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Dong‑Su Bae,Un‑Bong Baek,Seung‑Hoon Nahm,Ilguk Jo 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2
This study investigated the effect of the hydrogen charging time on the hydrogen embrittlement of hot-rolled and acceleratedcoolingtreated API X70 steel by using the electrochemical hydrogen charging method. Tensile and V-notch Charpy impacttest were completed for the specimens of hydrogen charged for 0, 2, 4, and 10 h, and then microstructural observation wereperformed. The tensile and yield strength tended to decrease slightly and the total elongation started to decrease rapidly up to2 h charging time and then these gradually decreased with the hydrogen charging time. The post-uniform elongation increasedslightly after the holding time of 2 h due to the occurrence of two-step stress reduction phenomenon and its mechanismhas suggested. The effect of the hydrogen embrittlement on impact absorption energy according to the hydrogen chargingtime were also investigated. The fracture surface of the hydrogen charged ones are generally composed of cleavage fracturesurfaces. It was demonstrated that the external cracks were formed on the outside of tensile tested specimen and the externalshape of the fracture portion was fractured without large elongation at hydrogen charged specimens.
서울지역에서의 VOCs 오염원 기여도 추정에 관한 연구
봉춘근,윤중섭,황인조,김창녕,김동술 한국대기환경학회 2003 한국대기환경학회지 Vol.19 No.4
A field study was conducted during the summer time of 2002 to determine compositions of volatile organic compounds (VOCs) emitted from vehicles and to develop source emission profiles that is applied to CMB model to estimate the source contribution of certain area. Source emission profile is widely used for the estimation of source contribution by the chemical mass balance model and have to be developed applicable fur the large1 area of estimation. This study was aimed to develop source emission profile and estimation of source contribution of VOCs after application of the chemical mass balance (CMB) receptor model. After considering the emission inventory and other research results for the VOCs in Seoul, Korea, the sources like vehicle emission(tunnel), gas station (gasoline, diesel), solvent usage (painting operation, dry cleaning, graphic att), and gas fuels were selected for the major VOCs sources. Furthermore, ambient air samples were simultanceusly collected from 09:00 to 11:00 for four days at eight different official air quality monitoring sites as receptors in Seoul during summer of 2001. Source samples were collected by canisters, and then about seventy volatile organic compounds were analyzed by gas chromatography with flame ionization detector (GC/FID). Based on both the developed source profiles and the database of the receptors, CMB model was intensively applied to estimate mass contribution of VOCs sources. Examining the source profile from the vehicle, the portion of alkanes of VOCs was highest, and then the portion of aromatics such toluene, m/p-xylene were followed In case of gas fuel, they have their own components: the content of butane. propane. ethane was higher than any other component according tn the fuel usage. The average of the source apportionment on VOCs for 8 sites showed that the major sources were vehicle emission and gas fuels. me vehicle emission source was revealed as having the highest contribution with an average of 49.6% and followed by solvent with 21.3%, gas fuel with 16.1%, gasoline with 13.1%.
홍동민,천봉권,장희경 고신대학교 의과대학 2009 고신대학교 의과대학 학술지 Vol.24 No.2
Backgroud: Colonic and rectal cancers recently increase in incidence and motality in Korea. Although a variety of therapeutic modality has been applied, the result of therapy for the patients having lymph node metastases is not good. Especially the patient can have lymph node metastases in spite of early colonic and rectal cancer, and high recurrence rate is expected if non-radical therapy without adjuvent modality is applied to these patient in follow-up period. Therefore it is aimed to identify the risk factor affecting lymph node metastasis and to evaluate the possibility of the nodal metastases preoperatively and postoperatively. Methods: This retrospective study of 463 patients having suffered lower anterior resection, Miles operation or colectomy for colonic or rectal adenocarcinoma. Invasiveness, size of the carcinoma, age, vascular invasion, lymphovascular invasion, perineural invasion , sex, and grade of the carcinoma was evaluated as the possible risk factors of lymph node metastases. Results: Resected colonic and rectal adenocarcinoma reveals regional lymph node metastases in 46.3% cases. The nodal metastasis is statistically correlated with increase in tumor stage, tumor grade, and presence of lymphovascular and perineural invasion, and older age (p<0.05). Conclusion: Invasiveness, tumor grade, age, presence of lymphovascular invasion and perineural invasion would be risk factors expecting the regional lymph node metastasis in the colonic and rectal cancers. Therapeutic modality should be determined especially in tumor stage more than T1 because regional lymph node metastasis is expected.
