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정모 두부방사선규격사진 분석 시 기준선 설정 방법에 관한 비교 연구
김관모,황현식 전남대학교 치과대학 2001 구강과학 Vol.13 No.2
The purpose of this study was to find out the rationable of the construction of the reference lines using pupil position in the posteroanterior cephalometry. The PA cephalograms were taken in the forty adult subjects who had facial symmetry and normal occlusion, using pupil position market(PP market). Two weeks later, another PA cephalograms were obtained in the twenty subjects, using the same method to evaluate the reproducibility of pupil position by PP market. Two tracings were obtained from each PA cephalogram according to the method of the construction of reference line. One tracing was drawn with the horizontal reference line constructed by the line through right and left latero orbitake, and with the vertical reference line constructed by the line through crista galli and anterior nasal spine; Other tracing was drawn with the horizontal referencen line constructed by the line through right and left pupils, positional differences of vertical and horizontal reference line constructed by each method were compared by angle. Six pairs of anatomic landmarks were selected and their position differences between right and left sides were measured. Horizontal and vertical differences were compared between two methods. Following results were obtained. 1. The difference of pupil position on PA cephalogram which was taken by sing PP market was 0.37 mm horizontally and 0.38 mm vertically. 2. The difference of the horizontal line between the two methods was rather big (1.04±0.71˚) whereas the difference of vertical line was small(0.71±0.62˚). 3. In the comparison of the horizontal difference of the landmarks between right and left sides, the values of difference in the pupil position was smaller than in the anatomic landmark method; however the differences were not statistically significant. 4. The comparison of the vertical difference showed the same pattern with the horizontal difference, and further the difference was statistically significant in one landmark. The above results suggest that the PP marker may be helpful for construction of the reference line in the PA cephalometric radiography.
고태조,정병묵,양현모,박종권 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-
High precision machining technology has become one of the important parts in the development of a precision machine. Such a machine requires high speed on a large workspace as well as high precision positioning. For machining systems having a long stroke with ultra precision, a micro stage system with lever mechanism is proposed in this paper. The proposed micro stages are activated by the piezo-actuators with high precision, however, they have severe disadvantage for the travel range that the stroke is limited to a few microns. Because it is not easy to increase the stroke of piezo-actuator, it is very difficult to make an X-Y stage with only piezo-actuators. Therefore, in order to increase it, this paper proposes a lever mechanism for the piezo-actuator stage. In the experiments, we can confirm that the stroke is increased more than three times and it is possible to implement the micro X-Y stage using piezo-actuators.
Location Value and Price Leadership in a Product Differentiation Model
Hyeon-Mo Ku,Sang-Ho Lee 한국경영과학회 2007 Management Science and Financial Engineering Vol.13 No.2
This paper considers the value of location in a linear city model and examines the product differentiation equilibrium of duopoly providing different benefits to consumers. We show that if the value of location is small, symmetric location equilibrium occurs where two firms follow the maximal differentiation principle. However, as the value of location increases, asymmetric location equilibrium occurs where the low-value-location firm moves to the high-value-location firm and thus adjusted maximal differentiation principle holds. We also investigate two different price leadership model and demonstrate the relationship between the value of location and the role of price leadership. In particular, we show that when the location value is high, the price leadership by high-value-location firm will appear as a unique equilibrium.
Reactivities of chlorotrisylsilylenoid with ketones
Cho, Hyeon Mo,Lim, Young Mook,Lee, Myong Euy Royal Society of Chemistry 2010 Dalton Transactions Vol.39 No.39
<P>Chlorotrisylsilylenoid 1 reacted with both acetophenone and benzil to give the corresponding 2,5-dioxasilolanes and silylethers, respectively.</P> <P>Graphic Abstract</P><P>The reactions of a stable chlorotrisylsilylenoid with acetophenone and benzil were carried out to afford 2,5-dioxasilolane and silylether compounds. This result will provide a new synthetic route for functional silaheterocycles. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0dt00147c'> </P>