레이저 가공 산란패턴의 유형에 따른 도광판의 휘도 및 균일도 향상에 관한 전산모사

박소희,이승석,마혜준,최은서,신용진,Park, So-Hee,Lee, Seung-Suk,Ma, Hye-Joon,Choi, Eun-Seo,Shin, Yong-Jin 한국광학회 2010 한국광학회지 Vol.21 No.6

레이저로 가공된 평면산란패턴을 가지는 도광판은 도광판 상부로 방출되는 광이 광원과 가까운 부분에 편중되는 문제로 인해서 전체적인 휘도 분포가 균일하지 않은 문제점을 가지고 있었다. 이를 해결하기 위해 도광판 후면에 레이저를 이용하여 도광판 내부에서 특징적인 기울기를 가지는 산란패턴을 만듬으로써 도광판 상부로 방출되는 광의 균일도를 향상시키고자 하였다. 본 논문에서는 도광판 후면의 산란패턴을 간격과 가공 깊이를 다르게 조절하여 설계하고 이에 따른 도광판의 성능의 차이점을 가공전에 분석하고자 전산모사를 수행하였다. 본 논문에서 제안한 산란패턴을 가지는 도광판은 기존의 도광판의 휘도와 균일도에 비해 높은 향상을 가질 것으로 예상되는 바이다. Laser-induced scatterer patterns in a light guide panel(LGP) have provided partially concentrated light distribution, especially near the light entrance of the LGP. Additional treatments for enhancing performance of the LGP, such as gradually increased processing depth, were also developed, but minor improvement was observed in the fabricated LGP. To solve this problem, we designed a revised scatterer pattern to be inscribed into the LGP using different laser processing depths and different separation distances between patterns. Performance feasibility of the proposed pattern was analyzed with simulation before laser inscription in the LGP. The LGP inscribed with the proposed scatterer patterns contributes improvements in luminance and uniformity of the LGP.

후두 결핵의 후두 내시경 소견과 임상 양상 분석

이상혁,이승석,이노희,반재호,이경철,진성민,Lee, Sang-Hyuk,Lee, Seung-Suk,Lee, No-Hee,Ban, Jae-Ho,Lee, Kyung-Chul,Jin, Sung-Min 대한후두음성언어의학회 2006 대한후두음성언어의학회지 Vol.17 No.1

Background and Objectives: There has been a gradual decline in the incidence of laryngeal tuberculosis due to effective an-tituberculous chemotherapy and improvement in the standard of living. During the last decade, however, the disease has changed its clinical pattern. We aimed to study a clinical and telescopic evaluation of laryngeal tuberculosis. Materials and Method: A retrospective clinical analysis was done for 16 patients who diagnosed laryngeal tuberculosis from January 2000 through December 2004. All patients had a complete clinical and laboratory work-up including telescopy, chest X-rays, sputum cultures, Tbc PCR(polymerase chain reaction). Laryngeal biopsies were performed in some cases. All the patients received proper antituberculous chemotherapy. Results: The patients age ranged from 21 to 59 with a mean age 43. The male to female ratio was 10:6. The prominent presenting symptom was hoarseness. The various telescopic findings were categorized: 7 patients showed ulcerative, 4 patients granulomatous, 3 patients ulcerofungative, 2 patients had nonspecific inflammatory lesions. Involving sites were true vocal cord most commonly in 12 patients. Three of 16 patients had normal chest X-ray fmding. Among 16 patients, 4 patients showed positive response for AFB stain, 13 patients showed positive for Tbc PCR. Biopsy was done for 3 patients who were not confirmed in initial tuberculous test. All patients responded satisfactorily to antituberculous medication. Conclusion: The telescopic findings and clinical manifestations of laryngeal tuberculosis have changed and seemed to be different from those of classic reports. Thus, the clinicians who deal with the various symptoms and diseases should be aware of the existence of laryngeal tuberculosis and the changing patterns of the disease.

