A Study on Sheet Resistance and Temperature Stability of $RuO_2$-based Thick Film Resistors with Varying Glass Composition

최동욱,김준철,김근영,안철,Choi, Dong-Wook,Kim, Jun-Chul,Kim, Geun-Young,An, Chul The Institute of Electronics and Information Engin 1992 전자공학회논문지-A Vol.29 No.11

The dependence of electrical characteristics of RuO$_2$-based thick film resistors on the RuO$_2$ contents, glass composition variation and the firing temperatures was measured. The sheet resistance of resistors decreased as the contents of RuO$_2$ increased and at firing temperatures higher than C, the sheet resistance increased as the firing temperature increased. In case of using lead borosilicate glass-containing $Bi_{2}O_{3}$, the sheet resistance decreased as the contents of $Bi_{2}O_{3}$ increased. TCR changes from negative to positive values as RuO$_2$ contents increased and from positive to negative values as the firing temperature increased. TCR increased to positive values as $Bi_{2}O_{3}$ increased in the glass.

대절토부 사면의 패널식 옹벽보강에 따른 안정성 검토

최동욱,박준오,김대현,Dong-wook Choi,Jun-o Park,Daehyeon Kim 한국지반신소재학회 2024 한국지반신소재학회 논문집 Vol.23 No.2

대절토사면 안정성 확보를 위한 보강공법에 대한 다양한 신기술, 신공법이 적용되고 있지만 현장 지반정수 고려에 대한 설계적 한계가 존재하여 실제 시공 시 설계와 현장 지반 조건이 상이한 결과가 발생하고 있다. 본 연구대상지역인 여수시 일원에 있는 옹벽의 경우 5단계 옹벽 시공예정중이나, 현재 2단계 시공완료 시점에서 옹벽 상부의 균열, 옹벽전면의 침하 및 우수 유출등이 확인되었다. 1, 2단계 옹벽 시공 완료후, 발생된 옹벽 상부의 균열 및 침하와 옹벽 전면의 우수 유출에 대한 문제점을 발견하고 기존 안정성 검토의 결과를 재검토하고자 하였다. 기존 설계단계에서 붕적층에 대한 명확한 검토가 이루어지지 않아 지하수 유출로 인한 문제임을 확인하였으며, 이에 지하수위 조건을 보수적으로 반영하고자 옹벽 최상부에 지하수위선을 위치시켜 사면에 대한 안정성검토를 수행하였다. 검토결과, 우기시 안전율은 1.31로 기준안전율 1.3을 상회하는 결과를 확인하였으나, 지진시 안전율이 1.12로 기준안전율 1.3을 만족하지 못하는 것으로 확인되었다. 이에 기존 1, 2단 시공된 옹벽은 그라우팅을 이용한 마이크로 파일과 같은 보강공법을 적용하고, 붕적층에 대한 명확한 검토 수행수 추가 공사가 이루어져야할 것으로 사료된다. Various innovative technologies and methods are being applied to ensure the stability of steep rock slopes. However, there are design limitations concerning site ground conditions, leading to discrepancies between the designed and actual ground conditions during construction. In the case of the retaining wall in Yeosu, where the study area is located, although the construction of a 5-stage retaining wall is planned, at the current completion of the second stage, cracks on the upper part of the wall, settlement in the front of the wall, and seepage have been observed. After the completion of stages one and two, issues regarding cracks and settlement on the upper part of the wall and seepage in the front of the wall were discovered. Thus, there was a need to reevaluate the results of the existing stability assessment. It was confirmed that the issue was due to groundwater leakage, attributed to the lack of clear assessment of the colluvial soil layer during the initial design stage. Therefore, to conservatively reflect groundwater level conditions, a groundwater level contour was positioned at the top of the wall to conduct a slope stability assessment. The assessment results indicated that the safety factor during the rainy season exceeded the required value of 1.3, with a calculated safety factor of 1.31. However, during seismic events, the safety factor was determined to be 1.12, falling short of the required safety factor of 1.3. Therefore, it is suggested that the existing retaining walls constructed during stages one and two undergo reinforcement using methods such as micro-piles with grouting, and additional work should be carried out to ensure a clear assessment of the colluvial soil layer.

