광산 폐석의 알칼리 반응성에 대한 광물.암석학적 연구

임한욱,최성범,백환조,김덕현 강원대학교 석재복합신소재제품연구센터 1997 석재연 논문집 Vol.2 No.-

석회암을 이용한 골재의 알칼리 반응성을 측정하기 위하여 한국공업규격의 표준시험 방법에 의한 팽창성을 측정하였다. 기존의 연구결과에 의하면 특히 백운석을 포함하는 석회암의 경우 골재-알칼리 반응이 상당한 것으로 알려지고 있으나, 본 연구에 사용된 석회암 시료의 경우는 알칼리 반응성이 매우 작은 것으로 나타났다. 또한, 역학적 특성의 결과도 매우 양호하며 골재로서의 활용성이 충분한 것으로 판단된다. An experimental program was undertaken to investigate the alkali-aggregate reaction of limestone aggregates, following the standard testing method for potential alkali reactivity of carbonate rocks for concrete aggregates. It is generally known tat dolomitic limestones may exhibit high potential of alkali-aggregate reaction. However, the limestone samples employed in this study showed negligible effect of the alkali reaction, even with substantial dolomite content. It is also concluded that the mechanical properties of the limestone aggregates are adaptable for concrete aggregates

석골재자원 개발을 위한 균열제어 발파모델 연구

임한옥,김재동,김종훈,백승규 강원대학교 석재복합신소재제품연구센터 1998 석재연 논문집 Vol.3 No.-

본 연구에서는 석골재 자원개발에서 널리 사용되고 있는 발파 조건을 고려하여 암반의 변형 및 파괴거동에 대한 특성을 규명하기 위한 컴퓨터 모델링을 시도하였다. 현재까지 이루어진 몇몇 연구들은, 발파에 의한 암반의 거동을 실제 동하중이 적용되고 있는 상태와는 달리 정적 상태 하의 조건에서 주로 이루어져 왔다. 그러나 실제 발파 거동은 동적 거동을보이므로 동역학적 해석을 하지 않을 경우 많은 오차를 포함한 상태하의 개괄적인 특성의 추정에 그칠 수밖에 없는 단점을 지니고 있었다. 본 연구에서는 동하중 하에서의 탄소성 해석을 실시하여 채석시 발파 하중에 대한 암반의 하중 반응, 탄성 및 소성 변형의 발생 특성, 그리고 이로 인한 발파 균열의 성장 전파 특성을 규명함으로써 발파로 인한 균열의 능동적 제어와 보다 효율적인 발파가 이루어 질 수 있는 조건들을 규명하고자 하였다. 해석 결과 일반 발파공의 경우에서 탄성 모델의 경우 공반경의 약 3배인 6cm까지 집중된 응력의 크기가 파괴강도를 초과하는 것으로 나타났으며, 탄소성 모델의 경우 균열의 전파 거리는 공반경의 15배인 30cm까지 균열이 확장되었다. 또한 폭 5mm 길이 20mm의 노치가 가공된 발파공의 경우 공반경의 25배인 50cm까지 균열이 진전되었으며, 균열의 방향은 노치 첨단의 방향으로 생성되는 것을 알 수 있다. 노치의 폭과 길이에 의한 영향은, 폭은 10mm이하일 경우가 적합하다고 판단되며, 길이는 균열의 성장 길이에 비례하는 경향이 있는 것을 알 수 있었다. Conditions for developing an effective controlled blast model were studied using finite element method, analyzing elastic and elasto-plastic case under static and dynamic load for normal blast hole and notched blast hole. Results show that from the elastic analysis of normal blast hole with 2 cm radius, stress concentrated by blasting exceeds tensile strength for the region up to 6 cm from hole wall and in case of elasto-plastic analysis, it was expanded up to 30 cm. For the notched blast hole with its width of 5mm and length 20mm, crack due to blasting was propagated up to 50 cm.

