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디메틸포름아미드 노출 근로자의 요중 N-메틸포름아미드 분석시 GC-NPD와 GC-FID 방법간 비교
정다운,김현욱 가톨릭대학산업의학센타 산업의학연구소 1999 韓國의 産業醫學 Vol.38 No.1
This purpose of the this study was to compare the results of two analytical techniques, GC-NPD and GC-FID, of quantifying urinary NMF from 70 DMF exposed workers in synthetic resins, leather, and dye manufacturing industries. In addition, the relationship between conecntrations of airborne DMF and urinary NMF was investigated using samples collected from 12 workers. Airborne DMF was sampled using both charcoal and silicagel tubes. All urine specimens were collected both prior-to and at end-of workshifts. The results were as follows: 1. The detection limits of urinary NMF by GC-FID and GC-NPD were 0.043㎎/l and 0.009㎎/l, respectively. The recovery rates were 96.9% for the GC-NPD and 90.2% for the GC-FID methods. 2. Desorption efficiencies of DMF on Charcoal tubes were very poor with 32.96%, while those on silicagel tubes were marginally acceptable with 85.70%. 3. A statistically significant relationship between concentrations of airborne DMF and urinary NMF from 12 workers determined by GC-NPD (r=0.74) and by GC-FID (r=0.67) was observed. 4. Geometric mean concentrations of urinary NMF of the end-of-shift urines from 70 workers were 15.84㎎/g creatinine by GC-NPD and were 9.88㎎/g creatinine by GC-FID, respectivery. For the prior-to-shift samples, they were 6.05 ㎎/g creatinine by GC-NPD and 0.92㎎/g creatinine by GC-FID. These results of this study suggest that for collecting airborne DMF in the workplace, silicagel tubes should be utilized. For quantifying urinary NMF concentrations as a biological marker of DMF exposed workes, urine should be collected at the end-of-shift. Urinary NMF should be analyzed by GC-NPD because of its lower of detection and better precision than that of GC-FID.
시중에 판매되고 있는 아이스크림의 일반세균 및 대장균군 오염 실태
정다운,김영환,손종렬,변상훈 高麗大學校 倂設 保健大學 保健科學硏究所 2003 保健科學論集 Vol.29 No.1
Ice cream is a vastly consumed food enjoyed by a wide range of people. Therefore, it is easily accessible and amounts to hundreds of its kind. Ice cream is a ready-made food which could be served without undergoing cooking process and thus putting weight on its hygienic condition. And so we set out to conduct some research on the number of E-coli bactria contained in commercially sold ice creams. We applied Lactose broth method along with Desoxycholate agar method which enables us to verify the existence of E-coli bacteria and how much is contained. We focused our research on soft ice creams and aimed to seek out the degree to which they were contaminated by E-coli bacteria. 4 major distributors of soft ice cream out of 5 didn't meet the maximum allowance of E coli bacteria to be found. The number of general bacteria observed per 1 ㎖ of specimen must be held at less than 100,000, and this wasn't violated by any of the companies' samples. Yet on E-coli testing, all of K, L, B and M companies' samples respectively exceeded the permitted limits of bacteria to be detected.
제1유구치의 조기 상실로 인한 공간 변화에 대한 3차원적 분석
김지연,정다운,곽소연,유승은,박기태 大韓小兒齒科學會 2008 大韓小兒齒科學會誌 Vol.35 No.2
본 연구는 제1유구치의 조기 상실 시 공간 변화에 대한 분석을 위하여 3-Dimensional Laser Scanner를 이용하여 그 유용성을 평가하고자 하는 예비논문이다. 6세-8세 사이의 제1대구치가 맹출하여 확실한 교합 관계를 이루는 혼합치 열기 어린이 중 편측 제1유구치의 조기 발치가 필요한 6명의 발치 전 후의 모형을 이용하여 다음과 같은 결과를 얻었다. l. 유구치 공간변화는 상악은 실험군과 대조군 모두 현저한 감소를 보이지 않았고, 하악은 실험군에서 3명 중 2명에서 공간감소가 관찰되었다. 2. 치열궁 너비,치열궁 둘레는 초기모형과 최종모형에서 비슷한 값을 보였다. 3. 협설측 경사도 변화는 유견치에서는 상하악 모두 특별한 경향을 보이지 않았으며,제2유구치는 상악은 실험군과 대조군이 유사하였고,하악에서는 3명중 2명에서 실험군이 더 큰 설측경사도 변화를 보였다. 제1대구치는 하악에서 실험군이 더 큰 설측경사도 변화가 관찰되었다. 4. 근원심 경사도 변화 측정에서 유견치는 상하악 모두 특별한 경향이 관찰되지 않았고 제2유구치의 경우 하악에서 실험군이 더 큰 근심경사도 증가가 보였다. 제1대구치는 상악에서 실험군,대조군 모두 원심 경사도가 증가되었다. The purpose of this study was to evaluate a 3-Dimensional laser scanner for the space analysis after loss of a primary first molar. Six children with premature loss of a primary first molar were examined using study models taken before and after the extraction. The results were as follows: 1. There was no change in primary molar space after the extraction of a maxillary primary first molar However, 2 out of 3 children experienced primary molar space loss in extraction side of a mandibular primary first molar. 2. Arch width and arch perimeter showed no difference between initial and final model. 3. All primary canines did not show any changes in inclination. Maxillary primary second molars had similar changes in both extraction and control side. However, 2 out of 3 mandibular primary second molars in extraction side showed more lingual tipping compared to control side. Mandibular permanent first molars tipped more lingually in extraction side. 4. In angulation, primary canines showed nothing of significance. Mandibular primary second molars tipped more mesially in extraction side than in control side. Maxillary permanent first molars have increased distal angulation after extraction of primary first molars in both side.
