도장작업시 유해인자들의 노출수준과 작업환경관리실태

이세기,문덕환,이채관,황용식,선병관,손병철,김대환,이창희,김휘동,이채언 인제대학교 백병원 2002 仁濟醫學 Vol.23 No.5

Objectives: For the purpose of preparing the fundamental data and assessing the status of exposure level of chemical substances in painting process. Methods and Materials: The author determined the concentration of organic solvents, lead(Pb), Chromium(Cr), and Toluene-2, 4-diisocyanate(TDI) in air of painting process to 90 industries classified by 15 types of manufacturing industry during a period from Jan. 1st 2001 to Dec. 31st 2001. Results: The results were as follows: 1. The geometric mean level of each chemical substance was 0.1706 ppm for exposure index in organic solvents, 0.0019㎎/㎥ for Pb, 0.0024 ㎎/㎥ for Cr, and 0.0004ppm for TDI, respectively. 2. The exposure level of each chemical substances by type of painting was the highest in dipping and brush painting for organic solvent, in spray-painting for TDI, and in spray gun-painting for Pb and Cr, respectively. 3. The exposure level of each chemical substances by type of local ventilation equipment was higher in enclosed and booth type for organic solvents. Cr, and TDI, and in exterior type for Pb, respectively than those of other types. 4. The exposure level of each chemical substances by type of hazardous material arresting media was higher in using water for organic substances, in using bag filter for Pb, TDI, respectively than those of other types. Conclusion: According to above results, this study suggests that the exposure level by type of industry exceeded the exposure level in wooden furniture and metal furniture manufacturing industry for organic solvents and Pb, respectively.

도금사업장의 작업환경의 유해인자 노출수준에 관한 연구

문덕환,도수영,이채관,황용식,선병관,손병철,김대환,이창희,김휘동,이채언 인제대학교 백병원 2002 仁濟醫學 Vol.23 No.5

Objective : For the purpose of preparing the fundamental data and assessing the status of exposure level of chemical substances and physical agents. Methods and Material : Such as noise, two types of dust, four types of metals, seventeen types of organic solvents, and four types of other materials classified by specific chemical substances in 21 metal product plating factories classified by 28 processes. The author determined exposure level on those hazardous materials from Jan. to Dec. 2001. Results : The results were as follows: 1. The exposure level for noise was exceeded to Threshold Limit Value(TLV) in the process of 6 cases of Machining, 5 and 4 cases of pre and post-buffing, and 6 cases of waterdrop-removing, the mean noise level of all of processes was not exceeded to compliance level. 2. The exposure level for dust was not exceeded to TLV at all. 3. The exposure level for Chromium(Cr) was exceeded to TLV in Chromium plating process, metal exposure level including Zinc(Zn), Manganese(Mn), and Lead(Pb) was not exceeded to TLV. 4. The exposure level of toluene in case of organic solvents was exceeded to TLV in 1 case of finishing/cleaning, coating/developing process, respectively. 5. The exposure level of four types of other materials classified by specific chemical substances were not exceeded to TLV. 6. The exposure level for dust and metal including Zn, Mn, and Pb was decreased in comparison with two results of air monitoring performed. There was no difference of the exposure level for Cr, noise, and four types of other materials classified by specific chemical substances, and the exposure level for organic solvents was slightly increased. 7. The exposure level for noise in factories employing more than 21 workers was higher than that for noise in foadtories employing less than 20 workers. The more workers, the lower exposure level in metal including Zn, Mn. The exposure level for Cr was increasing in factories employing more than 51 workers, and the more workers the lower exposure level in organic solvents. Conclusion : According to above results, this study suggests positive work environment managements in processes exceeding exposure limit value as well as continuously consecutive work environment management in processes not exceeding exposure limit value and revealing no chronological difference of exposure level should be needed.

