초음파 센서를 이용한 이동 로봇

배지훈,김종철,박경용,강민구,김갑일 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

In this paper, design and construction of mobile robot is conducted and the error reduction and obstacle avoidance techniques is introduced. Up to now, in the design of most mobile robots, there are emphasis on the compensation of tracking errors using the additional sensors and guidance method, rather than the reduction of the tracking errors of motor itself and wheel errors. In this purpose, high performance motor and encoder are used for the driving actuator, and the acceleration/deceleration technic is introduced to reduce the driving errors. Also ultrasonic sensor performs obstacle avoidance, which is proved using the driving test.

인산염계 실리카 매몰재의 성분변화에 따른 티타늄의 주조특성

김광만,은진원,이상배,김경남 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.2

A large increase in the use of titanium in density is driven by the desire to take advantage of titanium's excellent biocompatibility and its high resistance to corrosion. The development of investments suitable for titanium castings is critical because their mechanical properties are greatly affected by the surface-reacted layer. The purposes of this study were to evaluate the characteristics of Titanium Vest Ⅱ(CO) and experimentally produced four phosphate- bonded SiO₂ investments(EA, EB, EC, ED). A great deal of attention was focused on the influence of investments, such as setting time, compressive strength, casting compatibility, casting defects, surface microhardness and interfacial zone of the cast titanium. The following results were obtained; 1. The setting time of all experimental groups were significantly shorter than control group(p<0.05). 2. Experimental groups were significantly greater than control group in compressive strength of 1hr and 2wks(p<0.05) and there was no significant difference among the experimental groups(->0.05). Compressive strength after 2wks was significantly greater than 1hr in all tested groups(p<0.05). 3. EA was showed the highest casting compatibility and CO the lowest. 4. There was no fin in the casting of all groups. There were small porosities in a dental x-ray inspection of EA. 5. CO was showed the highest microhardness at the distance of 50 ㎛ from the surface. 6. The interfacial zone was composed of four layers in all groups. There was irregular and thick layer in CO. According to these results, titanium is castable with experimentally produced phosphate-bonded SiO₂investments. In addition, there is room for further investigation of investment materials to improve the precise casting of titanium.

프랙탈 시그네쳐를 이용한 질감영상 분별

金準哲,嚴景培,李俊煥 全北大學校 1994 論文集 Vol.37 No.-

Texture is one of the important features of images and it has been widely used for image analysis. The fractal signature model is used as a means of classifying textured images. The changes in measured area with the changing resolution is used for calculating the fractal signature of textures. The area decreases at coarser resolutions since fine details that contribute to the area disappear. Fractal properties are computed from the rate of this decrease in area, and are used for texture classification. In the experiment to classify images, the method shows good performance as much as 84-100* of correct classification ratio. The texture pictures in this paper are taken from Brodatz. We find the best performance can be achieved when the area distribution rather than fractal signature is used with the fuzzy Hausdorff distance metric.

Privacy 문제를 위한 안전한 RFID 인증 프로토콜에 대한 연구

배경만,김종훈 동아대학교 공과대학부설 정보통신연구소 2007 情報技術硏究所論文誌 Vol.15 No.1

유비 쿼터스 환경에서 사람이나 객체의 자동식별을 위한 기술인 RFID (Radio Frequency IDentification)는 차세대 유비쿼터스 사회 의 핵심 기술이며 가장 가시적인 성과를 낼 수 있는 기술이다. 하지만 transponders는 보안성을 가지고 있지 않기 때문에 RFID 시스템은 보안이 취약하다. RFID 시스템을 다양한 분야에 적용하기 위한 가장 큰 이슈는 security와 privacy 문제 이다. 이러한 RFID 보안 이슈는 꼭 해결해야 할 문제이다. 본 논문에서는 RIFD 시스템의 security와 privacy 문제를 해결하기 위한 안전한 인증 프로토콜을 제안하였다. 제안한 인증 프로토콜은 기존 기법에서 고려되지 않은 리더와 서버사이의 인증을 제안하였다 제안한 인증 프로토콜은 Hash와 XOR 연산이 가능해야 하며 물리 적인 공격에 대해서는 고려가 안 된 제한 사항이 있다. 향후 다양한 보안 위협에 대한 지속적인 연구가 필요하다고 생각된다. There is RFID for auto identification of people and object in Ubiquitous surroundings. RlFD is not only the core technology of Ubiquitous society but also represent the technology of visible result. RFID is getting better now. For example miniaturiation, going down of price and high technical skill. RFID makes a matter possible to confront various utility division and use purpose from a big capacity and high speed transmission to a subminiature, low price. But ever though RFID system is really convenient, RFID is bad for private information and we will check for attack materiality security about weakness of RFID. And we search how to defend. We study and evaluate a few protocols from each of those streams, identify possible vulnerabilities, and provide altemate solutions when possible. We provide security analysis of the proposed solutions.

