국적취득조건부 나용선(裸傭船)이 한국해운에 미친 영향에 관한 소고

이원철 한국해운학회 1988 해운물류연구 Vol.6 No.-

Benzylbenzenesulfonate와 三次아민의 反應에 關한 溶媒效果

李元哲 慶北工業專門大學 1981 論文集 Vol.18 No.-

The rate and activation parameters for the reaction of benzylbenzenesulfonate with tertiary amines such as pyridine, 4-aminopyridine and M. N-dimethylaniline has been measured in various solvents by conductometry. As a results, on the whole, the rate was increased in proportion to solvent polarity. Methanol, the most of all, was faster as the reaction rate is in contrast to dielectric constant is the push-pull mechanism. Activation parameters and isokinetic relationship between ?? and ?? indicated ?? characters in each solvents. In the case of methanol, when pKa of amine is very large, the reaction rate has been decreased because of nucleophilicity has been weakened by hydrogen bonding and the energy of desolvation has increased. The other correlative parameters between rate constant and solubility parameters, solvent parameter, dielectric constant, Et was obtained.

특집편집기

이원철 한국전자파학회 2018 전자파기술 Vol.29 No.6

한국인 호발암의 역학 - 위암, 간암, 대장직장암을 중심으로 -

이원철 대한소화기학회 1996 단기과정 Vol.1996 No.-

Does epithelioid angiomyolipoma have poorer prognosis, compared with classic angiomyolipoma?

이원철,최세영,이찬우,유상준,유달산,정인갑,송채린,김건석,홍범식,홍준혁,안한종,김청수 대한비뇨의학회 2018 Investigative and Clinical Urology Vol.59 No.6

Purpose: Classic angiomyolipoma (AML) is common benign kidney tumor. However, some studies have claimed that epithelioid angiomyolipoma (EAML) has malignant potential. We compared the patient characteristics and prognosis of EAML and classic AML to demonstrate predicting factors and poorer prognosis of EAML. Materials and Methods: The medical records of 231 patients who were diagnosed with EAML (n=27, 11.7%) or classic AML (n=204, 88.3%), were reviewed. All patients underwent computed tomography (CT) scans before operation or needle biopsy. We assessed the age, sex, tumor size, body mass index, comorbidities, and Hounsfield unit (HU) according to each CT phase. We defined the unfavorable group as patients with recurrence, metastasis and death due to tumor progression. Logistic regression analysis was used to predict EAML. Results: EAML patients were younger (41.2 years vs. 49.1 years, p=0.001), predominantly male (55.6% vs. 28.4%, p=0.005), and had a larger tumor (7.5 cm vs. 4.2 cm, p<0.001). The median pre-contrast HU was not significantly different between EAML and classic AML (29.9±23.7 vs. 14.7±41.0, p=0.071). In multivariable analysis, younger age (odds ratio [OR], 0.96; p=0.032), male sex (OR, 3.33; p=0.013), and tumor larger than 4 cm (OR, 3.8; p=0.009) were significant predictive factors. Five patients (18.5%) had unfavorable outcomes, two patients had lymph node metastasis, and three patients had lung metastasis. Conclusions: Patient and tumor characteristics can be helpful in determining the type of AML preoperatively. Younger age, male sex, and larger tumor mass may increase the possibility of diagnosing EAML. EAML has malignant potential and requires careful follow-up.

화학적 환경과 여성노동(Ⅰ)