TiN 박막 형성에 미치는 ion beam 조사 효과

안병건,추관식,문두수,안정식,김영대,김형자,이규용 釜慶大學校 2002 釜慶大學校 論文集 Vol.7 No.-

Low energy high current N_2 ion beam was used to modify the morphology and chemical composition of cemented carbide WC-Co(Co:10 wt%, TiC + TaC:15 wt%, WC:bal) hard material surface for the fabrication of the TiN thin film by sol-gel method. The effects of ion beam treatment on preparation of the TiN thin film by sol-gel mothod were investigated by XPS, SEM, AFM and GXRD. According to the N_2 ion beam bombardment, the surface roughness was increased and TiC binders in WC were dissolved. The dissolved Ti was recombind with nitrogen ion to form the TiN nucleuses which were acted as seeds for the forming of the TiN thin film on the cemented WC-Co surface. Besides, the sputter deposited Ti interlayer prevented the diffusion of TiO_2 sol into the porous WC-Co during the formation of TiN thin film.

유지 투석중인 만성 신부전환자에서 허혈성 심질환의진단 지표로서의 심장트로닌-I의 유용성

신병철,강대웅,정지용,류봉관,서영욱,김정인,김범윤,김현리,정종훈 朝鮮大學校 附設 醫學硏究所 2004 The Medical Journal of Chosun University Vol.29 No.1

Background : Coronary disease is highly prevalent in patient with end stage renal disease (ESRD) and account for much of their observed morbidity and mortality. Troponin-I consistently maintains a high sensitivity and specificity and is most sensitive marker for ischemic heart disease (IHD). Method : We examed 49 hernodialyzed patients (22 male, 27 female) without evidence of acute coronary syndrome (ACS) for 6 months. Biochemical markers were measured in serial predialysis blood samples. For analysis, we used two cardio-specific assays for troponin-T (cTnT) as well as for troponin-I (cTnI) and compared the results with CK-MB (reference value ≤ 4.0 ng/mL) concentration. Results : Myocardial ischemia was observed in 47% (23/49) of patients. cTnT level above 0.1 ng/mL. and cTnI level above 0.5 ng/mL, were observed in 22% (11/49) and 20% (10/49) of patients respectively. cTnI revealed significantly higher positive rate in patients with myocardial ischemia than the patients without myocardial ischemia (43 % vs 30%) (p<0.05). cTnT and CK-MB revealed no difference in positive rate between the patients with and without myocardial ischemia (cTnT : 30% vs 15% and CK-MB : 30% vs 19%). The sensitivity and specificity of cTnI to myocardial ischemia were higher than those of cTnT and CK-MB (sensitivity 43% vs 30% and 30%. specificity 100% vs 85% and 81%). Conclusion: Both cTnT and cTnI are useful in ruling out myocardial injury in chronic renal failure patients. But. cTnI is a more sensitivity and excellent specificity of ischemic heart disease than cTnT and CK-MB in hemodialyzed patients. In patients with ischemic heart disease, the presences of DM and advanced age were higher than those in patients without ischemic heart disease (p<0.05). Among the baseline characteristics old age, elevated LDH and diabeties were significant more frequent in the patients with elevation of cardiac troponin-I (p>0.5 ng/mL) than those with cardiac troponin-I (p<0.5 ng/mL), p=0.038, p=0.049, and p=0.045, respectively. Our results suggest that these cTnI is the potential diagnostic marker for the prediction of IHD in ESRD patients.