릴레이 궤환을 이용한 PID제어기 상수의 자동 조정에 관한 연구

金恩培,南炫道,李坰鎭 단국대학교 1990 論文集 Vol.24 No.-

In this paper, Auto-tuning methods for parameter tuning of the PID controller is proposed. The existing methods of parameter tuning rules is compared with the proposed method, and the simple robust estimation technique is introduced. The tuning procedure is as follows : The relay feedback loop are added to the system to obtain the critical gain and critical period. Then appropriate test signal is generated automatically using the relay control, the controller parameter is calculated by using the Ziegler-Nichols parameter setting rule. Also the sensitivity on error and noise are reduced by using the hysteresis characteristic of relay, and the controller for the time-varying system is presented using the resetting of the PID parameters in case that the sum of errors is greater than the dead zone.

납착 분위기에 따른 교정용 선재의 레이저 납착효과

김경남,김광만,이상배 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.2

The electric welding and/or soldering with flame torch to make a hook or spring on orthodontc wires seemed to have insufficient strength, anti-corrosion, anti-discoloration, and set down resistance. In this study, tension-franture load and micro-hardness of laser welded joint for stainless stee(SS), Cr-Co(CC), TMA(TM) and Ni-Ti(NT) wires were tested with universal testing machine and micre-hardness tester. The welding wer done under air and argon(Ar)-gas atmospheres. The enegy intersity of Nd:YAG laser was changed and two diffenrent welding methods, butt and lap joints, were tested. The results were showed that tension-fracture loads of butt joint welded SS, CC and TM were increased with higher laser enegy intensity in Ar-gas atmosphere compared to air atmosphere except 2J. In NT, 2, 4, and 10J were showed higher tension-fracture loads under Ar-gas atmosphere(p<0.05). In TM, tension-fracture load was increased with higher laser energy intensity under Ar-gas but decreased under air atmosphere. Tension-fracture loads of the lap joint welding were showed not significantly differences between air and Ar-gas atmospheres except 2J of SS and 2 and 6J of CC(p<0.05). In TM, higher laser energy intesity groups were showed higher tension-fracture load under Ar-gas atmosphere. They were showed significant diffenrence except in 4J group(p<0.05). NT also were showed higher result in Ar-gas atmosphere. They were showed joint failure in 8, 10, and 12J group under air atmosphere. The tesion-fracture load fo 12J group of SS, CC and TM were showed the highest result. The micre-hardness of CC joint showed significantly lower result in atmosphere. SS and NT showed no significant differences. TM showed higher hardness atmosphere. This study showed that SS, CC, and TM wires were seemed to be able to get sufficient laser welded joint under clinical condition.

열공형과 비열공형 피질하 혈관성 치매에서 위험인자의 차이에 관한 비교 연구

배희준,정지향,유경호,나덕렬,김상윤,최경규,양동원,손의주,이상도,김재우,박경원,김응규,이재홍,박미영,한일우,함동석,최문성,하충건,최성혜,이애영,이병철,한설희 대한치매학회 2003 Dementia and Neurocognitive Disorders Vol.2 No.2

