비강우시 도시 합류식 하수도의 오염부하 산정을 위한 최적관측시간 산정연구

최용훈,원철희,박운지,서지연,신민환,이찬기,최중대,Choi, Yong-Hun,Won, Chul-Hee,Park, Woon-Ji,Seo, Ji-Yeon,Shin, Min-Hwan,Lee, Chan-Ki,Choi, Joong-Dae 한국농공학회 2009 한국농공학회논문집 Vol.51 No.3

Flow and pollution load were monitored at 2 combined sewer outlets (C-1 and C-2) of urban watersheds during dry weather from September, 2004 to April, 2006 for 20 months. The objectives were to investigate the diurnal variation of flow and pollutant load and to find the proper sampling time that could measure representative flow and pollutant load. Pollution load closed to the average daily load at C-1 could be measured at 00:00 hour and by the mean of 15:00 and 18:00 hour measures, and 15:00 and 21:00 hour measures, respectively. In addition at C-2, it was 21:00 hour and the mean of 15:00 and 18:00 hour measures. This study concluded that arbitrary sampling of flow and water quality could cause large errors in the estimation of urban pollution load and recommended that urban combined sewers should be monitored when flow and water quality showed daily average and concentration.

대뇌 신경 교종 ¹⁸F-FDG PET/CT 검사에서 포도당 부하 기법에 대한 고찰

최용훈,박민수,임한상,김재삼,Yong-Hoon Choi,Min-Soo Park,Han-Sang Lim,Jae-Sam Kim 대한핵의학기술학회 2023 핵의학 기술 Vol.27 No.1

Purpose The purpose of this study is to determine whether the glucose loading method (GLM) is useful in the differentiation of cerebral gliomas by comparing it with fasting images. Materials and Methods The patients were 70 people diagnosed with cerebral gliomas, and the equipment was Discovery 710 (GE Healthcare, MI, USA). All patients fasted for more than 6 hours, and fasting images and GLM were performed under the same imaging conditions, and the examination interval was 1 to 14 days. GLM administered 250 ㎖ of 10% glucose solution prior to radiopharmaceutical injection. SUVmax of cerebral glioma and SUVmean of cerebral cortex were measured and then compared and analyzed by tumor-to-normal brain cortex ratio (TNR). Statistical analysis confirmed the difference between the two images with an independent-sample t-test. Results The averages of GLM and fasting TNR were 1.26 and 1.09, respectively, which were 15.6% higher in GLM. In low-grade, the difference in TNR was insignificant at 4%, but in high-grade, 23%, GLM was high. There was a statistically significant difference between the two images (P=0.008), but there was no statistically significant difference in TNR in the low grade (P=0.473), and there was a very significant difference in the high grade (P=0.005). Conclusion GLM increased TNR for cerebral gliomas. In particular, it was found that the TNR increased more in the high grade. Therefore, GLM is considered to be useful for the differentiation of high-grade gliomas.

노지 작물의 적정 관개계획을 위한 토양수분의 공간변이성 분석

최용훈,김민영,김영진,전종길,서명철,Choi, Yonghun,Kim, Minyoung,Kim, Youngjin,Jeon, Jonggil,Seo, Myungchul 한국농공학회 2016 한국농공학회논문집 Vol.58 No.5

Due to droughts and water shortages causing severe damage to crops and other vegetations, much attention has been given to efficient irrigation for upland farming. However, little information has been known to measure soil moisture levels in a field scale and apply their spatial variability for proper irrigation scheduling. This study aimed to characterize the spatial variability and temporal stability of soil water contents at depths of 10 cm, 20 cm and 30 cm on flat (loamy soil) and hill-slope fields (silt-loamy soil). Field monitoring of soil moisture contents was used for variogram analysis using GS+ software. Kriging produced from the structural parameters of variogram was applied for the means of spatial prediction. The overall results showed that the surface soil moisture presented a strong spatial dependence at the sampling time and space in the field scale. The coefficient variation (CV) of soil moisture was within 7.0~31.3 % in a flat field and 8.3~39.4 % in a hill-slope field, which was noticeable in the dry season rather than the rainy season. The drought assessment analysis showed that only one day (Dec. 21st) was determined as dry (20.4 % and 24.5 % for flat and hill-slope fields, respectively). In contrary to a hill-slope field where the full irrigation was necessary, the centralized irrigation scheme was appeared to be more effective for a flat field based on the spatial variability of soil moisture contents. The findings of this study clearly showed that the geostatistical analysis of soil moisture contents greatly contributes to proper irrigation scheduling for water-efficient irrigation with maximal crop productivity and environmental benefits.

