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공정플랜트 연교배관의 시스템응력 해석에 의한 구조 건전성 평가
정성용 ( Seong Yong Jeong ),윤기봉 ( Kee Bong Yoon ),팜반듀엣 ( Pham Van Duyet ),유종민 ( Jong Min Yu ),김지윤 ( Ji Yoon Kim ) 한국안전학회(구 한국산업안전학회) 2013 한국안전학회지 Vol.28 No.3
Process gas piping is one of the most basic components frequently used in the refinery and petrochemical plants. Many kinds of by-product gas have been used as fuel in the process plants. In some plants, natural gas is additionally introduced and mixed with the by-product gas for upgrading the fuel. In this case, safety or design margin of the changed piping system of the plant should be re-evaluated based on a proper design code such as ASME or API codes since internal pressure, temperature and gas compositions are different from the original plant design conditions. In this study, series of piping stress analysis were conducted for a process piping used for transporting the mixed gas of the by-product gas and the natural gas from a mixing drum to a knock-out drum in a refinery plant. The analysed piping section had been actually installed in a domestic industry and needed safety audit since the design condition was changed. Pipe locations of the maximum system stress and displacement were determined, which can be candidate inspection and safety monitoring points during the upcoming operation period. For studying the effects of outside air temperature to safety the additional stress analysis were conducted for various temperatures in 0~30℃. Effects of the friction coefficient between the pipe and support were also investigated showing a proper choice if the friction coefficient is important. The maximum system stresses were occurred mainly at elbow, tee and support locations, which shows the thermal load sontributes considerably to the system stress rather than the internal pressure or the gravity loads.
각막지형도를 이용한 새로운 비침습적눈물막파괴시간 검사의 신뢰도 평가
정성용(Seong Yong Jeong),이상범(Sang Bumm Lee) 대한안과학회 2016 대한안과학회지 Vol.57 No.9
목적: 비침습눈물막파괴시간 검사의 재현성을 평가하고 기존 안구건조증 지표와의 관계를 분석해 보고자 하였다. 대상과 방법: 안구건조증군 50명과 정상대조군 50명을 전향적으로 모집하였다. Keratograph 4 (Oculus, Wetzler, Germany)를 이용하여 눈물막 첫 파괴시간(non-invasive keratograph first break-up time, NIKf-BUT)과 평균 파괴시간(non-invasive keratograph average break-up time, NIKav-BUT)을 2회 반복 측정 후, 플루오레신 눈물막파괴시간(tear film break-up time with fluorescein, FBUT)을 측정하고 지표 간 상관관계를 분석하였다. NIKf-BUT와 NIKav-BUT의 급내상관계수와 곡선아래면적을 이용한 진단력을 평가하였다. 결과: NIKav-BUT는 두 군 모두 FBUT와 양의 상관관계를 보였다(dry eye; r=0.66, p<0.001 and control group; r=0.77, p<0.001). NIKf-BUT와 NIKav-BUT의 급내상관계수는 안구건조증군에서 각 0.72와 0.94였고, 대조군에서는 각 0.70과 0.91이었다. NIKav-BUT와 FBUT는 유의한 차이가 없었다. 곡선아래면적은 NIKf-BUT에서 0.917, NIKav-BUT에서 0.980이었다. 결론: NIKf-BUT와 NIKav-BUT는 재현성이 확인되었다. NIKav-BUT는 FBUT와 유의한 차이가 없었으며, 양의 상관관계를 만족하였다. 높은 진단력을 보인 NIK-BUT는 안구건조증 정도를 나타내는 새로운 지표로 유용하게 이용될 수 있을 것으로 생각된다. Purpose: To evaluate the repeatability of non-invasive tear film break-up time and identify its relationships with dry eye parameters. Methods: A total of 100 participants (50 with dry eye, and 50 in the control group) were enrolled prospectively. Non-invasive keratograph first (NIKf-BUT) and average (NIKav-BUT) break-up times were evaluated 2 times using Keratograph 4 (Oculus, Wetzler, Germany), and then tear film break-up time with fluorescein (FBUT) was measured. The correlation analyses were performed between non-invasive parameters (NIKf-BUT and NIKav-BUT) and FBUT. Intra-observer agreements of NIKf-BUT and NIKav-BUT were assessed using intraclass correlation coefficients (ICC). The receiver operating characteristic (ROC) curve technique was used to evaluate the non-invasive method in the diagnosis of dry eye. Results: The correlation analyses revealed positive correlation between NIKav-BUT and FBUT in both groups (dry eye; r = 0.66, p < 0.001 and control group; r = 0.77, p < 0.001). The ICCs of NIKf-BUT and NIKav-BUT were 0.72 and 0.94 in the dry eye, respectively, and 0.70 and 0.91 in the control group. NIKav-BUT was not different from FBUT in either group. The areas under the ROC curves of NIKf-BUT and NIKav-BUT were 0.917 and 0.980, respectively. Conclusions: The high ICCs verified the repeatability of NIKf-BUT and NIKav-BUT. NIKav-BUT showed no difference from FBUT and positive correlation with FBUT. NIK-BUT showed high diagnostic power and can be considered a new parameter to evaluate dry eye syndrome.
