• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.26 no.5
• /
• pp.490-496
• /
• 2000

We have conducted a retrospective study of 224 patients with the diagnosis of oral and maxillofacial infection who had been treated between 1988 and 1999 at Gyeong-Sang National University Hospital. This study was aimed to furnish the data of oral and maxillofacial infection and to aid diagnosis and treatment. The most common fascial space involved, as determined by clinical, radiologic, and operative findings, were the submandibular space(39.4%). The most frequent cause of oral and maxillofacial infection was odontogenic 68.8%. In the odontogenic cause, dental caries was the most common cause. Two-hundred three patients required surgical drainage of the abscess. Seventeen patients needed tracheostomy for airway control. The overall mortality was 0.9% despite aggressive anti-microbial therapy and early surgical intervention. All other patients had an uneventful recovery without major complication except osteomyelitis case(6.0%). The combination of early radiologic diagnosis, effective antimicrobial therapy, and intensive surgical management contributed to the good prognosis.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.7 no.2
• /
• pp.341-348
• /
• 1997

X-ray diffraction patterns of Pt/Co modulated films prepared by RF comagnetron sputtering method was investigated. Modulated films ([$Pt10.7\AA/Co2.8{\AA}{\times}{12}$]) were deposited on glass substrate with various sputtering conditions : sputtering with variations of gas pressures, sputtering with Xe instead Ar gas, and etching of the buffer layers. In order to obtain the structural information of Pt/Co modulated films, the structural model was constructed and calculated data of the model were compared with experimental ones. Comparison results showed that there were good agreements in satellite peak position and its intensity between them. This suggests that the realistic Pt/Co modulated film can be reproduced by our structure model.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.23 no.1
• /
• pp.81-88
• /
• 2013

As social network service(SNS) has grown rapidly, the variety information being shared through SNS. However, the privacy of individuals can be violated due to the shared information through a SNS or the post written in the past at the SNS. Although, many researches concerned about it, they did not suggest key management and access control especially. In this paper, we propose the method for the protection of the message in SNS using access control and hash-chain.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.8C
• /
• pp.838-848
• /
• 2005

Most of the national critical key infrastructure, such as power, piped gas and water supply facilities, or the high-speed railroad, is run on the SCADA system. Recently, concerns have been raised about the possibility of these facilities being attacked by cyber terrorists, hacking, or viruses. Thus, it is time to adopt the relevant security management techniques. This paper attempts to propose such security management techniques, including information protection measures and troubleshooting, based on a risk analysis process concerning assets, threats/vulnerability, and hazards, and to examine the security management status of critical key infrastructure in the U.S. and Japan.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.5
• /
• pp.1266-1273
• /
• 1996

The nice concept of undeniable signatures was presented by Chaum and van Antwerpen. Briefly, an undeniable signature is signature which cannot be verified withoug the help of the signer. They are therefore less personal than ordinary signatures in the sense that a signature cannot be related to the signer without his help. On the other hand, the signer can only repudiate an alleged signature by proving that it is incorrect. Boyar, Chaum, damgard and Pedersen introduce convertible undeniable signatures. In this schemes, release of a single bit string by the signer turns all of his signatures, which were originally undeniable signatures, into ordinary digital signatures. And, S.J.Kim, S.J.Park and D.H.Won propose a new kind of signature scheme, called "nominative signatures:, that is the dual scheme of undeniable signatures. nominative signatures acheieve theses objectives:Only nominee can verify the nominator(signer)' signature and if necessary, only nominee can prove to the third party that the signature is issued to him(her) and is valid. In this paper we present an efficient integrated system of nominative signatures and (convertible) undeniable signatures. i.e. we show how nominative signature scheme can be changed into a (convertible) undeniable signatures.ures.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.51 no.4
• /
• pp.169-174
• /
• 2002

The magnitude and phase of the compensating voltage in Dynamic Voltage Restorer (DVR) system depend on the voltage sag in the phases affected by the fault and on the influence of the zero sequence components. If the delta connection of the transformer is used, the zero sequence components do not appear on the load side. But nowadays, Y connected transformers with grounded neutral, that is 3-phase 4-wire system, are usually used. Therefore the zero-sequence components are occurred during faults. The zero-sequence components result in the high insulation costs and the asymmetry of the phase and magnitude of the terminal voltages. In this paper 3 phase 4 wire distribution system and 3 phase 3 wire system are analyzed and characteristics of voltage sag are presented. And this paper proposes the method that can mitigate the zero-sequence under the unbalance faults causing voltage sage and phase angle iumps.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2652-2654
• /
• 2004