PET/CT 검사에서 Q.Clear 기법의 유용성에 대한 고찰

최용훈,김정열,최영숙,임한상,김재삼,Choi, Yong Hoon,Kim, Jung Yul,Choi, Young Sook,Lim, Han Sang,Kim, Jae Sam 대한핵의학기술학회 2017 핵의학 기술 Vol.21 No.2

최근 PET/CT 장비의 성능의 발전과 다양한 기법의 개발로 민감도와 해상도등 영상 품질을 개선할 수 있게 되었다. 본 논문에서는 GE사의 Discovery IQ 장비의 Q.Clear (a fully convergent iterative reconstruction) 기법을 이용하여 영상의 질 향상에 유용성이 있는지 알아보고자 한다. 장비는 Discovery IQ (GE Healthcare, MI, USA)를 사용하였다. NEMA IEC Body Phantom의 배후방사능과 열소 체적(10 mm, 13 mm, 17 mm, 22 mm)의 비를 1:4로 하고 3분간 촬영하여 VPHDs (VUE Point High-Definition SharpIR)와 Q.Clear의 대조도를 비교 분석하였다. PET/SPECT Performance Phantom에 $^{18}F-FDG$를 187 MBq을 주입 후 4분간 촬영하여 해상도와 균일도를 비교 분석하였다. 그리고 100명의 임상 환자에서 질환의 종류와 상관없이 2 cm 미만의 작은 병소의 SUVmax를 측정하여 t-test 통계분석하였다. NEMA IEC Body Phantom에서 VPHDs와 Q.Clear의 대조도가 $63.6{\pm}5.7%$, $75{\pm}4.8%$로 나왔고 PET/SPECT Performance Phantom에서 해상도는 VPHDs가 9.2 mm, Q.Clear가 7.3 mm로 나왔다. 균일도는 Q.Clear가 10.8% 더 우수하였다. 임상 환자의 t-test 통계 결과 p-value가 0.021로 유의한 차이가 있었다. 임상환자에서 SUVmax는 Q.Clear에서 높게 측정 되었으며, 신호대 잡음 비도 우수하였다. 이는 부분체적효과의 영향을 줄였기 때문으로 볼 수 있다. Phantom test와 임상 환자의 결과 모두 Q.Clear를 적용 하였을 때 영상품질이 향상된 것을 확인하였다. 이러한 영상 품질 향상은 병소를 더욱 정확하게 발견할 수 있고 나아가 선량저감과 환자평가 그리고 영상 분석 등 다양한 방면에서 활용할 수 있을 것으로 사료된다. Purpose Recently, the performance of PET/CT scanner has been improved and various techniques have been developed to increase the image quality such as Sensitivity and Resolution. The purpose of this study is to evaluate the usefulness of Q.Clear (a fully convergent iterative reconstruction) technique of GE Discovery IQ equipment to enhance the image quality. Materials and Methods All scans were acquired by Discovery IQ (GE Healthcare, MI, USA). In NEMA IEC Body Phantom test, Background to Hot-sphere (10 mm, 13 mm, 17 mm, 22 mm) ratio was 1:4 and scan time was 3 minutes. The images were reconstructed by VPHDs (VUE Point High-Definition + SharpIR) and Q.Clear to evaluate each Contrast. We injected 18F-FDG 187 M㏃ to PET/SPECT Performance Phantom. And then it was scanned for 4 minutes to evaluate Resolution and Uniformity. T-test statistical analysis was performed on SUVmax of small lesions less than 2 cm in 100 clinical patients regardless of disease type. Results In the NEMA IEC Body Phantom, the Contrast was $63.6{\pm}5.7%$ (VPHDs) and $75{\pm}4.8%$ (Q.Clear). In the PET/SPECT Performance Phantom, the Resolution was 9.2 mm (VPHDs) and 7.3 mm (Q.Clear). Uniformity of Q.Clear was 10.8% better than VPHDs. T-test statistic of the clinical patients showed a significant difference of p value of 0.021. Conclusion Both the phantom test and the clinical results showed that the quality of the image was improved in Q.Clear was applied. The SUVmax was highly measured in Q.Clear and the lesions were clearly distinguished visually. Therefore Q.Clear can be useful in various aspects such as dose-reduction, patients evaluation and image analysis.

