• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.600-601
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• 2008

국내에서 CBP전력시장이 운영된지 벌써 7년이 흘렀다. 그간 많은 개선을 통해 한국 전력산업의 고유 특성을 반영한 전력시장으로 발전해왔다. 타 산업에서의 시장과 달리 실시간으로 발생하는 전력계통의 제약을 반영하면서 수많은 데이터를 처리해야하는 특성으로 인해 전력시장은 IT기술의 발전과 동행해 왔다고 할 수 있다. 특히 이렇게 복잡한 실시간 시장을 감시하고 분석할 수 있는 기법 및 IT시스템은 전력시장을 운영하는 모든 나라에서 지속적으로 발전해왔으며, 향후에도 계속 발전해 갈 것이다. 우리나라도 이제 안정단계에 접어든 전력시장을 더욱 발전시키기 위해서는 전력시장을 감시하고 분석할 수 있는 다양한 기법 및 IT시스템의 발전이 필수적일 것이다. 이러한 관점에서 이번 전력거래소에서 구축한 전력시장 종합분석시스템은 우리나라의 전력시장 발전에 커다란 의미가 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1024-1034
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• 1998

Most public cryptosystem widely used in communication network are based on the exponentiation-arithmetic. But, cryptosystem has to use bigger and bigger key parameter to attain an adequate level of security. This situation increases both computation and time delay. Montgomery, yang and Kawamura presented a method by using the pre-computation, intermediately computing and table look-up on modular reduction. Coster, Brickel and Lee persented also a method by using the pre-computation on exponentiation. This paper propose to reduce computation of exponentiation with spare prime. This method is to enhance computation efficiency in cryptosystem used discrete logarithms.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.449-450
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• 2018

가상현실(VR) 기술을 활용한 가상직무체험은 실제 업무 경험과 유사한 경험을 습득할 수 있기 때문에 기존 e-러닝 및 동영상 교육에 비해 학습몰입도와 효과가 뛰어나다. 그러므로 한국전력공사에서는 (주)포미트와 함께 접근이 어렵고 위험한 작업이 많은 변전설비의 정비를 위한 가상현실(VR) 교육콘텐츠를 제작하였다. 가상현실(VR) 기술이 적용된 교육콘텐츠의 경우 교수내용의 적정성 및 효과성 외에도 반복/장기 학습이 가능하도록 하기 위하여 콘텐츠의 화질, VR 멀미를 최소화 할 수 있는 초당 프레임 수 등 학습자 관점에서의 기술 적용에 대한 연구가 필요하다. 하여 본 연구에서는 "변전설비 정밀점검 절차 교육콘텐츠"를 대상으로 가상현실(VR) 교육콘텐츠의 구현 방법에 대해 서술하고자 한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.89-90
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• 2021

본 논문에서는 Python과 Selenium 라이브러리 기반의 재난 문자 크롤링 및 데이터 시각화 애플리케이션을 설계하고 구현한다. 이 애플리케이션의 특징은 웹상에서 재난 문자 데이터를 크롤링(Crawling)하여 그 빈도수에 따라 시각화하는 것이다. 이 애플리케이션을 활용하여 국민재난안전포털에 접속하여 재난 문자 데이터를 크롤링하고, 그 데이터를 Word Cloud를 활용하여 지역별 재난 문자 빈도수를 시각화한다. 지역별 재난 문자 빈도수를 한눈에 보기 쉽게 시각화함으로써 재난문자를 잘 확인하지 않는 사람들에게 해당 지역의 재난 정보를 쉽게 전달하는 기능을 제공한다.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.52-59
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• 2008

