The Effect of Electronic Cigarette Uses in Patients with Acute and Chronic Respiratory Disease

( Yeonseok Choi ),( Jae Yeol Kim ),( Eun Mi Chun ),( Sang Haak Lee ),( Joo Hun Park ),( Jong Sook Park ),( Jae-woo Jung ),( Hye Jung Park ),( Hye Seon Kang ),( Dong Il Park ),( Hye Sook Choi ) 대한결핵 및 호흡기학회 2021 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.129 No.0

Purpose The number of electronic cigarette (e-cigarette) users has steadily increased. It has been noted that e-cigarette use has negative effects on immune-related gene expression, respiratory symptoms, and pulmonary system of healthy adults. This study aimed to investigate the effects of e-cigarette uses on patients with acute or chronic respiratory disease, comparing groups with different smoking history. Methods Cross-sectional survey data from patients with acute or chronic respiratory disease of 9 university hospitals in South Korea was analyzed. Patients were categorized into three groups: never smokers, smokers (current smokers or former smokers of combustible cigarettes only), and e-smokers (current smokers or former smokers of e-cigarettes regardless of combustible cigarettes use). Results A total of 405 patients (133 never smokers vs. 133 smokers vs. 139 e-smokers) were included in this study. Among e-smokers, 131 (94.2%) had smoking history of combustible cigarettes, and 77 (55.4%) were able to reduce the number of daily combustible cigarettes smoked (10.5 cigarettes per day) but that of e-cigarettes was increased (11.8 cigarettes per day). In multivariable analysis, e-smokers were associated with higher EQ-5D-5L score and FEV1, and lower SGRQ score, but more likely to have chronic bronchitis, compared to smokers. Conclusions In our study, most of e-smokers have smoking history of combustible cigarettes without advantage to smoking cessation and they are associated with chronic bronchitis. Considering these effects in patients with acute or chronic respiratory disease, our study suggests that e-cigarette smoking has potential negative health effects following persistent smoking and long-term follow-up data is warranted.

Effect of long-term azithromycin therapy in COPD patients with or without bronchiectasis

( Yeonseok Choi ),( Sun Hye Shin ),( Hyunkyu Cho ),( Noeul Kang ),( Junsu Choe ),( Jiyeon Kang ),( Hyun-il Gil ),( Hye Yun Park ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-

Purpose: Long-term azithromycin treatment is recommended for chronic obstructive pulmonary disease (COPD) patients with frequent exacerbation. Bronchiectasis (BE) is a common comorbid condition in patients with COPD, for which long-term azithromycin is effective in preventing exacerbation. This study aimed to compare the effect of long-term azithromycin in COPD patients according to the coexisting BE. Methods: COPD patients who received azithromycin for more than 12 weeks were retrospectively identified at single referral hospital. COPD was defined as post-bronchodilator FEV1/FVC < 0.7 and BE was determined using computed tomography. Clinical characteristics and the treatment outcome of long-term azithromycin were compared between COPD with BE and COPD without BE. Results: Of total 59 patients, 43 had COPD with BE and 16 had COPD without BE. Compared to the group without BE, those with BE were more likely to be younger, female, and never-smokers. Median duration of azithromycin was 451 (IQR 230-755) days and only 3 (5.1%) patients experienced adverse event. At 12 months of azithromycin treatment, development of acute exacerbation was significantly lower in group with BE than those without BE (46.5% vs. 87.5%, p = 0.005). COPD assessment test (CAT) score also significantly improved in group with BE than those without BE (-4.0 vs. +1.5, p = 0.055). Conclusions: In COPD patients with frequent exacerbation, those with coexisting BE could benefit more from long-term azithromycin treatment, in terms of exacerbation prevention and quality of life improvement.

