• 대한기계학회논문집B
• /
• 제28권3호
• /
• pp.349-358
• /
• 2004

A low pressure impactor is an impaction device to separate airborne particles into aerodynamic size classes at low pressure condition. We designed a two-stage low-pressure impactor to classify submicron sized environmental aerosols. Performance evaluation was carried out for stages 1 and 2 by using an electrical method. Monodisperse liquid dioctyl sebacate (DOS) particles were generated using evaporation-condensation process followed by electrostatic classification using a DMA (differential mobility analyzer). The test particles were in the range of 0.08∼0.8$\mu\textrm{m}$. For the evaluation of the impactor we used two electrometers; one was connected to the impaction plate of the impactor and the other was to the Faraday cage used as a backup filter. The effect of polydispersity of test aerosols on the performance was investigated. The results showed that the experimental 50-% cutoff diameters at each impactor's operation pressure were 0.53 and 0.187$\mu\textrm{m}$ for stages 1 and stage 2, respectively. The effects of operation pressure on the cutoff diameter and the steepness of collection efficiency curves were also investigated.

• 대한기계학회논문집B
• /
• 제28권3호
• /
• pp.315-323
• /
• 2004

An electrical cascade impactor is a multi-stage impaction device to separate airborne particles into aerodynamic size classes using particle charging and electrical detection techniques. A Faraday cage and an aerosol charger, which are basic components of the electrical cascade impactor, were designed and evaluated in this study. The low-level current response of the Faraday cage was investigated with changing particle size and air flow rate by using sodium chloride (NaCl) particles. The response of the prototype Faraday cage was very similar to that of a commercial aerosol electrometer (TSI model 3068) within ${\pm}$5% for singly-charged particles. The response linearity of the prototype Faraday cage could be extended up to flow rate of 30 L/min. For the performance evaluation of the aerosol charger the monodisperse liquid dioctyl sebacate (DOS) particles, with diameters of 0.1∼0.8$\mu\textrm{m}$, were generated using spraying from an atomizer followed by evaporation-condensation process. Typical performance parameters of the aerosol charger such as P$.$n, wall loss, and elementary charges per particle were evaluated. The performance of the prototype aerosol charger was found to be close to that of the aerosol charger used in an electrical low pressure impactor (ELPI, Dekati).

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2002년도 학술대회 논문집
• /
• pp.135-137
• /
• 2002

In the favor of adjusting microwave signal, Hairpin type Filter, which delay microwave signal enough to several nanosecond, is a key component. One of the main advantage in using Hairpin type Filter is a conveniency for equipping with Delay Module, and because of having a wide bandwidth, Hairpin type Filter can be designed to satisfy the most applications. In this work, we attempted to estimate the delay time in a superconductive hairpin type filter A software to synthesize even and odd order equiripple hairpin type filter has been developed. This software arbitrarily locate its transfer zeros making symmetric of asymmetric amplitude response and equalizing group delay. Borland C++ compiler has been used. The program was designed to run under MS-DOS, Window 98, Window 2000. The program optimizes the position of the transfer function zeros in order to fulfill the group delay specification masks. We designed and fabricated a hairpin type HTS 2-pole microstrip bandpass filter to operate at 5.8Ghz. The fabrication method was pulsed laser deposition and YBCO films were deposited on sapphire substrates with a Ce$O_{2}$ thin layer as a buffer layer. We also developed a new style hairpin type filter by using interdigitide inner-pole. Compared to the same size regular hairpin type filters, our filters had a lower center frequency.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2002년도 춘계학술대회 및 임시총회
• /
• pp.252-255
• /
• 2002

최근 네트워크 취약점 검색 방법을 이용한 침입 공격이 늘어나는 추세이며 이런 공격에 대하여 적절하게 실시간 탐지 및 대응 처리하는 침입탐지시스템 구현은 어렵다. 본 논문에서는 시스템에 허락을 얻지 않는 서비스 거부 공격(Denial of Service Attack) 기술 중 TCP의 신뢰성 및 연결 지향적 전송서비스로 종단간의 통신서비스를 지원하는 3 way handshake를 이용한 SYN flooding 공격에 대하여 침입시도패킷 정보를 수집, 분석 및 침입시도여부를 결정하는 네트워크 기반의 실시간 침입시도탐지(Real Time Scan Detector) 메커니즘을 제안한다.

• 한국지능시스템학회논문지
• /
• 제18권5호
• /
• pp.649-658
• /
• 2008

본 논문에서는 기존의 PSO(Conventional Particle Swarm Optimization : CPSO) 알고리즘에서 매 반복횟수마다 매개변수 값을 적응적으로 변화시키는 적응 PSO(APSO) 알고리즘을 제안하였다. 본 논문에서 제안한 APSO의 성능을 평가하기 위해 De Jong함수, Ackley 함수, Davis 함수 Griewank 함수 등의 최소화 문제에 적용하여 실수형 유전알고리즘과 그 결과를 비교하여, 제안한 알고리즘에 대한 우수성을 증명하였다. 그리고 자계계측기와 설문지를 통해 얻은 전자계 노출량에 대한 실측데이터를 이용하여 개인생활 자계노출식 개발에 제안한 APSO를 적용하여 그 우수성을 입증하였다.