적외선 열화상을 이용한 인장하중에 따른 원공시험편의 온도변화 해석

김경석(Kyoung-Suk Kim),김민근(Min-Kwen Kim),최만용(Man-Yong Choi),이승석(Seung-Seok Lee),강기수(Ki-Soo Kang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

The infrared thermography(IRT) is a technique measuring the radiated energy to objects through the detector. IRT is a non-contact, non-destructive, real-time measurement technique that enables to measure surface temperature fields. When operating the mechanical devices, It is necessary to study the mechanical deformations by temperature evolutions. In this paper, the relationship between tensile speed and temperature evolution is investigated. Experimental results show the radiation of thermal energy in elastic and plastic deformation depends on tensile speed. Thermal radiation energy in elastic deformation is neglected which is independent on tensile speed. and thermal radiation energy in plastic deformation is rapidly increased and the maximum of that appear at ultimate strength.

교사 직업군에서의 음성장애와 악화요인에 관한 연구

김태형,진성민,송윤경,이승석,이경철,권기환,Kim, Tae-Hyung,Jin, Sung-Min,Song, Yun-Kyung,Lee, Seung-Suk,Lee, Kyung-Chul,Kwon, Kee-Hwan 대한후두음성언어의학회 2004 대한후두음성언어의학회지 Vol.15 No.1

Background and Objective : Voice disorders are one of the major occupational hazards of school teaching. Prolonged voice use through verbal instruction has been implicated as a cause of vocal impairment among members of this profession. They all depend on their voice for their livelihood and are greatly alarmed by slightest alteration in voice quality. Despite considerable research in the area of voice problems in teachers, the prevalence of voice disorders in this group is unknown. Severe voice problems can affect teacher's ability to teach in the classroom. Materials and Method : This study investigated the prevalence of self-reported voice problems in teachers using a survey of a simple random sample of middle school teachers (n=1000). As part of the survey, teachers were asked to report voice problems for the day of the survey, duration, main symptom, smoking, caffeine, alcohol history etc. Results : The reponse rate was 91%(n=94) with 89.7%(n=812) teachers reporting voice problems on the day of the survey, and 40%(n=330) of these group reporting the history of medical consult. Conclusion : These finding indicate a need for vocal hygiene education in teachers and for the development of educational programs aimed at preventing voice problems in this group of professional voice users.

광섬유 FBG 센서를 이용한 탄성파 검출

서대철(Dae-Cheol Seo),권일범(Il-Bum Kwon),윤동진(Dong-Jin Yoon),이승석(Seung-Suk Lee),이정율(Jung-Ryul Lee) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.1

음향방출법은 압력용기 구조에서 존재하는 결함이나 누출을 탐지하거나 모니터링 하는데 유용한 도구로 부상하였다. 본 연구에서는 브레그 격자에 근거한 음향방출센서 시스템이 개발되었다. 다양한 길이의 센싱부를 포함하는 다양한 형태의 광섬유 브레그 격자센서가 제작되었고 PZT 펄서와 연필심 파괴를 이용하여 시험되었다. 두 가지 형태의 센서부착법이 사용되었다. 첫째는 광섬유 브레그 격자센서가 접착제를 이용하여 표면에 완전히 부착되는 방법이고 둘째는 센서의 한쪽 부분만 표면에 부분적으로 고정하고 다른 쪽은 외팔보와 같이 작동하도록 하는 방법이다. 이렇게 함으로써 센싱부의 길이에 비례하는 고유진동수를 갖는 광섬유 브레그 격자센서를 구성할 수 있다. 본 연구에 사용된 센서 시스템의 최종 목적은 원자력발전소 상부 관통관의 균열이나 누출을 탐지하는 온라인 모니터링 시스템에 사용하는 것이다. Acoustic emission(AE) has emerged as a powerful nondestructive tool to detect or monitor preexisting defects and leaks in the vessel structures. A Bragg grating based acoustic emission sensor system is developed. Various type of fiber Bragg grating sensor including the variable length of sensing part was fabricated and prototype sensor system was tested by using PZT pulser and pencil lead break sources. Two types of sensor attachment were used. First, the fiber Bragg grating sensor was attached fully to the surface using bonding agent. Second one is that one part of fiber was attached to the surface partly by bonding and the other part of fiber will be act as a cantilever. That is, the resonant frequency of the fiber Bragg grating sensor will depend on the length of sensing part. The final goal of the sensor system is to provide on-line monitoring of cracks or leaks in reactor vessel head penetration of nuclear power plants.

