• 전기학회논문지P
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• 제63권4호
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• pp.373-377
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• 2014

A cross linked polyethylene (XLPE) material has been widely used to develop a distribution power cable due to its excellent electrical characteristics and mechanical strength. However, several problems such as environmental disruption, electrical aging, thermosetting property, and impurities which cause degradation also arise. Therefore, a novel dielectric material should be developed to substitute for the XLPE. Several kinds of polyolefin materials to substitute for the conventional dielectric material, XLPE are developed and A cylindrical rod to cylindrical rod electrode system made with stainless steel is used to perform the experiments according to the ASTM D-149 protocol under an AC and Impulse input voltage condition. The experimental results are calculated by the Weibull distribution method and analyzed by an Finite Element Method(FEM). Finally, the dielectric characteristics of the conventional XLPE and novel polyolefin are experimented compared with each other in this study.

• Journal of Ginseng Research
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• 제36권1호
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• pp.68-77
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• 2012

In this study, we investigated the protective effects of processed Panax ginseng, sun ginseng (SG) against the UVB-irradiation on epidermal keratinocytes and dermal fibroblasts. Pretreatment of SG in HaCaT keratinocytes and human dermal fibroblasts reduced UVB-induced cell damage as seen by reduced lactate dehydrogenase release. We also found that SG restored the UVB-induced decrease in anti-apoptotic gene expression (bcl-2 and bcl-xL) in these cells, indicating that SG has an anti-apoptotic effect and thus can protect cells from cell death caused by strong UVB radiation. In addition, SG inhibited the excessive expression of c-jun and c-fos gene by the UVB in HeCaT cells and human dermal fibroblasts. We also demonstrated that SG may exert an anti-inflammatory activity by reducing the nitric oxide production and inducible nitric oxide synthase mRNA synthesis in HaCaT keratinocytes and human dermal fibroblasts. This was further supported by its inhibitory effects on the elevated cyclooxygenase-2 and tumor necrosis factor-${\alpha}$ transcription which was induced by UVB-irradiation in HaCaT cells. In addition, SG may have anti-aging property in terms of induction of procollagen gene expression and inhibition of the matrix metalloprotease-1 gene expression caused by UVB-exposure. These findings suggest that SG can be a potential agent that may protect against the dermal cell damage caused by UVB.

• 한국표면공학회지
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• 제29권5호
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• pp.345-349
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• 1996

The wetting property of polymer surfaces is very important for practical applications. Plasma source ion implantation technique was used to improve the wetting properties of polymer surfaces. Poly(ethylene terephtalate) and other polymer sheets were mounted on the target stage and an RF plasma was generated by means of an antenna located inside the vacuum chamber. High voltage pulses of up to -10kV, 10 $\mu$sec, and up to 1 kHz were applied to the stage. The samples were implanted for 5 minutes with using Ar, $N_2,O_2,CH_4,CF_4$ and their mixture as source gases. A contact angle meter was used to measure the water contact angles of the implanted samples and of the samples stored in ambient conditions after implantation. The modified surfaces were analysed with Time-Of-Flight Mass Spectrometer (TOF-SIMS) and Auger Electron Spectroscopy (AES). The oxygen-implanted samples showed extremely low water contact angles of $3^{\circ}C$ compared to $79^{\circ}C$ of unimplanted ones. Furthermore, the modified surfaces were relatively stable with respect to aging in ambient conditions, which is one of the major concerns of the other surface treatment techniques. From TOF-SIMS analysis it was found that oxygen-containing functional groups had been formed on the implanted surfaces. On the other hand, the $CF_4$-implanted samples turned out to be more hydro-phobic than unimplanted ones, giving water contact angles exceeding $100^{\circ}C$ . The experiment showed that plasma source ion implantation is a very promising technique for polymer surface modification especially for large area treatment.