Direct Construction of Superoscillations

Dae Gwan Lee,Ferreira, Paulo Jorge S. G. IEEE 2014 IEEE transactions on signal processing Vol.62 No.12

<P>Oscillations of a bandlimited signal at a rate faster than its maximum frequency are called “superoscillations” and have been found useful e.g., in connection with superresolution and superdirectivity. We consider signals of fixed bandwidth and with a finite or infinite number of samples at the Nyquist rate, which are regarded as the adjustable signal parameters. We show that this class of signals can be made to superoscillate by prescribing its values on an arbitrarily fine and possibly nonuniform grid. The superoscillations can be made to occur at a large distance from the nonzero samples of the signal. We give necessary and sufficient conditions for the problem to have a solution, in terms of the nature of the two sets involved in the problem. Since the number of constraints can in general be different from the number of signal parameters, the problem can be exactly determined, underdetermined or overdetermined. We describe the solutions in each of these situations. The connection with oversampling and variational formulations is also discussed.</P>

Flexible and Transparent MoS₂ Field-Effect Transistors on Hexagonal Boron Nitride-Graphene Heterostructures

Lee, Gwan-Hyoung,Yu, Young-Jun,Cui, Xu,Petrone, Nicholas,Lee, Chul-Ho,Choi, Min Sup,Lee, Dae-Yeong,Lee, Changgu,Yoo, Won Jong,Watanabe, Kenji,Taniguchi, Takashi,Nuckolls, Colin,Kim, Philip,Hone, James American Chemical Society 2013 ACS NANO Vol.7 No.9

<P>Atomically thin forms of layered materials, such as conducting graphene, insulating hexagonal boron nitride (hBN), and semiconducting molybdenum disulfide (MoS<SUB>2</SUB>), have generated great interests recently due to the possibility of combining diverse atomic layers by mechanical “stacking” to create novel materials and devices. In this work, we demonstrate field-effect transistors (FETs) with MoS<SUB>2</SUB> channels, hBN dielectric, and graphene gate electrodes. These devices show field-effect mobilities of up to 45 cm<SUP>2</SUP>/Vs and operating gate voltage below 10 V, with greatly reduced hysteresis. Taking advantage of the mechanical strength and flexibility of these materials, we demonstrate integration onto a polymer substrate to create flexible and transparent FETs that show unchanged performance up to 1.5% strain. These heterostructure devices consisting of ultrathin two-dimensional (2D) materials open up a new route toward high-performance flexible and transparent electronics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-9/nn402954e/production/images/medium/nn-2013-02954e_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn402954e'>ACS Electronic Supporting Info</A></P>

Superoscillations With Optimum Energy Concentration

Lee, Dae Gwan,Ferreira, Paulo Jorge S. G. IEEE 2014 IEEE transactions on signal processing Vol.62 No.18

<P>Oscillations of a bandlimited signal at a rate faster than the bandlimit are called “superoscillations” and have applications e.g. in superresolution and superdirectivity. The synthesis of superoscillating signals is a numerically difficult problem. Minimum energy superoscillatory signals seem attractive for applications because (i) the minimum-energy solution is unique (ii) it has the smallest energy cost (iii) it may yield a signal of the smallest possible amplitude. On the negative side, superoscillating functions of minimum-energy depend heavily on cancellation and give rise to expressions that have very large coefficients. Furthermore, these coefficients have to be found by solving equations that are very ill-conditioned. Surprisingly, we show that by dropping the minimum energy requirement practicality can be gained rather than lost. We give a method of constructing superoscillating signals that leads to coefficients and condition numbers that are smaller by several orders of magnitude than the minimum-energy solution, yet yields energies close to the minimum. In contrast with the minimum-energy method, which builds superoscillations by linearly combining functions with an ill-conditioned Gram matrix, our method combines orthonormal functions, the Gram matrix of which is obviously the identity. Another feature of the method is that it yields the superoscillatory signal that maximises the energy concentration in a given set, which may or may not include the superoscillatory segment.</P>

조기위암의 근치적 치료로서의 내시경적 점막절제술

이대희,이동호,송인성,정현채,정운태,최규완,김우호,이준행,김정룡,윤정환,임영석,이국래,김병관,황진혁,정준오 대한소화기내시경학회 1996 Clinical Endoscopy Vol.16 No.6