Backgrounds and Objectives: Vascular dementia is a group of dementing disoders arising from various stroke syndrome. Among these. subcortical ischemic vascular dementia (SIVD) is regarded as a relatively distinct clinical entity. However, MRI patterns of SIVD are not homogenous. In some patients, lacunes are dominant, and in others, subcortical white matter changes are. This study was designed to compare risk factor profiles between SIVD with and without multiple lacunes. Methods: We divided 47 subjects (22 males, mean age. 68 years) recruited from VADAPET (Multicenter Trial For Evaluation Of The Changes In the PET Images Of Subcortical Vascular Dementia Patient) study into two groups one with more than 5 lacunes in deep gray matter (lacune group) and the other with 5 or less(non-lacune group) Clinical characteristics and laboratory findings of two groups were compared. Results: Nineteen of 47 patients (40%) belonged to the lacune group. The lacune and non-lacune groups d d not differ in the following variables: age, hypertension, diabetes mellitus, hyperlipidemia heart disease, history of stroke or TIA, history of trauma or major surgery, family history of hypertension stroke, or dementia, age at diagnosis of dementia, body mass index, white blood cell count, ESR, CRP, fibrinogen, hemoglobin A1C, total cholesterol. LDL cholesterol creatinine, proteinuria, glucosuria, and microhematuria. However, male sex, smoking alcohol. hemoglobin, and HDL cholesterol were possibly associated more with lacune group SIVD than with non-lacune group (p<0 1) Multivariate analyses revealed that smoking, hemoglobin, and HDL cholesterol were independent predictors of SIVD with multiple lacunes Conclusion: Our study suggests that SIVD with multiple lacunes may be significantly different in smoking habits hemoglobin, and HDL cholesterol from SIVD without multiple lacunes.

역할 계층을 위한 암호학적인 키 할당 방법

배경만,김종훈 東亞大學校附設 情報技術硏究所 2005 情報技術硏究所論文誌 Vol.13 No.1

The problem of access control in a security hierarchy must be considered mandatoryly for access control about structural document. Many schemes based on cryptography have been proposed to solve this problem. However, previous schemes need a large amount of storage for storing the secret key is required in their scheme. In this paper, We propose efficient key management method of the height to solve problem on the access control in user role hierarchy.

반건식-백필터에 의한 소각배가스 중의 HCI, SOx 제거 (Ⅰ)

배병훈,신남철,고경숙,김춘희,문종익,임경택 동아대학교 환경문제연구소 1997 硏究報告 Vol.20 No.1

This study has been carried out to investigate the removal efficiencies of HCl/SOx in a Spray-Dryer/Fabric-Filter system. In HCl/SOx removal, we could identify the key factors such as spray dryer outlet temperature, molar equivalence ratio(MER) and fabric filter velocity, but we couldn't find out the correlation of HCl and SOx. The removals of HCl/SOx were inversely proportional to spray dryer outlet temperature(l30~170℃) and filter velocity(l.0~1.5 m/min), at the MER, HCl removal efficiency was strongly proportional to MER, but SOx, removal efficiency was not particularly increased by MER over 1.5. The removal efficiencies of HCl/SOx were improved over 10% at the fabric filter. In this Spray-Dryer/Fabric-Filter system, HCl/SOx removal efficiencies were about 99%, 96% respectively.

산후에 발병한 특발성 부갑상선 기능저하증 I 예

김정인,김상용,신병철,김경남,서영욱,이범주,김진화,배학연 朝鮮大學校 附設 醫學硏究所 2002 The Medical Journal of Chosun University Vol.27 No.2

Hypoparathyroidism is usually the result of an inadvertent surgical removal of all the parathyroid glands, In some instances, not all the tissues are removed, but the remainder undergoes vascular supply compromise secondary to the fibrotic changes in the neck after surgery, Previously, the surgery for hyperthyroidism was the most frequent cause of acquired hypoparathyroidism. Idiopathic hypoparathyroidism is a relatively rare disease that is characterized by hypocalcemia and hyperphosphatemia due to a parathyroid hormone deficiency of an unknown cause, It usually develops at a young age, and shows various clinical symptoms and signs accompanied with hypocalcemia. In addition, it is rarely associated with polyglandular autoimmune syndrome during the follow-up. Hypocalcemia and idiopathic hypoparathyroidism associated with labor and lactation are rarely reported condition previously. We here describe a case of a woman in whom the symptomatic severe hypocalcemia appeared after her delivery. We reviewed all the previously reported cases and suggest a possible physiological explanation for the association between pregnancy, lactation, and the appearance of symptomatic hypocalcemia.