차세대 이동통신 시스템에서 유동적 USIM 카드를 이용한 인증 시스템

최동욱,황재영,정연호,Choi, Dong-Wook,Hwang, Jae-Young,Chung, Yeon-Ho 한국정보통신학회 2011 한국정보통신학회논문지 Vol.15 No.11

본 논문은 유동적 USIM(Universal Subscriber Identity Module)을 이용한 사용자 편의를 위한 인증시스템을 제안한다. 유동적 USIM 카드는 이동통신망 이용자에게 시스템에서 단말의 할당된 고유번호나 주민등록번호와 같은 개인화 정보를 인증의 인자로 이용하여 제한된 횟수나 사용시간을 허가하는 인증 방법이다. 본 연구에서 제안하는 모듈을 검증하기 위해 시뮬레이션을 수행하였으며 제안한 알고리즘 및 시스템이 현재의 시스템에서 완벽하게 동작하며, 기존의 USIM 카드를 사용하는 인증방법과도 높은 호환성을 확인하였다. 또한 유동적 USIM 카드를 이용하여 또 다른 인증방식을 설계할 수도 있음을 제시하였다. 제안하는 유동적 USIM 기술을 적용할 경우 간단하면서도 강력한 인증방법과 시스템을 개발할 수 있을 것이며 사용자 환경과 독립적으로 이동통신망 접근을 가능하게 해 줄 수 있다. This paper presents a user-friendly authentication system using a flexible USIM. In the proposed method and its system, the flexible USIM utilizes personalized data such as Mobile Directory Number(MDN) and social security number as the key to user authentication. The authentication method proposed in this paper permits limited times of use and/or limited duration of use. A simple simulation model shows that the proposed algorithm works well and shows high compatibility with existing authentication methods. In addition, an alternative or more advanced authentication system can be developed with the proposed flexible USIM card. It is seen that this simple alternative method will eventually be able to make wireless communication networks more easily accessible for subscribers, irrespective of user environments.

단안, 양안 정상안압녹내장에서 Primary Vascular Dysregulation 비교

최동욱,서울,기창원,Dong Wook Choi,Wool Suh,Chang Won Kee 대한안과학회 2010 대한안과학회지 Vol.51 No.5

Purpose: To compare the clinical symptoms and signs of primary vascular dysregulation (PVD) for unilateral and bilateral eye involvement in normal tension glaucoma (NTG). Methods: The authors administered a questionnaire to assess PVD in patients with NTG. The answers to the 10-item questionnaire (cold hands, migraine, sleep latency, thirst, hypotension, orthostatic hypotension, emotional stress, drug sensitivity, vertigo, and systemic vasospasm) were compared between patients with unilateral involved NTG and bilateral involved NTG (N=61). The groups were classified again according to age (criteria: 55 years), sex, and mean deviation via standard automated perimetry (criteria: -6 dB). Results: The answers to the questionnaire between patients with unilateral involved NTG and bilateral involved NTG were not different at the level of statistical significance. In groups classified according to age, sex, and mean deviation, none of the answers to the questionnaire were different at the level of statistical significance between the groups. Conclusions: Clinical symptoms and signs of PVD were not different between patients with unilateral or bilateral eye involvement in NTG. Systemic vascular factors may not be considered different between unilateral and bilateral eye involvement in NTG. J Korean Ophthalmol Soc 2010;51(5):721-727

경공막 유리체 절제술을 시행받은 무수정체안에서 이차적 전방인공수정체 삽입술의 임상고찰

최동욱,김언정,정인영,박종문,송준경,Dong Wook Choi,Eon Jeong Kim,In Young Chung,Jong Moon Park,Jun Kyung Song 대한안과학회 2005 대한안과학회지 Vol.46 No.1

Purpose: We studied the result and clinical significance of anterior chamber lens implantation in completely vitrectomized eyes without capsular support. Methods: We evaluated 15 aphakic eyes of 15 patients. According to the cause of pars plana vitrectomy, there were 6 eyes for lens dislocation, 5 for intraocular foreign body, and 4 for rhegmatogenous retinal detachment. Results: The final available postoperative best-corrected visual acuity was 0.5 or better in 9 eyes (60%). No statistically significant difference was noted in preoperative and postoperative IOP. The average of postoperative astigmatism was 1.14±0.79D. The most common early complication was temporary increase in IOP, but we could control IOP within normal limit with transient treatment. The postoperative late complications were glaucoma, IOL decentration and cystoid macular edema, but serious postoperative complications such as bullous keratopathy and retinal detachment were not found. Conclusions: The anterior chamber IOL implantation appears to be well tolerated and represents a simple alternative to transscleral fixation of a posterior chamber IOL in completely vitrectomized aphakic eyes.