The geometric design of an implant surface may play an important role in affecting early osseointegration. It is well known that the porous surfaced implant had much benefits for the osseointegration and the early stability of implant. However, the porous surfaced implant had weakness from the transgingival contamitants, and it resulted in alveolar bone loss. The other problem identified with porous surface implant is the loss of physical properties resulting from the bead sintering process. In this study, we developed the new bead coating implant to overcome the disadvantages of porous surfaced implant. Ti-6Al-4V beads were supplied from STARMET (USA). The beads were prepared by a plasma rotating electrode process (PREP) and had a nearly spherical shape with a diameter of 75-150 ${\mu}m$. Two types of titanium implants were supplied by KJ Meditech (Korea). One is an external hexa system (External type) and the other is an internal system with threads (Internal type). The implants were pasted with beads using polyvinylalcohol solution as a binder, and then sintered at 1250 $^{\circ}C$ for 2 hours in vacuum of $10^{-5}$ torr. The resulting porous structure was 400-500 ${\mu}m$ thick and consisted of three to four bead layers bonded to each other and the implant. The pore size was in the range of 50-150 ${\mu}m$ and the porosity was 30-40 % in volume. The aim of this study was to evaluate the osseointegration of the newly developed dental implant. The experimental implants (n=16) were inserted in the unilateral femur of 4 mongrel dogs. All animals were killed at 8 weeks after implantation, and samples were harvested for hitological examination. All bead coated porous implants were successfully osseointegrated with peripheral bone. The average bone-implant contact ratios were 84.6 % (External type) and 81.5 % (Internal type). In the modified Goldner's trichrome staining, new generated mature bones were observed at the implant interface at 8 weeks after implantation. Although, further studies are required, we could conclude that the newly developed vacuum sintered Ti-6Al-4V bead coating implant was strong enough to resist the implant insertion force, and it was easily osseointegrated with peripheral bone.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.3
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• pp.209-215
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• 2006

Preoperative neoadjuvant chemotherapy using cisplatin and 5-FU is generally given in oral and maxillofacial cancer. At tissue level both inflammation and fibrosis occur after chemotherapy. The cellular changes mimic those of a granulating wound, with activated macrophages and fibroblasts replacing the malignant cells as they are erradicated. Stromal cells, together with extracellular matrix components, provide the microenvironment that is pivotal for tumor cell growth, invasion, and metastatic progression. Vascular endothelial growth factor(VEGF), an important regulator of angiogenesis in cancer, induces mitogenesis of vascular endothelial cells, and vascular permeabilization and microvessel formation in a tumor are associated with tumor nutrition and oxygenation. Also, they are associated with chemotherapeutic drug delivery. Oxygen delivery to tumor appears to rely on a network of microvessels, On the other hand, the tumor microvessel is clearly an important factor in chemotherapeutic drug delivery to cancer cells, and the efficacy of drug delivery can be high in richly vascularized tumors. So, this study was conducted to evaluate the effect of neoadjuvant chemotherapy on microvessel density from 11 patients with tongue cancers. Our results showed that neoadjuvant chemotherapy was seemed to decrease VEGF expression in tumor cells, however, it did not significantly alter VEGF expression in tumor-associated macrophages. Also, Neoadjuvant chemotherapy had little effect on the microvessel density using CD34, and tumor-associated macrophage level using CD68. Thus, tumorassociated macrophages seem to be the key factor associated with the maintenance of microvessel density after neoadjuvant chemotherapy in tongue cancer.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.4
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• pp.331-339
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• 2007

Background: Distraction osteogenesis(DO) is a useful method for treating cases demanding the generation of new bone. During DO, the angiogenic activity is crucial factor in the new bone formation. The aim of this study was to detect the autocrine growth activity in the cellular components of the distracted bone with observation of the co-expression of vascular endothelial growth factor(VEGF) and its receptors following the mandibular DO. Materials and methods: Unilateral mandibular distraction(0.5 mm twice per day for 10 days) was performed in six mongrel dogs. Two animals were killed at 7, 14, and 28 days after completion of distraction, respectively. Immediately after the animals were killed, the right mandibles were harvested en block. Immunohistochemical staining was processed for observation of the VEGF expression, and double immunofluorescent staining was also processed for detection of the co-expression of osteocalcin and VEGF's two distinct receptors(VEGFR-1 and VEGFR-2). Results: At 7 and 14 days after distraction, the expressions of VEGF were significantly increased in the osteogenic cells of the distracted bone. Up to 28 days after distraction, VEGF was still expressed moderate in the osteoblastic cells of distracted bone. The co-expressions of osteocalcin/VEGFR-1 and osteocalcin/VEGFR-2 were observed in the distracted bone at 7 and 14 days after distraction. In the double immunofluorescent staining, the co-expression' s level of osteocalcin/VEGFR-1 was more than that of osteocalcin/VEGFR-2. Conclusion: Taken together, this study suggested that VEGF plays an important role in the osteogenesis, and these osteoblastic cell-derived VEGF might act as autocrine growth factor during distraction osteogenesis. In the other word, the cellular components, such as osteoblasts and immature fibroblast-like cellsor mesenchymal cells in the distracted bone, might have autocrine growth activity during distraction osteogenesis.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.6
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• pp.528-534
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• 2005