• 한국산학기술학회논문지
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• 제16권6호
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• pp.4298-4307
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• 2015

최근 콘크리트 구조물의 내구성 저하에 따른 성능저하로 유지 보수나 보강등에 상당한 비용이 증가함에 따라 콘크리트의 고유 특성인 균열 저감에 대한 연구가 필요한 실정이다. 특히 장기간 운영에 따른 지하 전력구의 노후화로 유지 보수에 어려움이 상존함에 따라 전력구 설계단계에서 균열을 획기적으로 저감할 수 있는 저수축 콘크리트용 수축저감제 기술 개발이 필요하다. 본 연구는 콘크리트 구조물의 내구성 저하에 따른 균열을 방지하고자 균열을 획기적으로 저감할 수 있는 저수축 콘크리트를 개발하기 위한 것으로 수축저감 물질을 선정하고 모르타르 및 콘크리트 특성을 검토한 결과 클리콜계의 경우 압축강도 특성 및 건조수축 길이변화 실험결과에서 우수한 것으로 나타나 수축저감제로서의 가능성을 확인하였다. 추후 수축저감제의 범용적인 적용성 검토를 위하여 수축저감제의 사용량 및 사용재료 변화 등에 대한 다양한 재료변수 요인 검토를 통하여 수축저감제의 성능 검토가 필요할 것으로 사료된다.

• 한국운동역학회지
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• 제24권4호
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• pp.399-415
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• 2014

The aim of this study was to investigate the effect of resistance training with and without whole-body vibration(WBV) on the biomechanical properties of the plantarflexor in the elderly women (>60 yrs., n=35). Thirty-five volunteers were randomly assigned to a resistance training with WBV group (RVT, n=14), a resistance training without WBV (RT, n=11), and a non-training control group (CON, n=10). The RVT and the RT groups participated in the training sessions three times a week for 8 weeks, followed by a 4-week detraining period. The CON group was instructed to refrain from any type of resistance training. To assess strength and activation of the plantarflexor muscles, maximum isometric ankle plantarflexion torque and muscle activation of the triceps surae muscles were measured using dynamometry, twitch interpolation technique and electromyography at four different ankle joint angles. Also, the lower extremity function was assessed by vertical jumping. The measurements were performed prior to, 2 and 8 weeks after the training and after a 4-week detraining period. Following the 8-week training sessions, an increase in the isometric plantarflexion strength was found to be greater for the RVT compared with the RT group (p<.05). Muscle inhibition was significantly decreased after training than before training only for the RVT (p<.05). Following the detraining period, a decrease in isometric plantarflexors strength and a increases in muscle inhibition were significantly less in the RVT compared with the RT group. In conclusion, the exercise with WBV is a feasible training modality for the elderly and seems to have a boosting effect when used with conventional resistance training.

• 한국도로학회논문집
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• 제1권2호
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• pp.121-133
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• 1999

본 논문은 국내 정유사에서 생산되는 도로 포장용 아스팔트에 대하여 노화에 따른 거동 특성을 파악하였다. 이를 위해 국내의 5개 정유회사에 생산되는 두가지 등급의 아스팔트 제품(침입도 85-100, 침입도 60-70)을 포함한 총 9종에 대하여 노화 단계별(노화 이전, 단기노화, 장기노화)로 국내 스트레이트 아스팔트의 침입도$(25^{\circ}C)$, 점도$(50^{\circ}C\;135^{\circ}C)$, 연화점, 및 DSR 시험$(-20^{\circ}C\sim30^{\circ}C)$을 수행하여, 아스팔트의 물성 변화 특성을 고찰하였다. 연구 결과, 국내 스트레이트 아스팔트의 거동은 고온($60^{\circ}C$근방) 및 상온$(10-30^{\circ}C)$범위에서 정유사 제품에 따라 상당한 차이를 나타내었으며, 저온의 경우에는 정유사 제품이나 등급에 관계없이 거의 유사한 거동을 나타내었다. 따라서 어느 정유사의 아스팔트를 사용하는가에 따라, 저온에서의 온도 균열에 대한 저항성은 다소 비슷한 수준일 것으로 판단되지만, 소성변형 및 피로 균열에 대한 저항성이 상이하게 나타날 것으로 판단된다.

• 의료법학
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• 제13권1호
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• pp.125-153
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• 2012

The adult guardianship system has been introduced through amendments of Korean Civil Code for the first time in the March 2011(Act No. 10429, 7. 1. 2013. enforcement). The adult guardianship system has the main purposes to provide a lot of help vulnerable adults and elderly, and protect them on the welfare related with property act, treatment, care, etc. There could be a controversy about whether the protection Legal Guardian's consent(formerly known as the Mental Health Act) or permission of the Family Court(revised Civil Code) are required to, or the Mental Health Act should be revised, when mental patient will be hospitalized forcibly. The author proposes that mental patient with Adult guardians should be determined by Legal Guardian's consent and approval of the Family Court, but mental patient without Adult guardians could be determined by Legal Guardian's consent. The issue of Withdrawing of life-sustaining treatment could be occurred due to the aging society and the development of modern medicine, and this has provided difficult, various problems to mankind in Legal, ethical, and social welfare aspects. The need of Death with dignity law or Natural death law has been reduced for a revision of the Civil Code. Therefore, on the issue of Withdrawing of life-sustaining treatment, in the future, intervention of the court is necessary in accordance with the revised Civil Code Section, and Organ Transplantation Act and the brain death criteria may serve as an important criterion.

