PET검사 작업환경에 있어서 APRON의 방어에 대한 고찰

이성욱,김승현,지봉근,이동욱,김정수,김경목,장영도,방찬석,백종훈,이인수,Lee, Seong-wook,Kim, Seung-hyun,Ji, Bong-geun,Lee, Dong-wook,Kim, Jeong-soo,Kim, Gyeong-mok,Jang, Young-do,Bang, Chan-seok,Baek, Jong-hoon,Lee, In-soo 대한핵의학기술학회 2014 핵의학 기술 Vol.18 No.1

PET/CT기기의 발달로 인한 검사시간의 단축과 대중화로 인해 검사건수도 꾸준히 증가하고 있다. 이는 방사선 작업종사자의 피폭선량도 함께 증가시키는 결과를 초래한다. 본 연구는 PET/CT 검사에 있어서 에너지가 강한 $^{18}F-FDG$를 apron을 착용 시 방사선 차폐율을 측정하고 차폐효과를 알아보고자 하였다. 또한 $^{99m}TC$과의 차폐율을 비교하여 방사선 작업종사자의 피폭선량을 최소화하는 것에 목적을 두고 진행하였다. 실험방법은 2013년 5월 2일부터 5월 10일까지 8일간 PET/CT 검사를 위해 본원을 방문한 10명의 환자를 대상으로 하였고 PET/CT 주요 작업공간인 $^{18}F-FDG$ 분배실, 환자 안정실($^{18F}$주사 후 환자 대기장소), PET/CT 검사실 모두 3곳을 선정하여 Apron장착 전과 apron장착 후로 나누어 선량율 변화를 측정하였다. 정확한 측정을 위해서 환자 또는 Source부터의 거리는 1 m로 고정하였다. 또한 Apron의 선량감소율을 비교하고자 $^{99m}TC$의 source에도 같은 방법을 적용하여 측정하였다. 측정결과 $^{18F}FDG$ 분배실에서 L-BLOCK만 있는 경우 평균 $0.32{\mu}Sv$였고 L-block+apron의 경우 $0.23{\mu}Sv$이였으며 두 경우의 선량과 선량율의 차이는 각각 $0.09{\mu}Sv$, 26%로 나타났다. 안정실에서 apron이 없는 경우 평균 $33.1{\mu}Sv$였고 apron이 있는 경우 평균 $22.3{\mu}Sv$였다. 두 경우의 선량과 선량율의 차이는 각각 $10.8{\mu}Sv$, 33%로 나타났다. PET/CT실에서의 apron이 없는 경우 평균 $6.9{\mu}Sv$였고 apron이 있는 경우 평균 $5.5{\mu}Sv$였다. 두 경우의 선량과 선량율의 차이는 각각 $1.4{\mu}Sv$, 25%로 나타났다. $^{99m}TC$은 apron이 없는 경우 평균 $23.7{\mu}Sv$였고 apron이 있는 경우 평균 $5.5{\mu}Sv$였다. 두 경우의 선량과 선량율의 차이는 각각 $18.2{\mu}Sv$, 77%나타났다. 실험결과 환자에게 투여한 후의 $^{99m}TC$의 경우 평균 77%의 차폐율을 나타내었고 $^{18}F-FDG$의 경우 평균 27%의 비교적 낮은 차폐율을 보였다. source 자체만을 비교하였을 때에 $^{18}F-FDG$는 17%의 차폐율을 보였고 $^{99m}TC$은 77%의 차폐율을 보였다. $^{99m}TC$에 비해 낮은 차폐효과이지만 $^{18}F-FDG$ 역시 apron에 대한 차폐효과가 있음을 알 수 있었다. 그러므로 PET/CT 검사에 있어서 $^{18}F-FDG$과 같은 고에너지에 맞는 apron을 착용한다면 방사선 작업종사자의 피폭선량을 최소화 할 수 있을 것으로 사료된다. Purpose: The advancement in PET/CT test devices has decreased the test time and popularized the test, and PET/CT tests have continuously increased. However, this increases the exposure dose of radiation workers, too. This study aims to measure the radiation shielding rate of $^{18}F-FDG$ with a strong energy and the shielding effect when worker wore an apron during the PET/CT test. Also, this study compared the shielding rate with $^{99m}TC$ to minimize the exposure dose of radiation workers. Materials and Methods: This study targeted 10 patients who visited in this hospital for the PET/CT test for 8 days from May 2nd to 10th 2013, and the $^{18}F-FDG$ distribution room, patient relaxing room (stand by room after $^{18}F-FDG$ injection) and PET/CT test room were chosen as measuring spots. Then, the changes in the dose rate were measured before and after the application of the APRON. For an accurate measurement, the distance from patients or sources was fixed at 1M. Also, the same method applied to $^{99m}TC's$ Source in order to compare the reduction in the dose by the Apron. Results: 1) When there was only L-block in the $^{18}F-FDG$ distribution room, the average dose rate was $0.32{\mu}Sv$, and in the case of L-blockK+ apron, it was $0.23{\mu}Sv$. The differences in the dose and dose rate between the two cases were respectively, $0.09{\mu}Sv$ and 26%. 2) When there was no apron in the relaxing room, the average dose rate was $33.1{\mu}Sv$, and when there was an apron, it was $22.3{\mu}Sv$. The differences in the dose and dose rate between them were respectively, $10.8{\mu}Sv$ and 33%. 3) When there was no APRON in the PET/CT room, the average dose rate was $6.9{\mu}Sv$, and there was an APRON, it was $5.5{\mu}Sv$. The differences in the dose and dose rate between them were respectively, $1.4{\mu}Sv$ and 25%. 4) When there was no apron, the average dose rate of $^{99m}TC$ was $23.7{\mu}Sv$, and when there was an apron, it was $5.5{\mu}Sv$. The differences in the dose and dose rate between them were respectively, $18.2{\mu}Sv$ and 77%. Conclusion: According to the result of the experiment, $^{99m}TC$ injected into patients showed an average shielding rate of 77%, and $^{18F}FDG$ showed a relatively low shielding rate of 27%. When comparing the sources only, $^{18F}FDG$ showed a shielding rate of 17%, and $^{99m}TC$'s was 77%. Though it had a lower shielding effect than $^{99m}TC$, $^{18}F-FDG$ also had a shielding effect on the apron. Therefore, it is considered that wearing an apron appropriate for high energy like $^{18}F-FDG$ would minimize the exposure dose of radiation workers.

