• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.242-242
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• 2011

현재 반도체 및 디스플레이 장비들이 공정 매개변수 및 플라즈마 변수를 독립적으로 제어하기 위하여 전원 주파수를 다양하게 사용된다. 플라즈마의 상태나 에너지 전달 효율은 반도체 및 디스플레이 공정에 중요한 요소이다. 따라서 플라즈마 발생장치의 전원 주파수를 바꾸었을 때의 플라즈마 밀도와 에너지 전달 효율에 관하여 연구하였다. 공정용 유도 결합 플라즈마(ICP)를 발생시키기 위하여 신호 발생기에서 전력 증폭기와 임피던스 정합회로(Matcher)를 거쳐 반응 용기에서 플라즈마를 발생시켰다. 6 mTorr의 압력에서 주파수는 13.56 MHz에서부터 80 MHz까지, 15~60 W의 전력을 인가하였다. 플라즈마의 에너지 효율을 측정은 제작한 로고스키코일(Rogowski Coil)을 이용하여 시스템 전반을 등가회로로 계산하였으며, 플라즈마 밀도는 반응용기 중앙에서 부유 탐침법을 적용하여 도출하였다. 같은 전력 조건에서 주파수가 증가함에 따라 플라즈마 밀도가 증가함을 볼 수 있었다. 그러나 플라즈마 에너지 효율은 주파수가 높아짐에 따라 점점 커지다 작아지는 경향을 볼 수 있었다. 에너지 전달 효율의 변화는 정합회로의 표피효과(Skin effect)에 기인하며 플라즈마 밀도의 변화는 이온의 에너지 손실에 기인한다.

• Special Issue of the Society of Naval Architects of Korea
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• 2007.09a
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• pp.128-134
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• 2007

Induction heating process includes magnetic and thermal situations. In order to analyze the induction heating, material properties depending on temperature are considered. In this paper, three dimensional analysis of induction heating process for moving inductor is analyzed using moving coordinate. The skin effect is confirmed inside the steel plate in the electro-magnetic analysis. The heat generation at the initial state is different from that at the quasi-stationary state. Therefore, material properties depending on temperature must be considered. The results of finite element analysis agree well with the experimental temperature results.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.288-290
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• 1997

The electromagnetic theory is applicated on the field of electromagnetic continuous casting(EMC). This paper treats the stream phenomena of high frequency current on the solid-loop coil of which consists the hollow conductor. The governing equation is derived from elctromagnetic field theory and the characteristics are analyzed by FEM. The results may be availabe data on designing the optimum shape of the coil for the improved pinch effect.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.804-806
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• 2000

동일한 임계전류 특성을 갖는 Bi-2223 테이프에 전력기기의 실제 응용에서 발생되는 큰 사고전류를 고려한 임계전류보다 큰 과임계전류를 흘렸을 때 테이프의 온도상승 및 저항 특성을 중요한 인자에 대해 조사하였다. 냉각이 좋은 즉 비절연 테이프의 경우 온도상승은 없고, 표피효과에 의한 저항의 증가도 없고, 특히 비절연 테이프의 경우 과도 및 정상 상태 저항이 동일한 반면 절연 테이프의 경우 매우 상이하고, 전기절연 길이를 전압탭보다 길게만 해주면 길이에 무관하게 온도상승 및 저항이 동일하였으며 마지막으로 모재의 저항율이 상이하여도 임계전류만 동일하면 온도상승 및 저항은 유사함을 알 수 있었다.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.230-231
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• 2002

고주파전류가 통전되고 있는 연자성체에 외부자계가 인가되면 자성체의 표피효과(Skin effect)에 의해서 임피던스가 변화하게 된다. 따라서 고주파의 정전류를 통전시키면 자성체의 양단에서 전압의 크기는 외부에서 인가되는 자계에 따라 변화하게 되는데, 이 때의 전압을 자계로 환산함으로써 자계의 검출이 가능하다. 이러한 현상을 이용하여 자계를 검출하는 소자를 자기임피던스 센서(Magneto-Impedance sensor)라고 한다$^{1.2}$ . 자기임피던스 센서는 주로 연자성이 우수한 아몰퍼스 자성체를 이용하여 구성되고, 구조가 간단하며, 극히 우수한 자계 검출능력을 나타내므로, 차세대의 고감도 자계센서로서 주목을 받고 있다. (중략)

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.407-408
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• 2014

최근 하이브리드 자동차, 지능형 자동차 등을 비롯한 미래형 자동차 분야와 관련된 연구 개발과 맞물려 자동차 전장 회로 시스템은 더욱 복잡해지고 있다. 자동차 전장 시스템의 경향으로 그린카를 들 수 있는데 이에 대한 하나의 방향성은 연비 개선과 최적의 운행조건을 위한 ISG System( Idle Stop & Go system )의 채택으로 가고 있는 추세이다. 여러 장점을 가진 ISG 시스템이지만 시동 모드 시 많은 양의 전류가 순간적으로 흘러가 일순간 전압강하 발생과 높은 스위칭 주파수에 의한 표피효과가 일어난다. 이를 제어하는 기술로 전장회로상의 DC/DC 컨버터 기술이 핵심이라 할 수 있다. 이에 따라 본 논문에서는 확장성이 용이한 고효율 DC/DC 컨버터를 제안하고 모의 실험과 실제 실험을 통해 검토한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.9
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• pp.78-85
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• 2000