Long-term Intraocular Pressure Elevation after Primary Angle Closure Treated with Early Phacoemulsification

Sung Uk Baek,Kwang Hyun Kim,Joo Yeon Lee,Kyung Wha Lee 대한안과학회 2018 Korean Journal of Ophthalmology Vol.32 No.2

Purpose: To assess long-term changes in intraocular pressure (IOP) and the development of glaucoma after early phacoemulsification in acute primary angle closure. Methods: Retrospective chart review of acute primary angle closure patients treated with phacoemulsification in attack eyes versus fellow eyes. Within a month after the angle closure attack, all subjects underwent cataract surgery and were divided into two groups: group A received cataract surgery on their attack eyes. Group B also received cataract surgery on their fellow eye after phacoemulsification of the attack eyes. Study outcomes were the prevalence of IOP rise (occurrence of IOP >21 mmHg) and the incidence of newly developed glaucoma. Results: Eighty-nine eyes were included, with 62 attack eyes in group A and 27 fellow eyes in group B. Group A (14 eyes, 22.58%) had a higher cumulative rate of IOP rise than group B (3 eyes, 11.11%) at 12 months (p = 0.001). Newly developed glaucoma was not observed in group B; however, 6 patients in group A developed glaucoma during the 12-month follow-up period (p < 0.001). Conclusions: The attack eyes treated with phacoemulsification showed a significantly higher prevalence of IOP rise and newly developed glaucoma than fellow eyes that received phacoemulsification. These findings suggest that there is a possibility of IOP rise and development of glaucoma even when angle closure and successful IOP control have apparently been achieved after phacoemulsification.

Motor Asymmetry and Interocular Retinal Thickness in Parkinson's Disease

Baek Sung Uk,강석윤,권순일,Park In Won,Suh Wool 대한의학회 2021 Journal of Korean medical science Vol.36 No.6

Background: To analyze the relationship between interocular difference of retinal thickness and motor asymmetry in Parkinson's disease (PD). Methods: Prospective case-control series analyzed 62 eyes of 31 patients with PD and 62 eyes of 31 age- and sex-matched control. Ophthalmologic examinations including optical coherence tomography (OCT) scans were performed in both groups, and in the patients with PD, motor function was evaluated on the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) to determine the clinically more affected side. Peripapillary retinal nerve fiber layer thickness (pRNFLT) and macular retinal thickness (mRT) were measured in both eyes, after which the interocular asymmetry of the OCT parameters was determined. Additionally, the more and less affected sides of the UPDRS-III were evaluated using Symmetric index. Results: The average and quadrant pRNFLT and mRT values between the two groups were not different, but the interocular asymmetry of the average mRT and asymmetry index of retinal thickness (AIRT) of temporal mRT were significantly higher in the PD patients than in the controls (P = 0.026 and 0.044). The sum of UPDRS-III showed a discrepancy between the more and less affected sides (P = 0.002); the calculated Symmetric index was 0.21 ± 0.19, which suggested asymmetric motor symptoms. The Symmetric index of UPDRS-III showed significant relations for interocular asymmetry of superior mRT and AIRT of average mRT (P = 0.001 and 0.008). Conclusion: In the PD patients, the interocular asymmetry of mRT was larger than in the controls, and the motor symptoms were asymmetric. Additionally, the interocular asymmetry of mRT showed a significant correlation with motor-symptom laterality.

Mental health symptoms among dependent contractors in Korea: a cross-sectional study based on the Fifth Korean Working Condition Survey

Seong-Uk Baek,Sung-Shil Lim,Sehyun Yun,Won-Tae Lee,Min-Seok Kim,Jin-Ha Yoon,Jong-Uk Won 대한직업환경의학회 2022 대한직업환경의학회지 Vol.34 No.-