N-doped $TiO_2$/PAN 복합 나노섬유의 제조와 광촉매 특성

이성욱,이태상,리강,원방방,황택성,이승구,Lee, Sung-Wook,Lee, Tae-Sang,Li, Gang,Won, Bang-Bang,Hwang, Taek-Sung,Lee, Seung-Goo 한국섬유공학회 2009 한국섬유공학회지 Vol.46 No.6

The $TiO_2$/PAN based composite nanofibers having photocatalytic activity were prepared by sol-gel process, electrospinning and post-treatments. Electrospinning solution was prepared by mixture of $Ti(OBu)_4$, PAN, acetic acid and DMF with different ratio. As-spun nanofibers were treated with different way to prepare the anatase $TiO_2$/PAN nanofibers and the N-doped $TiO_2$/PAN nanofibers. In this study, the morphology and diameter of the electrospun and heat treated composite nanofiber were analyzed, and crystal structure of nanofiber after heat treatment and N-doping was analyzed. Furthermore, photocatalytic decomposition of the nanofiber, crystallized in various condition, against the malachite green aqueous solution, was evaluated.

항균성을 가진 Quinoxaline 4-Oxides의 합성과 Pyridazino[3,4-b]quinoxaline으로의 고리화반응

이성욱,허재혁,정희선,김호식,Lee, Seong-Uk,Hur, Jae-Hyuck,Jung, Hee-Sun,Kim, Ho-Sik,Kurasawa, Yoshihisa 대한화학회 2002 대한화학회지 Vol.46 No.6

카이제곱 통계량과 지지벡터기계를 이용한 스팸메일 필터

이성욱,Lee, Song-Wook 한국정보처리학회 2010 정보처리학회논문지B Vol.17 No.3

본 논문은 지지벡터기계를 이용하여 스팸메일을 자동으로 분류하는 시스템을 제안한다. 이메일에 포함된 단어의 어휘 정보와 품사 태그 정보를 지지벡터기계의 자질로 사용한다. 우리는 카이제곱 통계량을 이용하여 자질을 선택한 후 각각의 자질을 TF, TF-IDF, 이진 가중치 등으로 표현하여 실험하였다. 카이제곱 통계량을 이용하여 선택된 자질들을 이용하여 SVM을 학습한 후, SVM분류기는 각각의 이메일의 스팸 여부를 결정한다. 실험 결과, 선택되어진 자질들이 성능향상을 가져왔으며, TREC05-p1 스팸 말뭉치에 대해 약 98.9%의 정확도를 얻었다. We propose an automatic spam filter for e-mail data using Support Vector Machines(SVM). We use a lexical form of a word and its part of speech(POS) tags as features and select features by chi square statistics. We represent each feature by TF(text frequency), TF-IDF, and binary weight for experiments. After training SVM with the selected features, SVM classifies each e-mail as spam or not. In experiment, the selected features improve the performance of our system and we acquired overall 98.9% of accuracy with TREC05-p1 spam corpus.