A Suggestion for the Efficient Disposal of Old Clothes in Korea

Yeonseok Choi,Sangkyu Choi,Yeonwoo Jung,Soyoung Han,Nguyen Quynh 한국신재생에너지학회 2023 AFORE Vol.2023 No.11

The Incidence and Risk Factors of Chronic Pulmonary Infection after Radiotherapy in Patients with Lung Cancer

( Yeonseok Choi ),( Jae Myung Noh ),( Kyung-jong Lee ),( Sang-won Um ),( Hojoong Kim ),( Byeong-ho Jeong ) 대한결핵 및 호흡기학회 2020 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.128 No.0

Background Lung cancer patients experiencing chronic pulmonary infection (CPI) is increasing with their improved survival. Radiotherapy, one of treatment modalities of lung cancer, is associated with damage to anatomic barrier and immune defects, which may cause infectious complication. This study aimed to investigate cumulative incidence and factors associated with CPI development after radiotherapy for lung cancer. Methods We retrospectively analyzed 1,872 patients between 2010 and 2014, who received radiotherapy for lung cancer, had a minimum follow-up period of 3 months after radiotherapy, and did not have CPI at the time of radiotherapy. CPI was defined as pulmonary tuberculosis, non-tuberculous mycobacterial pulmonary disease, chronic pulmonary aspergillosis, and pulmonary actinomycosis. The cumulative incidence of CPI and overall survival (OS) were estimated using the Kaplan- Meier Method, and a multivariable Cox proportional hazard analysis was performed to identify factors associated with CPI development. Results The median follow-up period was 2.33 years with a 55.6% 2-year OS rate. CPI was developed in 59 patients with cumulative incidences of 1.1%, 3.4%, 5.0%, and 6.8% at 1, 3, 5, and 7 years, respectively. In multivariable analysis, low body mass index, history of pulmonary tuberculosis, chronic heart disease, or radiation pneumonitis, and using inhaled corticosteroid were independent risk factors for CPI development. Conclusions The cumulative incidence of CPI after radiotherapy for lung cancer showed its increasing trend during the follow-up. Therefore, close follow-up regarding CPI development could be beneficial in patients with risk factors.

폐의류 처리 개선방안에 관한 연구

최연석 ( Yeonseok Choi ),최상규 ( Sangkyu Choi ),한소영 ( Soyoung Han ),정연우 ( Yeonwoo Jung ) 한국폐기물자원순환학회 2022 한국폐기물자원순환학회지 Vol.39 No.5

Globally, only 15% of discarded old clothes are recycled, while the remainder is incinerated or dumped in landfills, resulting in severe deterioration of air and land quality. Korea’s old clothes export business boomed and expanded until 2013. As a result, there were not any social difficulties, such as “Not in My Backyard” (NIMBY), nor a lack of in-country landfill sites to dispose of old clothes. However, China’s export of old clothes has been surging since the early 2010s and caused an oversupply of old clothes in the world market. This resulted in the problematic management of the related companies as well as the old clothes disposal problem in Korea. Furthermore, the government’s administration system for old clothes has some issues, such as incorrect statistics of discarded amounts, unclear classification of textile wastes, and a lot of unlisted companies in the field. This study retrieved the total amount of discarded old clothes in Korea through related references and compared it with other countries. Additionally, the physicochemical properties of old clothes were analyzed to determine their suitability for bio-SRF. Finally, a legislative system for old clothing in Korea was reviewed, and some modifications were suggested to support related industries and to prepare for the upcoming old clothing disposal problem.

바이오원유 제조를 위한 Palm Kernel Shell의 급속열분해에서 바이오매스 입자크기의 영향

최연석 ( Yeonseok Choi ),최상규 ( Sangkyu Choi ),김석준 ( Seockjoon Kim ),한소영 ( Soyoung Han ),정연우 ( Yeonwoo Jeong ) 한국신·재생에너지학회 2017 신재생에너지 Vol.13 No.4