• 산업경영시스템학회지
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• 제38권4호
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• pp.184-192
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• 2015

Korea has already entered into an aging society. In recent decades, the health problems for seniors has received considerable interest. We often see the elderly who have been struggled from discomfort or illness of the foot. Those foot related problems mainly cause from the use of improper shoes. Recently, shoe makers sell the shoes for seniors, so called comfort shoes, but the shoes are too expensive for seniors to buy easily. In this paper, we develop cheap insoles for seniors as an alternative of the comfort shoes and suggest the systematic process for the insoles development. This systematic process is as follows: 1) Survey the literature about the market of insole, 2) Investigate the standard size of body and foot for the seniors in Korea, 3) Analyze the customer needs by survey, 4) Study the walking pattern by experiments, and 5) Develop the novel insole for the seniors to relieve the inconveniences related with foot. From the newly developed insoles, the company B gains the sales increasing effect approximately 30% over through the increase in consumer satisfaction and company reputation and secures for intellectual property rights. Using the database from Korea Research Institute of Standards and Science, the reliability of developing technology of the functional insole has been obtained. The seniors are also enable to choose an alternative of comfort shoes for foot health. In the future, the insoles developed from this study have wide applications in the medical, cosmetic fields, and leisure sports fields. Accordingly, it seems to require more systematic studies utilizing Walk Analyzer and Foot Pressure Meter.

• Elastomers and Composites
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• 제33권4호
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• pp.281-289
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• 1998

4종류의 고무 즉, 천연고무(NR), styrene-butadiene copolymer(SBR), ethylene-propylene diene monomer(EPDM), brominated isobutylene-p-methyl-styrene copolymer(BIMS)의 영(Young) 탄성율을 비롯한 인장특성과 인열강도를 여러가지 가교도와 시험온도에서 측정하였다. 과가황(over-cure)의 영향을 조사하기 위해 과가교 고무컴파운드의 인장강도와 팽윤(swelling) 거동도 조사하였다. 모든 고무컴파운드에 대해 영 탄성율(E)은 가교도와 선형적인 비례관계를 보였다. EPDM이 가장 높은 기울기를 그리고 BIMS가 가장 낮은 기울기를 보였고, NR과 SBR은 이들 사이의 값을 나타내었다. 인열강도 Gc는 NR>BIMS>SBR>EPDM의 순으로 나타났다. 과가교에 따라 NR과 SBR의 가교도는 감소한 반면, BIMS는 오히려 증가하였고, EPDM은 거의 변하지 않았다.

• Elastomers and Composites
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• 제49권2호
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• pp.95-102
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• 2014

최근 공동주택의 층간 소음으로 인하여 사회적 문제가 크게 대두되고 있다. 본 연구에서는 소음 차단 성능을 향상시키기 위해 바닥 진동 제어 시스템에 적용되어질 방진고무를 제조하였다. 다양한 유형의 고무 중 우수한 노화특성, 낮은 반발탄성 및 높은 댐핑특성의 성질은 갖는 부틸 고무를 방진고무의 원료 고무로 선정하였다. 그리고 부틸 컴파운드에 첨가되는 카본블랙의 유형과 함량에 따른 방진고무의 물성을 확인하였다. 표면적이 큰 카본블랙을 사용하거나 함량이 증가할수록 고무와 카본블랙간의 결합고무의 함량이 증가하여 높은 기계적 물성, 낮은 반발탄성과 높은 댐핑특성을 나타내었다. 연구 결과를 토대로 최적의 카본블랙 종류와 함량을 결정하고 방진고무를 제조한 뒤 바닥진동제어 시스템에 적용하였다. 바닥충격음을 측정한 결과 경량충격음 40 dB, 중량충격음 43 dB을 나타내어 소음차단 성능이 우수한 것을 확인할 수 있었다.