Background: Recently, there has been a call to improve the holistic welfare of dependent contractors (DCs). Thus, our study examined the relationship between DCs and mental health symptoms and how this relationship was modified by age, sex, and income status of workers. Methods: A total of 27,980 workers from the Fifth Korean Working Conditions Survey are included in our study. The participants who reported having depression or anxiety over the last 12 months are defined those who had mental health symptoms. We performed exact matching for age group and sex, followed by conditional logistic regression with survey weights. Finally, stratified analyses by age, sex and income level were conducted. Results: DCs were found to be at increased risk of depression/anxiety compared to other workers. The odds ratio (OR) is 1.52 (95% confidence interval [CI]: 1.06–2.17). In the stratified analyses, vulnerable groups were middle-aged (OR [95% CI]: 1.68 [1.10–2.54]), female (OR [95% CI]: 1.85 [1.20–2.84]), and low-income (OR [95% CI]: 3.18 [1.77–5.73]) workers. Conclusions: Our study’s results reinforce those of other studies that show that DCs are at greater risk of experiencing mental health issues than other workers and that and this risk is greater for middle-aged, female, and low-income workers. These results suggest that appropriate policy efforts should be made to improve the psychological well-being of DCs.

풍선 확장술로 치료한 담관결석과 동반된 총담관 막양구조

백성민 ( Sung Min Baek ),김동욱 ( Dong Uk Kim ),장선미 ( Sun Mi Jang ),송병구 ( Byeong Gu Song ),박종만 ( Jong Man Park ),이대성 ( Dae Sung Lee ),김중근 ( Joong Keun Kim ),황경림 ( Kyung Lim Hwang ) 대한췌장담도학회 2014 대한췌담도학회지 Vol.19 No.3

Bile duct web is very rare disease and it`s etiology is controversial. Some webs are occurred in the presence of chronic inflammation, frequently associated with bile duct stone, but others are thought to be congenital. Many patients with bile duct web are asymptomatic, but they sometimes present symptom of biliary obstruction and cholangitis. It can be diagnosed by endoscopic retrograde cholangiopancreatogram, typically appearing as thin and shelf like radiolucent ring. We report a case of the common bile duct web with bile duct stones diagnosed by Endoscopic retrograde cholangiopancreatography (ERCP) in a 65-year-old man. The patient was treated by balloon dilatation successfully.

Residual Polar Motion excluding Chandler and Annual components

Na, Sung-Ho,Baek, Jeong-Ho,Kwak, Young-Hee,Yoo, Sung-Moon,Cho, Jung-Ho,Cho, Sung-Ki,Park, Jong-Uk,Park, Pil-Ho 한국우주과학회 2011 한국우주과학회보 Vol.20 No.1

원발급성폐쇄각발작에서 레이저홍채절개술에 이은 조기 수정체적출술 병합치료의 효과

백성욱(Sung Uk Baek),최동철(Dong Chul Choi),이경화(Kyung Wha Lee) 대한안과학회 2016 대한안과학회지 Vol.57 No.7