이원철 가톨릭 대학 산업의학 쎈타 산업의학연구소 1987 韓國의 産業醫學 Vol.26 No.3

신용카드 추천을 위한 다중 프로파일 기반 협업필터링

이원철,윤협상,정석봉 한국산업경영시스템학회 2017 한국산업경영시스템학회지 Vol.40 No.4

Collaborative filtering, one of the most widely used techniques to build recommender systems, is based on the idea that users with similar preferences can help one another find useful items. Credit card user behavior analytics show that most customers hold three or less credit cards without duplicates. This behavior is one of the most influential factors to data sparsity. The ‘cold-start’ problem caused by data sparsity prevents recommender system from providing recommendation properly in the personalized credit card recommendation scenario. We propose a personalized credit card recommender system to address the cold-start problem, using multiple user profiles. The proposed system consists of a training process and an application process using five user profiles. In the training process, the five user profiles are transformed to five user networks based on the cosine similarity, and an integrated user network is derived by weighted sum of each user network. The application process selects k-nearest neighbors (users) from the integrated user network derived in the training process, and recommends three of the most frequently used credit card by the k-nearest neighbors. In order to demonstrate the performance of the proposed system, we conducted experiments with real credit card user data and calculated the F1 Values. The F1 value of the proposed system was compared with that of the existing recommendation techniques. The results show that the proposed system provides better recommendation than the existing techniques. This paper not only contributes to solving the cold start problem that may occur in the personalized credit card recommendation scenario, but also is expected for financial companies to improve customer satisfactions and increase corporate profits by providing recommendation properly.

화학적 환경과 여성노동(Ⅲ)

이원철 가톨릭대학 산업의학쎈타 산업의학연구소 1988 韓國의 産業醫學 Vol.27 No.4

시클로 중합에 의한 디프로파길 술폰으로 부터 전도성 고분자의 합성

李元哲 慶一大學校 1989 論文集 Vol.5 No.1

Cyclopolymerization of dipropargyl sulfone was carried out by various transition metal catalyst associated with cocatalytic organotin or organoaluninum compounds under various reaction conditions. The effects of monomer to catalyst mole ratio, solvent, cocatalyst, and temperature was also investigated. The high yield(99%) were obtained by PdCl₂as homocatalyst when the initial monomer concentration is 0.5 in the DMF solution. Poly(dipropargyl sulfone)(PDPS) obtained by PdCl₂was completely soluble in DMF and DMSO, whereas those prepared by WCl??, MoCl??, and other alkoxide catalyst were insoluble in any organic solvent. The electrical conductivity of I₂-doped polymer obtained by PdCl₂was 1.23×10??Ω??㎝??.

흰쥐의 중대뇌동맥 폐쇄 후 黃連解毒湯 투여가 대뇌반구 및 시상 위축에 미치는 영향

李源哲,尹相協,金善暎 東國大學校 1998 東國論叢 Vol.37 No.-

This study is supposed to find out the effect of Whangryunhaedogtang(黃連解毒湯) fractions on cerebral and thalamic atrophy following middle cerebral artery occlusion in rats. Permanent middle cerebral artery occlusion in rats results in infarction in the ipsilateral cortex. In this Ischemia model, severe shrinkage of the ipsilateral cerebral hemisphere and half of the thalamus was observed several months after surgery. These findings are consistent with retrograde neuronal degeneration due to thalamocortical fiber damage in ischemic cortical regions. We divided 18 rats into two groups [group greated with Whangryunhaedogtang(黃連解毒湯) fractions and non treated group] and then, investigated this phenomenon at intervals from 4 days to 3 months after the operation. After 3 months, in order to research the degree of shrinkage of cerebral and thalamus, we measured the left right ratio of cerebral hemisphere's area on each 2mm's slice level from the frontal pole of brain. At the same time, we also investigated the left: right ratio of thalamus's area on 9mm's slice level from frontal pole of brain by Imaging analysis system. Although we compared this sample group and control group by the result of investigation, we can't find out the difference at the left: right ratio of cerebral hemisphere's and thalamus'area. Therefore, these results demonstrate that Whangryunhaedogtang(黃連解毒湯) fractios has no effect on cerebral and thalamic atrophy in according to retrograde degeneration over a long period time after focal cerebral infarction. However, in order to study the effect of Whangryunhaedogtang(黃連解毒湯) on retrograde neuronal degeneration following infarction, it is needed that we study from an aspect of change of neuron in electron microscopy and neurontransmitter etc.