Angiogenesis is important for the growth and metastasis of solid tumors. Some growth factors, inflammatory cytokines, and angiogenin are known to promote tumor angiogenesis. Among them, Vascular endothelial growth factor (VEGF) is the most intriguing factor in regard to tumor angiogenesis. Inhibition of VEGF activity by neutralizing antibodies or by the introduction of dominant negative VEGF receptors into endothelial cells of tumor-associated blood vessels resulted in the inhibition of tumor growth and in tumor regression, indicating that VEGF is a major initiator of tumor angiogenesis. VEGF promotes angiogenesis through their receptors, Flt-1 and Flk-1/KDR. on vascular endothelial cells. These two receptors were usually believed to be expressed specifically on vascular endothelial cell. Several reports have now shown that VEGF is not only significantly associated with microvessel density but also has prognostic value in both node-negative and node-positive oral squamous cell carcinoma. For many years several histologic features of the neoplasms are being considered when assessing the influence of malignancy grading on recurrence and prognosis. Among the characteristics investigated, degree of keratinization, nuclear pleomorphism, mode of invasion, microscopic depth of invasion, intravascular invasion, lymphocyte infiltration, and number of mitoses have been considered as important prognostic factors. So, this study was conducted to evaluate the correlation of vascular endothelial growth factor expression with malignancy in paraffin-embedded biopsy specimens from 11 patients with tongue cancers. Our results showed that high immunoreactivity specimens of VEGF expression were significantly lower keratinization degree and more pronounced nuclear pleomorphism than in low immunoreactivity specimens. Thus, VEGF expression could be used as a prognostic marker in tongue cancer.

• Journal of Korean society of Dental Hygiene
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• v.15 no.3
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• pp.523-529
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• 2015

Objectives: Oropharynx tumors(oral cancer), are caused by tobacco, alcohol consumption, and high-risk human papillomavirus(HPV) infection. Oral squamous cell carcinoma(OSCC) is the most common type of oral cancer and frequently arises from the mucosa of the oropharynx and oral cavity. Despite advances in the diagnosis and treatment(chemotherapy, radiotherapy, and surgery) of oral cancer, over the past two decades, the overall survival rates remains at about 60%. Methods: We pretreated HSC-2 cells with various doses of exposed the cells to eugenol and then we measured cell viability by MTT assay. Results: Cell proliferation was markedly inhibited after eugenol treatment compared to the control. The majority of HSC-2 cells in the control groups showed normal morphology with round regular nuclei. In contrast, apoptotic bodies were seen in the 0.5 mM, 1 mM, 2 mM group. However, the pretreatment with eugenol increased HSC-2 cells apoptosis according to dose-dependency. PI staining quantitatively confirmed the anti-apoptotic effects of propofol. The expression levels of cleaved caspase 3, and Bak significantly increased in HSC-2 cells. Conclusions: These findings indicate that eugenol could be a potential anti-cancer agent for human OSCC and provide valuable data for the development of a novel anticancer strategy.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.2
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• pp.132-136
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• 2000

The cell surface glycoprotein CD44 is a kind of adhesion molecule, which binds hyaluronic acid, type I collagen and fibronectin. Although there have been numerous reports on the expression and the function of CD44 in lymphocytes and macrophages, very little is known about its distribution and definite role in epithelial tissue, especially in oral epithelial one. The present study was performed to investigate the distribution and expression of the CD44 in human gingiva and squamous cell carcinoma(SCC) arising in human gingiva. And the authors compared CD44 expression with histopathologic grade of SCC. The results were as follows: 1. The CD44 was strongly expressed in granular, spinous and basal layers of normal marginal and attached gingiva, in spinous and basal layers of normal sulcular gingiva, and in all epithelial layers of normal junctional gingiva. 2. In SCC of gingiva, the CD44 was expressed in all but one case. In most of the cases the CD44 was expressed at cell membrane and the degree of expression was relatively strong. 3. In low-grade SCC of gingiva, the CD44 was strongly expressed, especially at the basal and spinous layers of abundantly keratinized cancer nests. In high-grade SCC of gingiva, the CD44 expression tended to be weak but was strong at cells showing individual keratinization. This study suggest that the CD44 expression of normal and cancerous gingival epithelium is associated with the degree of proliferation and differentiation of epithelial cells.