¹⁸F-Florbetaben PET/CT 검사에서 영상분석에 대한 고찰

최용훈,반영각,임한상,김재삼,Choi, Yong-Hoon,Bahn, Young-Kag,Lim, Han-Sang,Kim, Jae-Sam 대한핵의학기술학회 2022 핵의학 기술 Vol.26 No.1

¹⁸F-FBB 판독은 회백질과 백질의 신호강도를 육안으로 비교하여 이루어진다. 정량화된 영상분석을 판독과 비교하여 영상분석의 유용성을 평가하고자 한다. 환자는 판독결과를 기준으로 음성과 양성을 100명씩 나누었고 FBB 300 MBq 주입하고 90분 뒤 20분간 촬영했다. 장비는 Discovery 600 (GE Healthcare, MI, USA)을 사용하였다. 제조사에서 제공하는 아밀로이드 판독 기준을 근거하여 4개의 관심영역을 설정하였다. 영상분석은 각 SUVmean을 소뇌로 나누어 SUVr를 산출하고 전체 영역에서의 평균 SUVr로 진행하였다. 통계분석은 ROC Curve를 통한 Cutoff 도출과 독립표본 t-test의 그룹간 차이, 그리고 Kappa test를 통한 판독결과와 일치도를 분석하였다. 전체 영역에서의 평균 SUVr의 Cutoff는 1.23으로 나왔다. Cutoff를 사용한 판독결과와 일치도는 음성에서 95/100 (95 %), 양성에서 92/100 (92 %)로 나왔다. t-test 결과 그룹 간에 통계적으로 유의한 차이가 있었고(P < 0.05) Kappa 통계 결과 0.867로 높은 일치도를 나타냈다(P < 0.05). 영상분석의 결과가 통계적으로 유의하며 판독결과에도 높은 일치도를 보여 주었다. 추가적으로 FBB 영상분석은 아밀로이드가 축적된 부위를 3D 매핑하여 볼 수 있고 위치추정이 가능하며 정량분석 결과를 세분화하여 볼 수 있다. 정량화된 FBB 영상분석을 보조지표로 활용한다면 판독에 도움이 될 것으로 사료된다.

¹⁸F-Sodium fluoride PET 이용한 심장 석회화 정량평가에 대한 고찰

최용훈,이승재,강천구,임한상,김재삼,Choi, Yong Hoon,Lee, Seung Jae,Kang, Chun Goo,Lim, Han Sang,Kim, Jae Sam 대한핵의학기술학회 2019 핵의학 기술 Vol.23 No.2

관상동맥 석회화 검사에 컴퓨터단층촬영(Comtuted tomography, CT)을 사용하지만 고위험군인 미세석회화 감별에는 어려움이 있다. $^{18}F$-sodium fluoride ($^{18}F-NaF$)가 미세석회화를 진단하는데 매우 유용하다는 연구가 해외에서 보고되고 있다. 본 논문에서는 $^{18}F-NaF$ PET 영상으로 석회화를 정량평가 하고 그 유용성을 알아보고자 한다. 환자는 총 45명($67.1{\pm}6.9$세)으로 $^{18}F-NaF$을 250 MBq 주입하고 1시간 뒤 30분간 영상을 획득하였다. 장비는 Discovery 710 (GE Healthcare, MI, USA)을 사용하였으며 모든 환자는 PET 검사 전 혈관조영CT (CTAngiography, CTA)를 촬영 하였다. 석회화의 SUVmax를 측정하고 좌심방의 배후방사능을 측정하여 Target to Background (TBR) 구한 뒤 정량 분석하였다. ROC 곡선(Receiver Operating Characteristic Curve)을 통하여 고위험군을 분류하였다. 융합영상에서 관상동맥 석회화는 226개로 나왔으며 SUVmax는 $1.15{\pm}0.39$으로 나왔다. 28명(62%)에서 58개가 고위험군으로(TBR>1.25)분류 되었다. 나머지 168개는 $TBR{\leq}1.25$로 나왔다. $^{18}F-NaF$ PET 영상으로 미세석회화의 정량평가가 가능하였고 고위험군을 분류할 수 있었다. 혈관조영CT와 $^{18}F-NaF$ PET을 병행한다면 위험도가 높은 미세석회화를 조기 진단하는 새로운 영상 진단법이 될 수 있을 것으로 사료된다. Purpose Although computed tomography (CT) is used for coronary artery calcification, it is difficult to differentiate between high risk microcalcifications. Studies have shown that $^{18}F$-sodium fluoride ($^{18}F-NaF$) is very useful for the diagnosis of microcalcifications. In this study, we aimed to evaluate the usefulness of $^{18}F-NaF$ PET imaging in quantitative evaluation of calcification. Materials and Methods A total of 45 patients ($67.1{\pm}6.9years\;old$) were injected with 250 MBq of $^{18}F-NaF$ for 1 hour and images were acquired for 30 minutes. All patients underwent CT angiography (CTAngiography, CTA) before the PET scan. The SUVmax of calcification was measured and the background radioactivity of the left atrium was measured to determine Target to Background (TBR) and quantitatively analyzed. High risk group was classified through ROC curve (Receiver Operating Characteristic Curve). Results There were 226 coronary artery calcifications in the cohort and SUVmax was $1.15{\pm}0.39$. Of the 28 patients (62%), 58 were classified as high risk (TBR > 1.25). The remaining 168 were $TBR{\leq}1.25$. Conclusion $^{18}F-NaF$ PET images were available for quantitative assessment of microcalcifications and could be classified into high-risk groups. The combination of angiographic CT and $^{18}F-NaF$ PET may be a new method for early diagnosis of high-risk microcalcifications.