Combustion and emission characteristics of HCNG in a constant volume chamber

이성욱,Han-Seung Lee,박영준,조용석 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.2

Finding an alternative fuel and reducing environmental pollution are the main goals for future internal combustion engines. Hydrogenmethane (HCNG) is now considered an alternative fuel due to its low emission and high burning rate. An experimental study was carried out to obtain fundamental data for the combustion and emission characteristics of pre-mixed hydrogen and methane in a constant volume chamber (CVC) with various fractions of hydrogen-methane blends. A pre-mixed chamber was used to obtain a good mixture of these gases. Exhaust emissions were measured using a Horiba exhaust gas analyzer for various fractions of hydrogen-methane blends. The results showed that the rapid combustion duration was shortened, and the rate of heat release elevated as the hydrogen fraction in the fuel blend was increased. Moreover, the maximum mean gas temperature and the maximum rate of pressure rise also increased. These phenomena were attributed to the burning velocity, which increased exponentially with the increased hydrogen fraction in the fuel blend. Exhaust HC and CO₂concentrations decreased, while NO_x emission increased with an increase in the hydrogen fraction in the fuel blend. Our results could facilitate the application of hydrogen and methane as a fuel in the current fossil hydrocarbon-based economy and the strict emission regulations in internal combustion engines.

'유전 비밀의 실체' 재조명되는 세포정보 RNA

이성욱,Lee, Seong-Uk 한국과학기술단체총연합회 2003 과학과 기술 Vol.36 No.3

한국인에 대한 누액 안정성 조사

이성욱,심현석,장성주,Lee, Seong-Wook,Sim, Hyun-Seog,Jang, Seong-Joo 한국안광학회 2001 한국안광학회지 Vol.6 No.2

건안은 콘택트렌즈를 착용하는 대부분의 환자에게서 쉽게 나타날 수 있으며 방치해 두면 누액의 안정성이 줄어들고 누액의 찌꺼기, 점액이 점점 증가하면서 각막 얼룩이 형성되어 눈에 충혈, 건조감 등을 동반할 수 있다. 본 연구에서는 51명의 성인 남녀를 대상으로 건성안을 판단하기 위해 Schirmer test, TBUT, 순목 횟수 등을 조사하였다. 건성안 검사 방법 중 순목 횟수는 1분에 평균 19회였고 Schirmer test의 평균은 5분에 25mm이였으며, TBUT는 평균 7.1초로 나타났다. 이런 결과로 TBUT 검사치가 낮으면 순목 횟수가 증가하는 것으로 나타났다. The purpose of our study was stability of tear film for Korean. In the 1970s, the major problem for the contact lens practitioner was the management of contact lens parameters. In the 1980s, oxygen permeability was the main problem in contact lens practice: now it is dry eyes. To appropriately fit the patient with contact lenses it is imperative to know in advance if the patient has a marginal dry eye. Based on the initial diagnosis appropriate care can be taken to minimize problems with the result that the patient can successfully wear contact lenses. A well known test for dry eyes is Schirmer test which has shown to be useful for diagnosing Sjogren syndrome. Biomicroscopy can often unmask numerous problems. The classical test for marginal dry eye is measuring the tear break up time(TBUT). A dry eye problem with contact lenses is often caused by the lid. If an incomplete blink is responsible for the dry eye it is possible to change the situation by blinking exercises. The result of these test, mean value of age was 22.8, mean value of blink rate was 19 times/min, mean value of Schirmer test was 25 mm/5 min, mean value of TBUT was 7.1 sec.