The endoscopic mucosal resection(EMR) is proposed by some Japanese investigators as a curative therapy of early gastric cancer(EGC) because of its minimal invasiveness and excellent results. To evaluate the possible role of EMR as a curative treatment modality of EGC, we retrospectively analyzed l9 casea with EGC initially treated by EMR in Seoul National University Hospital from December 1993 and January 1996. 1) The histologic diagnosis prior to EMR was adenocarcinoma in 12 cases(63%) and adenomatous polyp in 7 cases(38%), which were confirmed as adenocarcinoma after EMR. 2) The histologic curative resection was done in 7 cases(37%). Two cases of them showed recurrence of the gastric cancer and were treated by radical surgery. The other five cases have been closely observed by regular endoscopic examination without recurrence for the maximal period of 1~3 months. 3) Histoiogically inadequate resection(positive cancer cell in resection margin, submucosal cancer infiltration, or no cancer tissue in resected specimen) was done in 12 cases(73%). But two surgically resected cimens of them have no residual cancer cells, and there was no cancer cells in the follow-up biopsy of the other two patients. There 4 cases were seemed to he examples of buring effect of EMR. 4) After excluding five depressed lesions greater than 1 cm is long diameter, nine lesions were curatively treated by EMR. So successful EMR rate for strictly indicated lesions wsa 64%. 5) There was no signifieant complication related to the procedure. We thnnk that endoscopic mucosal resection has a potential role as a curative treatment modality in a highly selected patient with darly gastric cancer.

시사프라이드의 대장내시경 전처치 용액의 감량 효과

이성호,김현수,박찬원,이현택,이홍석,조대현,박정호,심상군,김현서,권정훈,장재권,성인경 대한소화기내시경학회 2000 Clinical Endoscopy Vol.21 No.5

Background/Aims: Polyethylene glycol (PEG) electrolyte lavage solution is now commonly used for peroral colonic preparation. However, the need to ingest a large volume reduces patient acceptance and may limit compliance, thereby resulting in improper preparation. This study was designed to assess whether adding of magnesium oxide or cisapride to PEG solution decreased the volume of PEG solution required without compromising the quality of the preparation. Methods: One hundred thirty seven patients undergoing outpatient colonoscopy were randomly chosen to receive one of three preparations (Group A: 4 L PEG; Group B: 2 L PEG plus cisapride 20 mg; Group C: 2 L PEG plus magnesium oxide 2 g). Endoscopist was blinded as to the method of preparation and scored the degree of colonic preparation (1 to 4). Results: Mean scores of preparation in group A, B, and C were 2.85, 2.69, and 2.20, respectively (p=0.001). There were significant differences of the degree of preparation between group A and group C, between group B and group C, but not between group A and group B. Conclusions: Two liters of PEG plus cisapride induced equally effective colonic preparation compared to four liter PEG solution. This results show that the addition of cisapride to PEG solution can reduce volume of PEG solution during colonoscopy preparation.

Superoscillations of Prescribed Amplitude and Derivative

Dae Gwan Lee,Ferreira, Paulo Jorge S. G. IEEE 2014 IEEE transactions on signal processing Vol.62 No.13

<P>Superoscillations occur when a bandlimited signal oscillates at a rate higher than its maximum frequency. We show that it is possible to construct superoscillations by constraining not only the value of the signal but also that of its derivative. This allows a better control of the shape of the superoscillations. We find that for any given bandwidth, no matter how small, there exists a unique signal of minimum energy that satisfies any combination of amplitude and derivative constraints, on a sampling grid as fine as desired. We determine the energy of the signal, for any grid, regular or irregular. When the set of derivative constraints is empty the results reduce to minimum energy interpolation. In the absence of amplitude constraints, we obtain pure derivative-constrained extremals. The flexibility gained by having two different types of constraints makes it possible to design superoscillations based only on amplitudes, based only on derivatives, or based on both. In the last case, the amplitude and derivative sampling grids can be interleaved or aligned. We explore this flexibility to build superoscillations that cost less energy. Illustrating examples are given.</P>