산화물 반도체형 가스센서의 선택성 향상을 위한 필터 연구 동향 및 전략
정성용 ( Seong-yong Jeong ) 한국센서학회 2024 센서학회지 Vol.33 No.1
Metal-oxide-based semiconductor gas sensors are widely used because of their advantages, such as high response and simple sensing mechanism. Recently, with the rapid progress in sensor networks, computing power, and microsystem technology, sensor applications are expanding to various fields, such as food quality control, environmental monitoring, healthcare, and artificial olfaction. Therefore, the development of highly selective gas sensors is crucial for practical applications. This article reviews the developments in novel sensor design consisting of sensing films and physical and chemical filters for highly selective gas sensing. Unlike conventional sensors, the sensor structures with filters can separate the sensing and catalytic reactions into independent processes, enabling selective and sensitive gas sensing. The main objectives of this study are directed at introducing the role of various filters in gas-sensing reactions and promising sensor applications. The highly selective gas sensors combined with a functional filter can open new pathways toward the advancement of high-performance gas sensors and electronic noses.
화염 분무 열분해법으로 합성된 Cr-Co<sub>3</sub>O<sub>4</sub> 나노입자 자일렌 가스센서
정성용 ( Seong-yong Jeong ),조영무 ( Young-moo Jo ),강윤찬 ( Yun Chan Kang ),이종흔 ( Jong-heun Lee ) 한국센서학회 2020 센서학회지 Vol.29 No.2
Xylene is a hazardous volatile organic compound that should be precisely measured to monitor indoor air quality. However, the selective and sensitive detection of ppm-level xylene using oxide-semiconductor gas sensors remains a challenge. In this study, pure and Crdoped Co<sub>3</sub>O<sub>4</sub> nanoparticles (NPs) were prepared using flame spray pyrolysis, and their gas-sensing characteristics to 5-ppm xylene at 250 °C were investigated. The 4 at% Cr-doped Co<sub>3</sub>O<sub>4</sub> NPs exhibited a high gas response to 5-ppm xylene (resistance ratio to gas and air = 39.1) and negligible cross-responses to other representative and ubiquitous indoor pollutants such as ethanol, benzene, formaldehyde, carbon monoxide, and ammonia. In this paper, the enhancement of the gas response and selectivity of Co<sub>3</sub>O<sub>4</sub> NPs to xylene by Cr doping was discussed in relation to the catalytic promotion of the gas-sensing reaction. This sensor can be used to monitor indoor xylene.