Biomass is considered one of the most promising renewable energy sources, which are being actively researched due to the depletion of fossil fuels and the global warming issue. Biocrude-oil can be produced through the fast pyrolysis of various biomass feedstocks, such as wood, crops and agricultural and forestry residues. Because the heat transfer from the hot sand to the biomass particles is important in the fast pyrolysis process, the particle size is one of the key factors involved in controlling the fast pyrolysis process. In this study, PKS (Palm Kernel Shell) was used for fast pyrolysis to study the effect of the biomass particle size on the fast pyrolysis characteristics in a tilted-slide reactor with a biomass capacity of 20 kg/h. The raw biomass was crushed and ground first, and the resulting particles were sieved into three ranges of particle size, d < 0.5 mm, 0.5 mm < d < 1.0 mm, and 1.0 mm < d < 2.0 mm. At a low pyrolysis temperature, the biocrude-oil yield increased with increasing particle size, while at medium and high temperatures the yield did not show much variation with the particle size. The heating value of the biocrude-oil increased with increasing particle size at low temperature, while it decreased significantly at high temperature.

국내에서 발생하는 폐의류의 처리 개선 방안

최연석(Yeonseok Choi),최상규(Sangkyu Choi),한소영(Soyoung Han),정연우(Yeonwoo Jung) 한국신재생에너지학회 2023 한국신재생에너지학회 학술대회논문집 Vol.2023 No.6

펠렛형 폐기물 고형연료의 저장 특성 연구

최연석(Choi, Yeonseok),김영재(Kim, Yeongjae),한소영(Han, Soyoung),정민홍(Jeong, Minhong) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

RDF는 장기저장이 가능한 것이 특징 중의 하나이지만, 우리나라보다 앞서 대량저장을 시작한 일본의 RDF 저장 사일로에서 폭발사고가 발생한 사례가 있어, RDF를 실제로 저장하여 RDF 온도 및 가연성가스 발생상황 등을 장기간 감시 측정하여 사일로 안전관리지표를 도출하였다. 실험에 사용한 RDF 저장조는 직경 3.1m, 높이 11.4m의 사일로방식으로 제작하였다. RDF 저장량은 70m³이었으며, 저장기간은 475일이었다. 사일로에는 15개의 열전대를 설치하여 사일로 표면, 직경방향 1.2m 지점 및 기온을 측정하여 수직방향 및 수평방향의 온도변화를 분석하였다. 가스 샘플링포트는 온도측정지점과 동일한 위치 설치하여 진공펌프로 흡인하여 테트라 백에 포집하여 GC로 분석하였으며, 가스샘플링은 17회 실시하였다. 비교적 대형 저장설비이고 RDF가 열전도성이 낮은 물질임에도 불구하고 사일로 내부온도는 기온보다는 높았지만, 기온의 영향을 많이 받아 7월에 정점, 1월에 하점을 나타내는 사인곡선과 같은 패턴을 보였다. 측정지점별 온도차는 수평방향 보다 수직방향에서 높게 나타났으며, RDF층으로 전열 및 축열이 진행되고 생화학반응을 촉진시키는 상승작용의 결과로 월평균온도가 49?C를 나타내는 지점도 있었다. 실제 사일로는 RDF의 투입과 배출이 연속적으로 진행되어 방열이 이루어지므로 하계에 대량저장을 실시하지 않는 한 RDF층 내부에서 생화학적 반응열이 생성되더라도 40?C를 상회할 가능성은 매우 희박할 것으로 판단된다. RDF 저장시 발생하는 가스는 대부분 CO₂였으며, 미량이지만 H₂, CO, CH₄도 검출되었다. 가연성 가스는 저장 후 2개월 동안은 발생하지 않았으며, 하계에는 타 계절에 비해 상대적으로 고농도로 검출되었다. 발생가스와 온도 및 CO₂와 H₂농도의 상관성은 높게 나타나지 않았지만, 정의 상관관계를 나타내었다. 저장한 RDF의 성상(수분, 발열량, 분화물)은 실험개시 전의 RDF분석결과와 실험종료 후 분석결과에서는 큰 차이가 나타나지 않았다. 따라서 RDF의 안전 저장을 위해서는 (1) 반입되는 RDF성상관리, (2) RDF가 2개월 이상 장기간 체류하는 데드스페이스가 발생하지 않고 선입선출이 확보되는 저장조 설계, (3) 사일로 내부에 최소 3개 이상의 지점에서 온도를 측정하여 상시감시하고 40?C이하로 관리, (4) 발생가스는 CO, CO₂, H₂, CH₄ 등의 가연성가스를 모두 측정 감시하는 것이 바람직하지만, 최소 CO₂와 H₂는 상시감시하고 각각 1%와 100ppm 미만으로 관리, (5) 배풍기 등을 이용한 상시 환기실시, (6) 하계에는 대량저장이 이루어지지 않도록 저장조 운용계획 수립 등을 실시해야 한다.