ICT 활용과 자기 주도적 학습력 신장을 위한 사회과 교수-학습 시스템 개발

최용훈,황선영,고병오,Choi, Yong-Hun,Hwang, Sun-Young,Goh, Byung-Oh 한국정보교육학회 2003 정보교육학회논문지 Vol.7 No.2

Individual studying that compose knowledge and improve efficiency of studying through collection of information by various class strategy which takes advantage of web, and Cooperative learning that can elevate sense of responsibility and solve the problem through communication with another person have been developed actively. But, individuation tutoring materials that is developed present doesn't fit of causing learner's interest, and stimulating curiosity about problem because mostly studying is gone in presentation form. Also, cooperative learning materials are lacking connection with actual course of education, application is difficult in real class spot. So, this research has applied self-directed learning, centered with interested operation activity, aimed at improvement in various thought. Also, we have developed social studies tuition-learning system, purpose to the management is possible with on-line project studying which could improve mind-decision ability and ICT application ability. This system is developed for flexible management could be possible in various class circumstance, and level learning could be done through accomplishment-test and the result could be applied by feedback process.

연구발표초록 ( 에너지 / 환경 ) : 철광석 예비환원용 환원성 가스제조 공정연구

최용훈,박대규,이일옥 ( Y . H . Choi,D . G . Park,I . O . Lee ) 한국화학공학회 1992 춘계학술발표회 Vol.- No.-

PET/CT 검사에서 종양의 특성에 따른 체적 측정 방법 비교

최용훈,반영각,오신현,임한상,김재삼,Choi, Yong Hoon,Ban, Yung Gak,Oh, Shin Hyun,Lim, Han Sang,Kim, Jae Sam 대한핵의학기술학회 2016 핵의학 기술 Vol.20 No.1