홈 네트워크나 가로등 제어에 가장 적합한 솔루션 중 하나가 전력선 통신기술이다. 전력선 통신의 사용 주파수 대역은 $50kHz{\sim}450kHz$으로, 이 주파수 대역은 잡음이 매우 많이 존재한다. 또한 시공간에 따른 변화의 요인이 많이 존재하기 때문에 채널 모델링이 매우 어려운 실정이며, 이를 극복할 수 있는 방안으로 영교차점을 이용한 전력선 모뎀을 설계하고자 한다. 변조 방식은 Chirp 심볼을 사용하고, 주파수 대역은 $100kHz{\sim}400kHz$를 사용하였다. 전력선 채널로부터 정보를 획득하기 위해서 효율적인 수신기 구조를 채택하였다. 즉 채널 상황에 적응이 가능하고, 상관에 필요한 필터의 계수를 들어오는 심볼로부터 구하는 방법으로, 다음에 들어오는 심볼과의 상관값을 구하여 정보 신호를 판별하는 형태로 구성하였다. 영교차점을 기준으로 신호를 송수신하는 형태를 취했으며, 영교차점 기준에 들어오는 잡음은 chirp의 대역 확산 특성에 의해서 억제될 수 있다. 이런 기술에 의해서 견실한 전력선 통신 모뎀구현이 가능하였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.1
• /
• pp.25-31
• /
• 2001

The titanium miniplate osteosynthesis system has been used for fixation of bone fragments in the maxillofacial areas due to easy manipulation and even has been proposed for unnecessity of miniplate removal because of the biocompatibility and the corrosion resistance. But recently, there have been some suggestions for its removal, on the basis of findings that there have been pigmentations around the adjacent tissues during miniplate removal procedure and they are the depositions of metal particles. Purposes of this study are to ascertain the presence and nature of pigmentation observed within tissues adjacent to titanium miniplate, and to suggest possible causes of it. We could observe the black pigmentation during miniplate removal procedure for recent about 1.5 year. Pigmented tissues were stained with hematoxylin-eosin(H-E) for light microscophic(LM) examination to investigate the black pigmentations and the histomorphology around them. The scanning electron microscopy(SEM) with energy dispersive X-ray(EDX) analysis was used to examine the ultrastructural nature of pigmentations. Many metal particles with variable sizes and shapes were seen in the connective tissue by SEM and were identified as titanium by EDX.

• Asian Journal of Turfgrass Science
• /
• v.3 no.2
• /
• pp.89-94
• /
• 1989

Research was conducted to obtain t he optimum treatment Of sodium hypochlorite(NaOC I) at various temperatures in t he seed scarification for stimulating germination of zoysiagrass (Zocysia Japonica Steud ) seed. Morphological changes of seed coat were also examined by scanning electron micros cop(SEM). l. Differences in temperature of scarification with 2 .4% NaOCI showed little influence on promoting germination of seeds but seeds treated with 1% solution at l5˚C germinated less than that of higher temperatures. The promotion effect of 4% solution on germination was diminished when seeds were treated for 8 hours of more. The most favorable seed scarification unaffected hy temperature for enhancing germination was 4-6hours treatment at 4% solution in fresh seeds. 2. $GA_3$, treatment did not enhance germination of water-pretreated control seeds hut germination of seeds pretreated with NaOCI l was increased additional 10% or more hy$ GA_3$, Water pretreated control seeds treated with 50 mM hydrogen peroxide(H'O )germinated about 44%. In NaOCI treated seeds. $H_2$$O_2$ treatment increased germination additional l 0% or more. 3. NaOCI l and KOH treatment softened the seed coat and formed the pores hy removing the scab-like thikenings attached to the seed surface. These results suggest that the modes of action of NaOCl in the promotion of seed germination reside in it increase of the permeability of the seed coat, and in the provision of additional oxygen to the seed.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.2 s.34
• /
• pp.159-167
• /
• 2005

Through the increment of group oriented application services, the multicast communication in wire/wireless network has become a widely discussed researching topic. However solution for security, efnciency and scaleability of a multicast communications are not enough to be satisfactory. Tn this paper, we Propose a new secure, efficient and scalable multicasting protocols to provide a integrated multicast service. Our protocol is an authenticated key establishment protocol which has been designed specifically for use with low powered computationally weak equipment such as Cellular phone and PDA(Personal Digital Assistant).