Jung, Da Woon,Kim, Byung-Ok,Kim, Hong Kee,Lee, Yang,Nam, Sang Bok,Ryu, Sung Ju,Sung, Hyo Jin,Yun, Sang Jo Korean Mathematical Society 2016 대한수학회지 Vol.53 No.2
We study the structure of central elements in relation with polynomial rings and introduce quasi-commutative as a generalization of commutative rings. The Jacobson radical of the polynomial ring over a quasi-commutative ring is shown to coincide with the set of all nilpotent polynomials; and locally finite quasi-commutative rings are shown to be commutative. We also provide several sorts of examples by showing the relations between quasi-commutative rings and other ring properties which have roles in ring theory. We examine next various sorts of ring extensions of quasi-commutative rings.
ON REVERSIBILITY RELATED TO IDEMPOTENTS
Jung, Da Woon,Lee, Chang Ik,Lee, Yang,Park, Sangwon,Ryu, Sung Ju,Sung, Hyo Jin,Yun, Sang Jo Korean Mathematical Society 2019 대한수학회보 Vol.56 No.4
This article concerns a ring property which preserves the reversibility of elements at nonzero idempotents. A ring R shall be said to be quasi-reversible if $0{\neq}ab{\in}I(R)$ for a, $b{\in}R$ implies $ba{\in}I(R)$, where I(R) is the set of all idempotents in R. We investigate the quasi-reversibility of 2 by 2 full and upper triangular matrix rings over various kinds of reversible rings, concluding that the quasi-reversibility is a proper generalization of the reversibility. It is shown that the quasi-reversibility does not pass to polynomial rings. The structure of Abelian rings is also observed in relation with reversibility and quasi-reversibility.
REVERSIBILITY OVER UPPER NILRADICALS
Jung, Da Woon,Lee, Chang Ik,Piao, Zhelin,Ryu, Sung Ju,Sung, Hyo Jin,Yun, Sang Jo Korean Mathematical Society 2020 대한수학회논문집 Vol.35 No.2
The studies of reversible and NI rings have done important roles in noncommutative ring theory. A ring R shall be called QRUR if ab = 0 for a, b ∈ R implies that ba is contained in the upper nilradical of R, which is a generalization of the NI ring property. In this article we investigate the structure of QRUR rings and examine the QRUR property of several kinds of ring extensions including matrix rings and polynomial rings. We also show that if there exists a weakly semicommutative ring but not QRUR, then Köthe's conjecture does not hold.
Da-Woon Leem,Hyun-Ju Jung,Moon-Sung Hwang,Jung-Ah Shim,Hyun-Jung Kwon 보안공학연구지원센터 2016 International Journal of Software Engineering and Vol.10 No.3
As a variety of services are provided through mobile devices, there have been increasing security threats to mobile platforms and applications. Many mobile application security check methodologies are proposed to deal with such threats, but it is not clear exactly how the security vulnerabilities are inspected, and there is no correct methodology for such. One way to increase the execution rate of vulnerability check is to develop an automation tool that simplifies the process. Therefore, in this study, a work process of Android application vulnerability inspection was designed and a prototype of the automation tool for vulnerability inspection was implemented. Furthermore, the effectiveness of the implemented prototype was assessed through an actual application using the prototype.