최근 다양한 학회에서 PET 정보로부터 기인하는 SUVmax, MTV, TLG 등으로 환자의 생존율을 분석하는 후향적 연구가 활발히 진행 중이다. 그러나 종양의 체적을 정확하게 측정하기 어렵고 명확한 방법이 없으며 술자 간 차이가 발생 할 수 있다. 따라서 본 연구에서는 종양의 특성에 따른 체적 측정 방법을 비교 평가하였다. NEMA IEC Body Phantom에 18F-saline을 채우고 구형($0.5cm^3$ 에서 $26.5cm^3$)과 불균형($20cm^3$ 에서 $200cm^3$)의 체적을 phantom 안에 삽입하여 Biograph truepoint 40 (Siemens medical system, Germany)로 촬영하였다. 체적과 배후방사능과의 ratio를 3.0, 5.0, 8.0, 18, 40으로 나누어 촬영하였다. 임상환자는 소화기계 암의 병기 설정 환자로 2010년도부터 2014년도 까지 무작위로 120명을 선택하였고 측정방법은 40% threshold, 50% threshold 그리고 MIMsoftware의 gradient segmentation기법인 PET EDGE를 사용하였으며 5년 이상 2명의 방사선사와 1명의 전공의가 3번 반복 측정 하였다. 관찰자간일치도를 분석하였고 조영증강 CT 체적과 측정 체적과의 일치 상관관계 계수를 분석하였다. Phantom test의 결과는 40% threshold 방법이 가장 우수하였다(r = 0.992, 0.997). 임상 환자 결과에서는 관찰자간일치도는 PET EDGE가 0.999 (CI: 0.998-0.999)로 높았고 측정 방법간의 통계적인 유의한 차이는 보이지 않았다(P = 0.620). CT체적과 PET 체적 간의 상관관계에선 40% 방법이 가장 우수하였다(r = 0.953). 그리고 종양과 배후방사능의 비가 증가할수록 측정 방법 간의 영향이 감소하였다. 임상 환자에서의 종양의 체적 측정 방법은 50% threshold방법이 가장 유용하고 종양의 특성에 대한 영향이 가장 적었다. 종양과 배후방사능의 비가 높을수록 측정 방법 간의 영향이 감소하기 때문에 PET/CT 검사에서 환자의 배후방사능을 줄이는 연구와 노력이 필요하다고 생각된다. Purpose Recent retrospective studies are being actively conducted to analyze the survival of patients with SUVmax, MTV, TLG, such as information from a variety of PET originating. However, there is no clear way is difficult to accurately measure the volume of the tumor may be the difference between the caster is raised. In this study, to evaluate compare the volume measuring methods according to the characteristics of the tumor. Materials and Methods 18F-saline to fill the NEMA IEC Body Phantom insert the volume of balance and imbalance in phantom were acquired to the Biograph truepoint 40 (Siemens medical system, Germany) PET/CT scanner. The ratio of the volume and Background was acquired as 3.0, 5.0, 8.0, 18, 40. Clinical patients were randomly selected 120 people in staging patients with cancer of the digestive system from the year 2010 until the year 2014. Measurement methods were used a 40% threshold, 50% threshold and gradient segmentation technique, i.e. PET EDGE. Five years of experience of the two radio-technologist and one doctor was measured by repeated three times. Analysis methods were Intraclass correlation coefficient and Pearson correlation. Results In Phantoms, the 40% threshold method gave the best concordance between measured and actual volumes (r = 0.992, 0.997). In clinical patient outcome agreement between observers EDGE it is as high as 0.999 (CI: 0.998-0.999). And there were no statistical significance of the difference between the measurements (P = 0.620). 40% threshold method showed the best correlation between the measurements (r = 0.953). Increasing the ratio of tumor to background decreased the influence of a measuring method. Conclusion How to measure volume of the tumor in the patient was clinically most useful is 50% and the lowest impact on the characteristics of the tumor. Therefore, to reduce the background of the patients in PET/CT scan, it should be required research and effort.

감자와 무를 재배하는 사질양토 고랭지 밭의 시비량에 따른 비점오염 발생량 비교

최용훈,원철희,박운지,신민환,신재영,이수인,양희정,최중대,Choi, Yong Hun,Won, Chul Hee,Park, Woon Ji,Shin, Min Hwan,Shin, Jae Young,Lee, Su In,Yang, Hee Jeong,Choi, Joong Dae 한국관개배수위원회 2012 한국관개배수논문집 Vol.19 No.1

This study was performed to monitor the runoff of sandy soils on alpine uplands between March 2008 and December 2009, and assess non-point source pollution load. The fields were used to cultivete poteto in 2008 and radish in 2009. The fertilizers used in 200S, compared to those used in 2009, contained 2.1 times of nitrogen, 1.9 times of phosphorous, and 2.3 times of potassium. In 2008, the annual pollution load indiceted SS 2,908.47kg/ha/yr, COD 67.95kg/ha/yr, BOD 50.72kg/ha/yr, TN l3.29kg/ha/yr, and TP 9.97kg/ha/yr. In 2009, the annual pollution load indiceted SS 3,908.34kg/ha/yr, COD 225.04kg/ha/yr, BOD 156.96kg/ha/yr, TN 18.88kg/ha/yr, and TP 36.41kg/ha/yr. The amount of fertilizers used was about twice greeter in 2008, but the amounts of TN in pollution load per unit of rainfall were similar by 0.031kg/ha/mm to 0.029kg/ha/mm, whereas the amounts of COD (0.16kg/ha/mm to 0.35kg/ha/mm), BOD (0.12kg/ha/mm to 0.24kg/ha/mm), and TP (0.023kg/ha/mm to 0.057kg/ha/mm) doubled in 2009. We can infer thet the surface covering by the growth of crop mainly affected the transport of T-N through the subsurface flow to reduce non-point source pollution.