결절맥락막혈관병증에서 중심맥락막두께에 따른 애플리버셉트 유리체강내주입술의 효과 분석
이동훈(Dong hun Lee),정성용(Seong yong Jeong),문종원(Jong won Moon),이준엽(Jun yeop Lee),사공민(Min Sa gong) 대한안과학회 2016 대한안과학회지 Vol.57 No.10
목적: 결절맥락막혈관병증 환자에서 중심맥락막두께에 따른 애플리버셉트 유리체강내주입술의 효과 차이를 분석하고자 하였다. 대상과 방법: 본원에서 결절맥락막혈관병증으로 진단 받고 애플리버셉트 유리체강내주입술을 받은 환자 중 6개월 이상 경과 관찰이 가능했던 60명 60안의 의무기록을 후향적으로 분석하였다. 주사 전 측정한 중심맥락막두께에 따라 얇은 군, 중간 군, 두꺼운 군으로 나누고 주사 후 6개월 동안의 최대교정시력, 중심맥락막두께, 중심황반두께 및 최대 망막색소상피박리 높이의 변화와 3개월째 결절 폐쇄율, 6개월째 황반부종 소실률을 비교 분석하였다. 결과: 총 60안 중 얇은 군은 14안(23.3%), 중간 군은 33안(55.0%), 두꺼운 군은 13안(21.7%)이었으며, 주사 전 평균 중심맥락막두께는 각각 178.50 ± 28.42 μm, 287.03 ± 43.58 μm, 379.77 ± 17.09 μm였다. 세 군 간 초진 시 연령, 성비, 최대교정시력, 중심황반두께 및 최대 망막색소상피박리 높이는 유의한 차이가 없었다. 치료 6개월 후 최대교정시력은 얇은 군에서만 유의한 호전을 보였고 (p=0.005) 중간 군과 두꺼운 군에서는 호전은 되었지만 통계적 유의성은 없었다(p=0.063, p=0.692). 중심맥락막두께, 중심황반두께 및 최대 망막색소상피박리 높이는 세 군 모두에서 유의한 감소를 보였다. 중심맥락막두께가 얇을수록 첫 주사 후 3개월째 완전 결절 폐쇄율과 6개월째 황반부종 소실률이 높았다(p=0.013, p=0.004). 결론: 애플리버셉트 유리체강내주입술은 결절맥락막혈관병증의 치료에 있어서 효과적이었고, 중심맥락막두께가 얇을수록 더 좋은 치료 결과를 보였다. <대한안과학회지 2016;57(10):1577-1585> Purpose: To evaluate the effect of intravitreal aflibercept according to subfoveal choroidal thickness in patients with polypoidal choroidal vasculopathy (PCV). Methods: We retrospectively analyzed the medical records of 60 eyes from 60 patients with PCV treated with intravitreal aflibercept. The patients were followed for at least 6 months after the first injection. Using software, subfoveal choroidal thickness was manually measured as the distance from the hyper-reflective line of Bruch’s membrane to the chorioscleral interface on optical coherence tomography. The patients were divided into three groups based on subfoveal choroidal thickness. Visual acuity, subfoveal choroidal thickness, central macular thickness and largest pigment epithelial detachment (PED) height, polyp regression rate, and dry macula rate were evaluated to analyze the anatomical and functional outcomes. Results: Baseline mean subfoveal choroidal thickness were 178.50 ± 28.42 μm in the thin group (14 eyes, 23.3%), 287.03 ± 43.58 μm in the medium group (33 eyes, 55.0%), and 379.77 ± 17.09 μm in the thick group (13 eyes, 21.7%). Baseline age, sex, visual acuity, central macular thickness, and the largest PED height did not differ significantly among the three subgroups. Only the thin group showed significant improvement of visual acuity at 6 months (p = 0.005). Subfoveal choroidal thickness, central macular thickness, and largest PED height were significantly decreased after treatment in all subgroups and did not differ among the subgroups. Compared with the other groups, the thin subfoveal choroidal thickness group showed higher polyp regression rate at 3 months and higher dry macula rate at 6 months (p = 0.013 and p = 0.004, respectively). Conclusions: Intravitreal aflibercept injection was effective for the treatment of PCV, and thin subfoveal choroidal thickness was associated with better anatomical and functional outcomes. J Korean Ophthalmol Soc 2016;57(10):1577-1585