봉춘근,김동술,김영두,김광래 경희대학교 환경연구소 2002 環境硏究 論文集 Vol.11 No.-
This study was fulfilled to evaluate the durability of VOCs for different sampling methods. The sampling methods widely used to collect atmospheric VOCs are Canister method (EPA method TO-141, Absorbtion tube method (EPA method TO-17), and Tedlar-bag method, and those methods are used in this study. The samples were analyzed after 0, 1, 3, 7, 15, 30 days to figure out the durability of components while keeping under low temperature (4℃) and room temperature (about 20 ℃). Each sample collected by above sampling method was analyzed by high resolution gas chromatography (GC) with flame ionization detector (FID). The test results were shown that the compounds in canisters and absorbtion tubs were stable, but the ones in tedlar-bags were not stable. Heavy components such as Toluene, m/p-Xylene in absorbtion tubes were kept their stability for a long time longer than the ones in canisters. However, the reducing rates of heavy components in canisters were not bigger than those of Tedlar-bags. The VOCs sample collected and stored in tedlar-bag are unstable for analysis, even after a days. As a result of this study, it is found that Canister method and Absorbtion tube method are reliable for collection and storage for a variety of ozone precursors compared to Tedlar-bag method. It is strongly recommended that the samples collected using Tedlar-bag need to be analysed shortly after sampling.
군 훈련병의 스트레스, 성인 주의력결핍 과잉행동장애 증상과 자살사고의 연관성에 관한 연구
이동윤,이철순,박철수,손진욱,김봉조,차보석,이소진 대한생물치료정신의학회 2011 생물치료정신의학 Vol.17 No.2
Objectives:This study is conducted to investigate the effect of Attention Deficit and Hyperactivity Disorder(ADHD) symptoms on stress and suicide idea among 224 conscripts. Methods:Total number of subject is 224 conscripts. We evaluate symptoms of adult ADHD with Korean-Wender Utah rating scale(K-WURS) and Korean adult attention-deficit/hyperactivity disorder scale(K-AADHDS), stress with Brief Encounter Psychosocial Instrument-K(BEPSI-K), suicide idea with Scale for suicide ideation(SSI) after basic military training. Multivariate logistic analysis with backward stepwise selection is performed to evaluate risk factors of stress. Multiple linear regression analysis with stepwise selection is performed to evaluate association of suicide idea with adult ADHD symptoms. Results:Stress is significantly associated with K-WURS score, K-AADHDS score and SSI score(p<0.01, p<0.05, p<0.01). K-WURS score are significant risk factor of stress after basic military training(p<0.05, O.R : 1.034, 95% CI : 1.005-1.065). And K-WURS score influence suicide idea after basic military training(p<0.05, β : 0.031). Conclusion:The result suggests that K-WURS score might be a risk factor of stress and could affect suicide idea.
봉정표,정윤규,이훈범,김주봉,이재화,나동균,김석원 大韓成形外科學會 1997 Archives of Plastic Surgery Vol.24 No.6
Hypopharyngo-esophageal cancer is usually found at late stage. Its main treatment is surgical intervention and it often requires radical resection. Reconstruction of the hypopharyngo-esophageal defect after the resection of carcinomas of the hypopharynx and the cervical esophagus has traditionally been carried out with deltopectoral or musculocutaneous flap. Another approach is to reconstruct the defect with the colon or stomach. Recent advances in microvascular surgical techniques have resulted in one stage reconstruction with free flap. Both jejunal free flap and radial forearm free flap is a good alternative for the reconstruction of hypopharyngo-esophageal defect. Six cases of the radial forearm flap and nine cases of the jejunal flap were used to reconstructed the hypopharyngo-esophageal defect in 15 patients. In jejunal free flap, upper margin was reconstructed with end to side anastomosis and lower margin with end to end anastomosis. In radial forearm free flap, we used trapezoid shaped flap and tubed by complete or partial tubing according to the condition of the defects. Stricture and fistula are troublesome complications. The complications were peritonitis(n=1) and fistula(n=1). We concluded that both forearm and jejunal free flap is a useful alternative in reconstruction of hypopharynx and cervical esophagus.