석회암 골재를 사용한 콘크리트에 대한 비파괴 강도 평가연구

오병환 ( Oh¸ Byung-hwan ),강의영 ( Jiang¸ Yi-rong ),인광진 ( In¸ Kwang-jin ),김지철 ( Kim¸ Ji-cheol ),이승석 ( Lee¸ Seung-suk ) 한국구조물진단유지관리공학회 2000 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.4 No.2

The non-destructive tests are widely used to predict the strength of existing structures. However, the current prediction equations give no satisfactory results when the aggregate, water to cement ratio, ages of concrete are different. The purpose of the present study is to propose the prediction equations for strength evaluation of concrete with limestone aggregate focusing on the rebound method and ultrasonic pulse velocity method. The major test variables include water to cement ratio and curing methods. The water to cement ratios are 0.3, 0.4, 0.5, 0.6, 0.7 respectively and the curing methods cover air-dry condition and standard curing condition. The present study indicates that the test data and the proposed equations agree well with each other.

Austenite Stainless 강의 Polythion 산에 의한 응력부식균열

김동훈,이승석 대한금속재료학회(대한금속학회) 1979 대한금속·재료학회지 Vol.17 No.2

304 austenite stainless 강의 입계균열을 polythion 산에 C-ring 형태의 시편을 침지시켜 검토하였으며, 용접부위에 대해서도 같은 방법으로 조사하였다. 응력제거 열처리, 냉각 속도, 부가 응력에 대한 제 현상을 조사해서 다음과 같은 결과를 얻었다. 304 austenite stainless 강의 polythion 산에 의한 응력부식균열은 입계균열이며 인장 응력 방향에 수직이다. 용접부위의 균열은 결정립이 성장된 열영향부에서 일어난다. 응력제거 열처리를 해 주었을 때 1050℃에서 수냉, 노냉시켰을 때 모두 효과가 좋으며 850℃에서는 노냉시켰을 때만이 효과가 좋다. polythion 산에서 응력 부식 균열을 방지해 주기 위해서는 모든 열처리에서 공냉시키는 것 보다 노냉시키는 것이 효과가 좋다. 부가응력이 큰 값을 가질수록 잠복기는 짧아지므로 부가응력 및 잔류응력이 작아지도록 설계하고 열처리를 해주어야만 한다. 부가응력과 파단에 이르는 시간을 대수로 취한 값을 도표화하면 knee가 나타나며 이 점의 부가응력은 42% MgCl₂를 부식매질로 실험했을 때와 거의 일치한다. Intergranular cracking properties of 304 austenitic stainless steel, particularly its welding region, have been evaluated by exposing C-ring specimen to polythionic acid. Effects of stress relief annealing temperature, cooling rate, and applied stress have been closely investigated. The results obtained are as follows. The stress corrosion cracking of 304 austenitic stainless steel is preferred at intergranular boundary and normal to the direction of tensile stress. The cracking of welding region happens in heat affected zone where grain is coarsened. When stress relief annealing is carried out, the efficiency is significant at 1050℃ furnace cooling or water quenching, at 850℃ furnace cooling. Preventing SCC in polythionic acid, furnace cooling is better than air cooling in all heat treatment. As the applied stress has higher value, the incubation period is shorter, so one must design and heattreat to lessen applied streess and residual stress. Plotting applied stress against log time-to-failure, knee of the plot appears. The stress of this point is similar to the stress which is shown by boiling 42% MgCl₂ Solution.