A new analytical VLSI interconnect delay model is presented and its accuracy is experimentally verified. In the model, the transmission line parameter variations due to skin effect, proximity effect, and silicon substrate effect are taken into account. That is, the circuit model of the interconnect line that includes these effects is newly developed and analyzed. For the model verification, test patterns combined the coplanar structure with microstrip were designed by using 0.35${\mu}m$ CMOS process technology. It is shown that the accuracy of the model is less than about 10% error.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.263-278
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• 2004

Ursolic acid (UA) and Oleanolic acid (ONA), known as urson, micromerol and malol, are pentacyclic triterpenoid compounds which naturally occur in a large number of vegetarian foods, medicinal herbs, and plants. They may occur in their free acid form or as aglycones for triterpenoid saponins, which are comprised of a triterpenoid aglycone, linked to one or more sugar moieties. Therefore UA and ONA are similar in pharmacological activity. Lately scientific research, which led to the identification of UA and ONA, revealed that several pharmacological effects, such as antitumor, hepato-protective, anti-inflammatory, anticarcinogenic, antimicrobial, and anti-hyperlipidemic could be attributed to UA and ONA. Here, we introduced the effect of UA and ONA on acutely barrier disrupted and normal hairless mouse skin. To evaluate the effects of UA and ONA on epidermal permeability barrier recovery, both flanks of 8-12 week-old hairless mice were topically treated with either 0.01-0.1mg/mL UA or 0.1-1mg/mL ONA after tape stripping, and TEWL (transepidermal water loss) was measured. The recovery rate increased in those UA or ONA treated groups (0.1mg/mL UA and 0.5mg/mL ONA) at 6h more than 20% compared to vehicle treated group (p < 0.05). Here, we introduced the effects of UA and ONA on acute barrier disruption and normal epidermal permeability barrier function. For verifying the effects of UA and ONA on normal epidermal barrier, hydration and TEWL were measured for 1 and 3 weeks after UA and ONA applications (2mg/mL per day). We also investigated the features of epidermis and dermis using electron microscopy (EM) and light microscopy (LM). Both samples increased hydration compared to vehicle group from 1 week without TEWL alteration (p < 0.005). EM examination using RuO4 and OsO4 fixation revealed that secretion and numbers of lamellar bodies and complete formation of lipid bilayers were most prominent (ONA=UA > vehicle). LM finding showed that thickness of stratum corneum (SC) was slightly increased and especially epidermal thickening and flattening was observed (UA > ONA > vehicle). We also observed that UA and ONA stimulate epidermal keratinocyte differentiation via PPAR Protein expression of involucrin, loricrin, and filaggrin increased at least 2 and 3 fold in HaCaT cells treated with either ONA (10${\mu}$M) or UA (10${\mu}$M) for 24 h respectively. This result suggested that the UA and ONA can improve epidermal permeability barrier function and induce the epidermal keratinocyte differentiation via PPAR Using Masson-trichrome and elastic fiber staining, we observed collagen thickening and elastic fiber elongation by UA and ONA treatments. In vitro results of collagen and elastin synthesis and elastase inhibitory activity measurements were also confirmed in vivo findings. These data suggested that the effects of UA and ONA related to not only epidermal permeability barrier functions but also dermal collagen and elastic fiber synthesis. Taken together, UA and ONA can be relevant candidates to improve epidermal and dermal functions and pertinent agents for cosmeseutical applications.

• Journal of Digital Convergence
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• v.12 no.6
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• pp.407-414
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• 2014

The aim of this study was to evaluate the photodynamic therapy effects against staphylococci using Photofrin and Radachlorin with Light emitting diode(LED). Experimental methods, The bacterial suspensions containing Staphylococcus aureus and Staphylococcus epidermidis at $1{\times}10^5$ were prepared and diluted to different concentrations of photosensitizer, Photofrin or Radachlorin, on 1.25, 2. 5,5 and $10{\mu}g/ml$. The bacterial suspensions were exposed to 630 and 670 nm LED light at the energy density of 14.4 and $19.8J/cm^2$, respectively. The CFU results of S. aureus and S. epidermidis were showed 33 and 50 colony forming at $5{\mu}g/ml$ of Photofrin, respectively and both of them perfectely were dead at $5{\mu}g/ml$ of Radachlorin. The fluorescent intensity by flow cytometry was showed the increase in the dead cells than the normal cells. In the TEM photograph, the damage of bacterial membrane and the distortion of cell morphology were observed. These results suggest that photodynamic therapy combine with Photofrin and Radachlorin can be applied a new modality for antibacterial therapy.

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.77-85
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• 2021

Glucosylceramides (GluCer) are known to play an important role in both water retention and epidermal permeability barrier function in the mammalian stratum corneum. In this study, we investigated the effects of pineapple fruit extract containing glucosylceramides (PFEG) on the maintenance and recovery of skin barrier function using atopic dermatitis-induced animal models. Five-week-old male Hos:HR-1 mice were divided into four groups fed on standard diet, unsaturated fatty acids-deficient (HR-AD) diet, and HR-AD diet supplemented with 0.01% or 0.1% pineapple-GluCer. Skin barrier function was evaluated by transepidermal water loss (TEWL), dermal moisture content, moisture content of the stratum corneum and wrinkle formation. The control group (HR-AD administration group) showed increased transepidermal water loss (TEWL), while the epidermal moisture content and the moisture content of the stratum corneum slowly decreased. However, in the PFEG groups (with 0.1% or 0.01% glucosylceramide), the TEWL levels were significantly reduced at 2 weeks. The PFEG also helped maintain skin moisturizing function by significantly suppressing the decrease of the epidermal moisture content and the moisture content of the stratum corneum. These results show that the PFEG is effective for maintaining and improving the function of the skin barrier. Therefore, this study suggests that PFEG is a potential candidate material for skin functional foods.