신생아중환자의 phenobarbital 용량과 치료약물농도모니터링

최동욱(Dong Wook Choi,)예경남(Kyong Nam Ye),김정태(Jung Tae Kim),안숙희(Sook Hee An) 대한약학회 2018 약학회지 Vol.62 No.1

Phenobarbital is an anticonvulsant used for the treatment of neonatal seizure. Large inter-individual differences in the pharmacokinetics of phenobarbital required therapeutic drug monitoring (TDM). This study aimed to investigate the TDM practices of phenobarbital in the neonatal intensive care unit (NICU) and suggest the appropriate dosing and monitoring guidelines of phenobarbital for critically ill neonates. A single-center, retrospective chart review included NICU patients with a TDM consult of phenobarbital by a pharmacist and at least 1 serum concentration obtained. A total 79 drug concentration values for 28 patients were included in the analysis. The percentage of phenobarbital concentrations within the therapeutic range (15-40 mg/L) was 65.8%. Sub-therapeutic levels (〈 15 mg/L) were observed in 25 instances (31.6%). The percentage of concentrations within therapeutic range was significantly lower in preterm infants (52.9%) than in term infants (75.6%, p=0.024). Oral administration resulted in a significantly higher percentage of sub-therapeutic concentrations than intravenous administration (57.7% versus 18.9%, p=0.002). Patients with oral and intravenous administration received maintenance doses 3.5±1.1 and 3.9±1.1 mg/kg/day, respectively (p=0.114). The percentage of cases requiring dosage adjustment by a pharmacist was 41.8%. The rate of acceptance of pharmacist`s recommendations by physicians was 87.3%. For effective and safe treatment of phenobarbital in NICU patients, close monitoring is essential for preterm infants and the development of optimal dosing guideline for oral administration is required.

확장형 머플러 내부의 천공판 형상 최적화

최동욱(Dong Wook Choi),이진우(Jin Woo Lee) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.10

RFID 및 CC/PP를 활용한 맞춤화된 모바일 서비스 제공을 위한 시스템

최동욱(Choi Dong Wook),김용희(Kim Yong Hee),윤희용(Youn Hee Yong) 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.6

압력 강하를 고려한 머플러 천공판 최적설계

최동욱(Choi, Dong Wook),이진우(Lee, Jin Woo) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.4

An acoustical shape optimization problem is formulated for optimal design of a perforated reactive muffler with offset inlet/outlet. The mean transmission loss value in a target frequency range is maximized for an allowed pressure drop value between an inlet and an outlet. Partitions in the chamber are divided into several sub-partitions, whose lengths are selected as design variables. Each sub-partition has the same number of holes, whose sizes are equal. A finite element model is employed for acoustical and flow analyses. A gradient-based optimization algorithm is used to obtain an optimal muffler. The acoustical and fluidic characteristics of the optimal muffler are compared with those of a reference muffler. Validation experiment is carried out to support the effectiveness of our suggested method.

대수가능성비 기반의 효율적 인터리버 분할 다중접속기술의 성능 예측

최동욱(Dong-wook, Choi),정연호(Yeon-ho, Chung) 제어로봇시스템학회 2009 제어로봇시스템학회 합동학술대회 논문집 Vol.2009 No.12

본 논문은 4세대 이동통신에서 고려되고 있는 효율적인 인터리버 분할 다중접속 기술의 성능 예측 메커니즘을 제안한다. IDMA의 성능을 예측하기 위해 대수가능성비에 기반을 두어 단순히 대수가능성비(LLR) 값을 수신기의 단순 반복적 판단 프로세스에 넘겨서 인지할 수 있을 만큼의 성능을 낼 수 있게 반복 연산을 한다. 본 논문에서 제안하는 IDMA 시스템은 대수가능성비(LLR)를 이용해 시스템의 비트오율(BER) 성능을 예측하고, 시스템이 요구하는 성능을 얻기 위한 수신기의 반복 연산을 획기적으로 감소시킨다. 제안된 시스템의 성능에 대한 평가를 보면 기존의 방식과 유사한 비트오율(BER) 성능을 보여준다. 대수가능성비의 적용은 4세대 이동무선통신시스템의 유력한 표준으로 고려되고 있는 효율적인 IDMA 시스템 설계에 유용하게 적용할 수 있을 것이다.