다단회전식 건조장치에 의한 돈분뇨 탈수케이크의 건조 실증실험에 관한 연구

최연석(Yeonseok, Choi),김영재(Youngjae, Kim),최상규(Sangkyu, Choi),정연우(Yeonwoo, Jeong),정두수(Doosoo Jeong) 한국신재생에너지학회 2014 한국신재생에너지학회 학술대회논문집 Vol.2014 No.05

생활폐기물고형연료(RDF) 제조기술 경제성 평가

최연석(Choi, Yeonseok),최항석(Choi, Hangseok),김석준(Kim, Seockjoon) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

국내 최초의 생활폐기물고형연료(RDF) 생산플랜트인 원주시 RDF플랜트의 2009년도 운영실적을 정리하여 폐기물 처리단가를 분석하였으며 에너지 생산 효과도 분석하였다. 실적분석에 사용된 자료는 원주 RDF플랜트 위탁운영업체가 운영비를 청구 및 정산하기 위해서 원주시에 상시 측정 및 보고하는 항목으로서, 내용은 트럭으로 플랜트에 반입되는 폐기물 전체량, RDF생산 전체량, 불순물 매립 전체량, 건조 및 탈취용 연료사용 전체량, 전기사용 전체량 등이다. 2009년도 원주시 RDF플랜트에 반입된 폐기물 량은 총 17,504톤이었고, RDF를 총 7,044톤 생산하였으며, 4,120톤의 불연물을 선별하였다. 1년간 사용한 건조 및 탈취용 연료는 총 596,268 리터였으며 연료인 부생유의 가격은 리터 당 평균 864.6원이었다. 사용한 전기량은 총 2,435,397 kWh였고, 이 중에서 성형공정에 사용된 전기량은 총 사용량의 19%였다. 이상의 기록자료들을 분석해 본 결과, 폐기물 1톤을 처리하는데 전기 비용이 14,334원이었고, 연료비가 29,452원이었다. 여기에 폐기물 1톤당 불연물 매립비 6,573원과 위탁인건비를 합하면 폐기물 1톤당 처리비용은 약 116,573원으로 나타났다. 현재 원주시 RDF는 톤당 25,000원에 판매되고 있으므로 이 비용을 감안하면 폐기물 1톤당 처리비용은 105,298원으로 산출되었다. 현재 알려진 유사 규모의 소각로 운영비가 폐기물 1톤당 136,736원인데, 이것은 RDF기술보다 31,438원/톤-폐기물 정도 처리비용이 비싸다. 따라서 100톤 이하 규모의 폐기물처리시설 설치를 할 경우에는 RDF 시설이 경제적으로 타당함을 나타낸다. 원주시 RDF플랜트의 물질수지를 분석해 본 결과, RDF생산 수율은 40.2%였으며 총 투입된 에너지는 8,0587 Gcal였다. 생산된 에너지 총량은 RDF발열량 4,500 kcal/kg으로 했을 때 31,699 Gcal로 나타났다. 투입대비 생산에너지 비율은 25.4%로 계산되었고, 전기의 발전효율을 40%로 감안했을 경우에는 35.3%로 계산되었다. 성형하는데 사용되는 총 에너지는 전체 투입에너지의 4.9%로 나타났고, 비용으로는 폐기물 1톤당 2,723원 이었다.