목적: 원발급성폐쇄각발작 환자에서 발작안에 레이저홍채절개술만 시행한 환자군과 레이저홍채절개술에 이은 조기 수정체적출술을 시행한 환자군에 대해 장기간의 안압 변화를 알아보았다. 대상과 방법: 후향적 의무기록 분석을 통해 원발급성폐쇄각발작으로 내원하여 발작안에 레이저홍채절개술만을 시행한 환자군(A군)과 1달 이내 레이저홍채절개술에 이은 수정체적출술을 시행한 환자군(B군)을 대상으로 조사하였다. 내원한 초진 시부터 12개월까지 A, B군에 대해 안압 변화를 알아보았다. 결과: 총 대상 환자는 99명으로 A군 37명, B군 62명이었다. A, B군 간의 각 시기별 평균 안압은 수술 후 1개월째 유의한 차이를 보이지 않았으나, 3개월, 6개월, 12개월째 B군이 A군에 비해 유의하게 낮은 양상을 보였다(p=0.003, <0.001, <0.001). 두 군 간 안압의 재상승(IOP ≥ 21 mmHg) 빈도는 3개월, 6개월, 12개월에 각각 A군은 3명(8.11%), 5명(13.51%), 5명(13.51%), B군 0명, 2명(5.41%), 1명 (1.61%)으로 유의하게 B군에 안압의 재상승 빈도가 낮았다(p=0.050, 0.038, 0.026). 결론: 레이저홍채절개술에 이은 조기 수정체적출 시행 후 1년간의 관찰 결과 성공적으로 안압 조절이 가능하였으며 레이저홍채절개술만 시행한 군에 비해 안정적인 결과를 보였다. 본 연구를 통해 원발급성폐쇄각발작 환자에서 백내장이 동반된 경우 레이저홍채절개술에 이은 조기 수정체적출술은 장기적 치료 효과 측면에서 권장할 만한 방법으로 판단된다. <대한안과학회지 2016;57(7):1126-1133> Purpose: To evaluate long-term change in intraocular pressure (IOP) in eyes undergoing laser iridotomy (LI) and early phacoemulsification after LI in patients with acute angle-closure glaucoma (AACG). Methods: The retrospective, comparative chart review included patients with AACG, Group A who underwent only LI and Group B who underwent early phacoemulsification within 1 month after LI. Patients were followed up on day 1; week 1; and months 1, 3, 6, and 12 after LI. IOP changes were studied. Results: This study included a total 99 eyes from 99 patients, 37 in group A and 62 in group B. The mean IOP were not significantly different between the two groups at the initial visit or 1 month later. However, group B showed a consistently lower mean IOP that that of group A at 3, 6, and 12 months (p = 0.003, <0.001, <0.001, respectively). The prevalence of IOP increase to greater than 21 mmHg was 3 (8.11%), 5 (13.51%), and 5 patients (13.51%) in group A and 0, 2 (5.41%), and 1 patients (1.61%) in group B at 3, 6, and 12 months, respectively. Group B showed a significantly lower prevalence of IOP increase (p = 0.050, 0.038, 0.026). Conclusions: We found that patients treated with early phacoemulsification after LI had better outcomes of well-maintained IOP compared to those undergoing LI alone. For AACG patients with coexisting cataract, early phacoemulsification after LI can be considered as a reasonable treatment to maintain IOP. J Korean Ophthalmol Soc 2016;57(7):1126-1133

순환유동층 연소로에서 하수슬러지/목질계 바이오매스 혼합펠릿의 연소: 오염물질 저감을 위한 산화제 변화 영향

백건욱(Geon-Uk Baek),문지홍(Ji-Hong Moon),조성호(Sung-Ho Jo),박성진(Sung-Jin Park),김재영(Jae-Young Kim),최유진(Yu-Jin Choi),배달희(Dal-Hee Bae),Nguyen Hoang Khoi,이규복(Kyubock Lee),문태영(Tae-Young Mun) 한국연소학회 2020 한국연소학회지 Vol.25 No.1

Combustion experiment for pellets of sewage sludge and woody biomass blend was conducted in a pilot-scale circulating fluidized bed combustor (CFBC) consisting of the riser, two hot cyclones and a loop-seal to reduce pollutant emission in exhausted flue gas. To achieve them, the effect of the oxidant variations, such as superficial velocity, equivalence ratio(ER: 1.2, 1.3, 1.4) and combustion atmosphere (air-fired and oxy-fired) was evaluated. As pollutant emissions in flue gas, SO₂, NO, CO, CO₂, HCl, odor contaminants and leaching behavior of heavy metals were analyzed. As a result, to stably operate combustion of pellet mixed with sewage sludge and woody biomass as alternative renewable fuel in a CFBC system, the superficial velocity in the riser had to be kept under 6 m/s and the equivalence ratio was proper around 1.3-1.4. All odor contaminants formed at these operating conditions met the domestic air pollutant standards. Heavy metals in fly ash met the environment ministry’s standard. Additionally, compared to air-firing, SO₂, NO and CO as precursors of fine particles during oxy-firing were reduced by 70.8, 77.1 and 38.2%, respectively.

4차산업혁명시대의 서비스 감성품질

백창화 ( Chang-hwa Baek ),임성욱 ( Sung-uk Lim ),강태욱 ( Tae-uk Kang ),윤성필 ( Sung-pil Yoon ) 한국품질경영학회 2017 한국품질경영학회 학술대회 Vol.2017 No.2