the faces had much higher values than those of their measured values, and it was necessary to revise the measured values. Bending modulus of rupture (MOR) of the hybird laminated woods had the highest value for those arranging OSB laminae in the core, and had the lowest values for those arranging PB laminae in the core unlike the bending MOE. By hybrid laminating, the anisotropy of bending strength performances was markedly decreased, and the differences of strength performances among wood-based boards were also considerably decreased.

• The Journal of Korea Robotics Society
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• v.4 no.2
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• pp.155-162
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• 2009

A main distributing frame(MDF) is an interface unit that is used to connect office equipment cables in a telephone company to subscriber cables. Until now, there is no automated switching system for MDFs in Korea. Manual handling of an MDF has some drawbacks; It is time-consuming, very cumbersome, and expensive. It also makes maintenance hard. An automated main distributing frame system is proposed and commercialized in Japan. In that system, a robot gripper inserts connecting pins into the cross point holes of a matrix board, which reveals several disadvantages in the aspects of space, maintenance, fault tolerance, and economical efficiency. This paper describes a newly developed robotic switch board system for MDFs. In the developed system, switches are placed at the cross point of a matrix board. There is one robot in between two switch units, so one robot deals with two switch units. In the system, positioning the robot, opening and closing switches can be done by using only a pair of motors and a pair of solenoids. The newly developed system is compact in size, reduces cost, and shows high reliability.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.6 no.1
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• pp.31-42
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• 2008

This study performed in order to investigate the effect of isometric resistance exercise for vastus medialis oblique muscle with EMG(electromyography) biofeedback training which are applied to the patello-femoral joint of patients with osteoarthritis on the improve of function. The subjects had no neuromuscular disorders, and they were elder patients with osteoarthritis, 20 women. And the experiment was performed in control group, taping with EMG biofeedback training group respectively, and the measurement was carried out before and after the treatment and 4 weeks after the treatment. Motor unit action potential analysis with surface electromyography showed a significant change in RMS(root mean square) amplitude and MDF(median frequency) in vastus medialis oblique muscle(p<0.05). VMO/VL(vastus medialis oblique/vastus lateralis oblique) MDF ratio showed a significant change between groups(p<0.05). Taping with EMG biofeedback training applied to patello-femoral joint of osteoarthritis patients appeared to be effective for muscle function improvement. However, increase of muscular force in vastus medialis oblique muscle appears to have a positive effect on improve of function along with correction effect on patella malalignment. In conclusion, in case of osteoarthritis patients with loss of patello-femoral joint function, it appears to be effective to practice isometric resistance exercise of vastus medialis oblique muscle selective with taping.

• Journal of the Korea Furniture Society
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• v.20 no.1
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• pp.42-51
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• 2009

As wine culture becomes popular among the people in modem society, the consumption of wine has increased due to the need to enjoy wine at home. Nonetheless, the development of wine cabinet has not made much progress. In order to compensate such matter, a wine cabinet that satisfies the taste of new generation as well as the need demanded in the modem living space is transcended its simple and solemn image embedded in wooden colored form, which is often found in existing products. First of all, the definition, kind, bottles, and glasses of wine are examined and then a cabinet is developed depending on the design process. The body of the wine cabinet is finished with black lacquer after attaching ash-patterned veneer on MDF and the front plate of the drawer is finished with the colors displayed in Mondrian's painting on MDF. The upper part is designed to store wine glasses and below the wine rack is the space for wine storage considering the overall shape. The storage at the lower part is equipped with drawers of different sizes to emphasize practicability. In conclusion, such a unique design is believed to introduce the importance of design to the domestic furniture market being a foundation for the furniture industry.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.4
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• pp.86-91
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• 2009

Indirect Touch switch which detects the change of capacitance around the electrode of QT113H chip from QPROX is designed and assembled. Sensitivity analysis of dielectric materials which prevents electrodes from direct touch is performed and the results are displayed in tables and graphs. Glass, acryl, and MDF is used to insulate the electrode and to measure the operating sensitivity of indirect touch switch. While the difference of permittivity of the dielectric materials are large, it is confirmed that the operating sensitivity of each dielectric materials are not so large as the differences of those of dielectric materials.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.85-104
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• 2002

최근 정부(정보통신부)는 사이버 아파트를 포함하여 초고속 정보통신망을 2005년까지 구축하여 각 가정당 10Mbps의 고속 정보통신서비스를 실현한다는 계획을 발표하고, 초고속 정보통신을 활성화하므로 정보통신 선진국 진입을 위하여 "초고속 정보통신 건물 인증제도"를 발표, 현재 시행하고 있다. (1999.7 제정발표) 그러나 시행 과정에서 아파트 중앙 관리실에 있는 MDF 이후의 광케이블과 기타 공사는 건설회사에서 시공하고 중앙 관리실 MDF 이전의 광케이블 공사와 중앙관리실 LAN시설 등의 공사는 통신 전문업체로 하여금, 입주자 별도 부담금으로 시공하고 있다. (컨소시엄구성) 최근 아파트 분양열기 고조로 건설회사 마다 "초고속 정보통신아파트"인증 1등급이라고 선전 및 분양광고 중인데 실제는 "1등급"이 아니고 "2등급" 또는 "3등급"인 경우가 있어, 정부가 목표하는 각 가정당 10Mbps, 개인당 2Mbps 고속정보통신 서비스는 실현성 문제점이 있다. 정부의 인증심사 기준에 중앙관리실 장비 등에 대한 것은 심사기준에 누락되어 있고 또 사생활 정보보호를 위한 대응기술, 시스템 준비 정도까지 포함하여 종합적으로 평가한 뒤 인증을 부여하여야 한다는 것이 본인의 연구 초점이다. 사이버 아파트란 광통신을 주축으로 영상과 음성, 데이터를 자유 자재로 전송 처리하는 초고속 정보통신망을 이용하는 것으로 LAN 장비를 이용하여 각 세대간 통신은 물론 누구나 인터넷을 사용할 수 있는 기능이 있는 설계된 아파트를 말한다. 사이버 아파트의 네트워크에는 금융, 홈쇼핑, 예약, 지역정보, 관공서, 의료서비스, 레저 생활정보 등 차별화된 콘텐츠 확보가 필요하다. 본 연구의 핵심은 사이버 아파트의 현 실태와 문제점, 정부의 인증심사 기준의 미비점과 문제점, 사이버 아파트의 기능, 구성요소, 시스템 구축, 서버활용도, 장비들에 관한 것과 그리고 정부의 사이버 아파트 육성정책, 정보보호 대책과 관련업체들의 동향 등을 연구하여 요약 정리하였다.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.409-412
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• 2010

This study investigated and discussed the drying characteristics of municipal wood wastes (wood, particle board, medium density fiber-board(MDF)) in the $N_2$ environment with an isothermal thermogravimetric analyzer. The drying rate could be expressed by a first order reaction model on remaining fraction of moisture. The activation energy ranged from 12.72 kJ/g mol to 18.31 kJ/g mol and the frequency factor from 0.2155 1/s to 1.249 1/s.