Monitoring and Optimizing Catalytic Reactor Performance Using Activity Index

Shin, Se Hee,Lee, Seung Suk,Park, Young Ho 중앙대학교 생산공학연구소 1997 생산공학연구소 논문집 Vol.6 No.1

촉매반응기의 조작은 화학공학에서 중요한 부분이다. 현재의 촉매의 상태를 나타내는 지표를 정량화할 수 있다면 비교적 숙련되지 않은 엔지니어라 할지라도 반응기의 성능을 점검할 수 있다. 본 연구는 적절히 정의된 촉매 활성계수를 이용하여 이러한 목적을 달성하는 방법을 제시하는 것이다. 이 활성계수는 속도상수의 pre-exponential factor를 표준화하여 정의된다. propene의 수소와, 석유의 탈황 및 납사유분의 촉매개질반응을 예로 들어 활성계수의 이용법을 설명하였다. 상업용 반응기는 단열조건하에서 조업되기 때문에 pilot plant에서 등온조건하에서 얻어진 속도식을 사용하여 활성계수를 결정하는 방법을 제시하였다. 납사의 촉매개질반응에서는 촉매의 산도를 적정선으로 유지하는 것이 효율 최적화의 중요 요소인데 3 가지 형태의 계수를 사용하여 산도를 예측하는 방법을 제시하였다. 제시된 방법들은 결국 상업용 반응기에서 그 유용성이 입증되어야 할 것이다. 새로운 형태의 납사공정 모델 REFKIM에 대한 개요를 설명하였다. 납사공정 반응모텔의 개발은 가치있는 앞으로의 연구과제로 사료된다. The performance of catalytic reactors is a major concern for chemical engineers. If a quantitative measure of current catalytic activity is identified, the catalytic reactor performance can be closely monitored by relatively inexperienced engineers. The purpose of the present paper is to propose a method of monitoring catalyst performance by means of a suitable activity index. The activity index is a concept essentially based on a normalized pre-exponential factor. Propene hydrogenation, hydrodesulfurization of petroleum, and catalytic reforming of naphtha have been discussed. For naphtha reforming, in which a proper control of catalyst acidity is crucial for reactor optimization, three types of activity indices are proposed to diagnose the acidity lever. The ultimate usefulness of the proposed activity indices needs to be tested in commercial units. A new reforming kinetic model REFKIM currently under development in the author's laboratory is briefly described. Development of a practical but reliable reforming kinetic model is believed to be a challenging future research area.

흰쥐 위점막 상피세포의 배양초 세포소기관 표지효소의 변화

성언기,이융창,이승석 대한해부학회 1996 Anatomy & Cell Biology Vol.29 No.2

Rifampin에 의한 급성 신부전 1례

김응석,이정호,이승석,이동철,이영현,서완다,양창헌 東國大學校 醫學硏究所 1995 東國醫學 Vol.3 No.-

Rifampin은 항결핵치료제로 매우 좋은 효과를 얻고 있으며, 특히 Rifampin을 포함한 병용요법으로 결핵단기요법을 가능케 하였다. 부작용은 오심 및 구토 등의 위장관장애, 혈청 transaminase치 및 bilirubin치 상승 등의 간기능 장애, 근무력감 및 감각이상 등의 신경장애와 과민반응으로 피부염과 인푸루엔자 유사증세가 나타나며 드물게는 혈소판 감소증, 용혈성 빈혈, 급성 신부전등이 생길 수 있다. 이 중 Rifampin에 의한 급성 신부전은 국내에서도 그 증례들이 보고되고 있으며 중독한 부작용을 보이므로 항결핵제 투여시 이러한 점에 대한 주의가 필요하다. 이에 저자들은 Rifampin복용 후 발생한 급성 신부전 1예를 경험하였기에 보고하는 바이다. Rifampin induces various adverse reactions including fever, nausea and vomiting, abdominal pain, jaundice, petechiae, thrombocytopenia, and acute renal failure etc. It has been well defined that adverse reactions to rifampin is more common when the drug is given intermittently and latter resume. We have experienced a case of acute renal failure after taking a single dose (600㎎) of rifampin. The case was 52 years old women who received irregular anti-tuberculosis therapy due to pulmonary tuberculosis during 12 months, 8 years ago. At this admission, she took a single dose (600㎎) of rifampin, and on the same day chest discomfort and chill were developed, so it was discontinued. And then abdominal pain, nausea, oliguria and elevated BUN & Creatinine followed. On 9th day after onset, hemodialysis was started. But patient was expired by complicated pneumonia on 51th day after onset. So we report a case with the relevant literature.