동아시아 해역 해수면 순열속의 장기 변동 특성

이성욱,나정열,Lee, Seong-Wook,Na, Jung-Yul 한국해양학회 2000 바다 Vol.5 No.2

동아시아 해역에서의 해양-대기 상호 작용의 장기 시 ${\cdot}$ 공간 변동 특성을 이해하기 위해 1978년부터 1995년까지 18년간 12시간 간격으로 연속적으로 산출된 해수면 순열속 자료를 이용하여 경험적 직교함수 분석을 하였다. 전체분산의 73%에 해당하는 3개 모드중, 1년 주기성이 우세한 제 1모드는 황해 산동반도 부근과 동해 중앙부 및 북동부 해역에서 변동이 크게 나타났다. 남쪽과 북쪽이 쌍극자형의 공간적 변동 양상을 보이는 제 2모드에서는 3.6년과 2.3년의 주기성이 우세하게 나타났다. 제 2모드 시간계수는 엘니뇨와 밀접한 관련이 있는 것으로 판단되며 태평양 동부 적도 해역의 해수면 수온 변동과는 반대 위상을 가지며 4개월의 시간 차이를 갖는 것으로 나타났다. 동쪽과 서쪽이 쌍극자형의 변동성을 갖는 제 3모드에서는 6-9년 주기의 성분이 다른 모드에 비해 뚜렷이 나타났다. 또한 산동반도 남부해역과 블라디보스톡 외해에서는 겨울철 열 손실이 800W/$m^{2}$가 넘는 강한 열손실이 발생하는 경우가 빈번하며 산동반도 남부 해역에서의 발생 빈도가 블라디보스톡 남부해역보다 약 2배 정도 많은 것으로 나타났다. 발생 시기는 블라디보스톡 외해에서는 1월에 주로 발생하는 반면 산동반도 남부에서는 12월과 1월에 걸쳐 나타나는 차이를 보였다. In order to extract the spatio-temporal characteristics of long-term variability of the net heat flux on the sea surface in the East Asian marginal seas, empirical orthogonal function (EOF) analysis was conducted using data set calculated every 12 hours interval during 1978-1995. Among the first three modes explaining 73% of the total variance, the first mode having high peak at 1 year period indicates high variability area around the Sandong Peninsula and central and northeastern part of the East Sea. In the second mode which has spatial distribution of dipole type at the north and south, the peaks appear at 3.6 year and 2.3 year cycles. Time coefficient of the second EOF is believed to have close relation with the E1 Nino and has out-of-phase variation with NINO3 SST. Lagged correlation between NINO3 SST and time coefficient of the second EOF indicates four month time delay in the NINO3 SST. In the third mode which has opposite sign at the east and west, the periodicity of 6-9 year cycle has relatively clear appearance compared to other two EOFs. Also, high heat loss exceeding 800 W/$m^{2}$ in winter time occured at the south part of the Sandong Peninsula and Vladivostok. It reveals more frequent occurrence of about two times at the Sandong Peninsula than Vladivostok. The event is concentrated in January at Vladivostok, but it occurs primarily in December and January at the Sandong Peninsula.

GPGPU를 이용한 영상 품질 측정 프로그램의 가속화 연구

이성욱,변기범,김기수,홍지만,Lee, Seonguk,Byeon, Gibeom,Kim, Kisu,Hong, Jiman 한국스마트미디어학회 2016 스마트미디어저널 Vol.5 No.4

최근 그래픽 처리 장치(GPU)의 발전과 개발자 친화적인 GPGPU(General-Purpose computing on Graphics Processing Units)기술의 발전으로 인해 그래픽 처리 장치를 활용한 병렬 컴퓨팅의 사용이 확대되고 있다. 이를 통해 과학, 의학, 공학 등 많은 분야에 걸쳐 기존 CPU 컴퓨팅 환경보다 더 빠른 처리속도로 결과 값을 얻어 낼 수 있게 되었다. 본 논문은 CPU 기반 컴퓨팅과 GPU 기반 컴퓨팅의 연산처리 속도의 차이의 비교를 위해 기존 CPU 기반으로 구현된 영상 품질 측정 프로그램을 NVIDIA사의 GPGPU기술을 사용할 수 있도록 프로그램을 포팅한다. 포팅한 프로그램을 바탕으로 GPGPU기술을 통한 프로그램의 가속화에 대하여 연구한다. 가속화된 프로그램은 CPU 기반의 프로그램보다 약 1.83배 정도의 실행 속도를 가진다. 또한 CPU 기반의 프로그램을 GPU 기반으로 수정할 때 생기는 제약과 문제점에 대해서도 기술한다. Recently, parallel computing using GPGPU(General-Purpose computing on Graphics Processing Units) according to the development of the graphics processing unit is expanding. This can be achieved through the processing speeds faster than traditional computing environments across many fields, including science, medicine, engineering, and analysis. However, in using the GPU technology to implement the a parallel program there are many constraints. In this paper, we port a CPU-based program(Video Quality Measurement Program) to use technology. The program ported to GPU-based show about 1.83 times the execution speed than CPU-based program. We study on the acceleration of the GPU-based program. Also we discuss the technical constraints and problems that occur when you modify the CPU to the GPU-based programs.

적분형 슬라이딩 서피스를 이용한 TDCSA(Time Delay Control With Switching Action)의 와인드업 방지를 위한 기법의 개발

이성욱,장평훈,Lee, Seong-Uk,Jang, Pyeong-Hun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.8

The TDCSA(Time Delay Control with Switching Action) method, which consists of Time Delay Control(TDC) and a switching action of sliding mode control(SMC), has been proposed as a promising technique in the robust control area, where the plant has unknown dynamics with parameter variations and substantial disturbances are preset. When TDCSA is applied to the plant with saturation nonlinearity, however, the so-called windup phenomena are observed to arise, causing excessive overshoot and instability. The integral element of TDCSA and the saturation element of a plant cause the windup phenomena. There are two integral effects in TDCSA. One is the integral effect occurred by time delay estimation of TDC. Other is the integral term of an integral sliding surface. In order to solve this problem, we have proposed an anti-windup scheme method for TDCSA. The stability of the overall system has been proved for a class of nonlinear system. Experiment results show that the proposed method overcomes the windup problem of the TDCSA.