• 대한치과교정학회지
• /
• 제44권5호
• /
• pp.268-277
• /
• 2014

A Brazilian girl aged 14 years and 9 months presented with a chief complaint of protrusive teeth. She had a convex facial profile, extreme overjet, deep bite, lack of passive lip seal, acute nasolabial angle, and retrognathic mandible. Intraorally, she showed maxillary diastemas, slight mandibular incisor crowding, a small maxillary arch, 13-mm overjet, and 4-mm overbite. After the diagnosis of severe Angle Class II division 1 malocclusion, a mandibular protraction appliance was placed to correct the Class II relationships and multiloop edgewise archwires were used for finishing. Follow-up examinations revealed an improved facial profile, normal overjet and overbite, and good intercuspation. The patient was satisfied with her occlusion, smile, and facial appearance. The excellent results suggest that orthodontic camouflage by using a mandibular protraction appliance in combination with the multiloop edgewise archwire technique is an effective option for correcting Class II malocclusions in patients who refuse orthognathic surgery.

• 한국전자통신학회논문지
• /
• 제8권12호
• /
• pp.1849-1856
• /
• 2013

서비스 거부공격, 즉 DDoS(Destribute Denial of Service) 공격은 정상적인 사용자가 서비스를 이용하지 못하도록 방해하는 공격 기법이다. DDoS 공격에 대응하기 위해서는 공격주체, 공격대상, 그리고 그 사이의 네트워크를 대상으로 다양한 기법들이 연구개발 되고 있으나 모두 완벽한 답이 되지 못하고 있는 실정이다. 본 연구에서는 DDoS 공격이 발생하는 근원지에서 공격의 사전 준비작업 혹은 공격에 이용되는 봇이나 악성코드 등이 발생시키는 네트워크 트래픽의 분석을 통해 발견된 악성코드 및 봇을 제거하거나 공격 트래픽을 중도에서 차단함으로써 DDoS 공격에 대해 효율적으로 대응하는 방법을 개발하는 것을 목적으로 한다.

• 소음진동
• /
• 제4권1호
• /
• pp.33-42
• /
• 1994

When a vibration is generated due to the misalignment, the reduction of the vibration level is not attainable unless a correct shaft alignment is conducted. In a turbine system, an alignment procedure requires quite a lot amount of expense and time. To reduce this effort, an algorithm of the turbine alignment is developed to be used in the computer program. The program consists of five parts : input, calculation, display of the results, file management, and printer output. In the input part, users must provide the data on the turbine number, the reference value of the alignment, and the number of the feet of the generator. In calculation, the moving distance of the bearing and the necessary amount of the shims are calculated. In the display and the output parts, the calculated results are displayed and calculated. In the display and the output parts, the calculated results are displayed and printed. Then, by using the file management, results and procedures conducted are saved in the floppy diskette or in the hard disk. The developed program can be run in IBM PC compatible with more than 640 KB of main memory with the operating system of MS-DOS v 3.3 or higher. It is developed for novice users with no experience or specialty in this field. The program is not only useful in the power plant application, but also helpful for recording of the alignment procedures.

• 정보학연구
• /
• 제7권4호
• /
• pp.9-20
• /
• 2004

본 연구에서는 일차적으로 현재 네트워크에서 심각한 문제 우해바이러스를 해결하기 우해서 VirusWall을 실험해본 결과 Dos를 막을 정도 밖에 안되고 이 문제를 해결하기 위해서 이차적으로 ESM, CIS와 MIS면으로 지능화된 인터넷과 Multiple Protocol 등 상황에 맞는 대처를 하도록 로그 분석시스템을 구현하였다. 결과적으로 ESM의 다양한 해킹과 바이러스에 대응하기 위한 지능적인 전사적 보안관리 시스템과 CIS를 이용하기 때문에 정보보호 측면에 폭넓게 이용할 수 있게 되었고, Site Design, Packet 전송별로 클릭할 수 있고, 내부 인터넷(GroupWare)까지 사용되었으며, Smart View를 통해서 전체적인 웹과 보안의 관계도 모니터링 할 수 있게 되었다.

• Toxicological Research
• /
• 제17권
• /
• pp.217-218
• /
• 2001

In a series of our screening for immunomodulating substances, we isolated prodigiosin from the culture broth qf Serratia marcescens B-1231. This compound inhibited the T cell-mediated immune responses such as concanavalin A-induced proliferation, mixed lymphocyte response, local graft versus host reaction and T-dependent antibody response at nontoxic concentrations. However. prodigiosin did not effect B cell-mediated immune functions such as lipopolysaccharide-induced proliferation and -activated polyclonal antibody production at the same concentrations. Prodigiosin did not cause death in vitro to lymphocytes at effective concentrations (＜100 nM) and also did not show toxicity in vivo to lymphoid organs at effective dos-ages (10 and 30 mg/kg). The pharmacological potencies were comparable to the activities of well-known T-cell specific immunosuppressants such as cyclosporin A. In our continuing study, mechanism of action of PDG is investigated with respect to the effect of PDG on IL-2/IL-2R pathway and transcription factor.