• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.189-192
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• 2001

In this paper, an novel optical measuring system based on the electro-optic effect has been proposed and realized using Pockels cell with a view to detecting partial discharge taking place at the needle plane electrode. This system has the following advantages ; nonmetallic probe sensor, immune to external EMI noise and broad band response of the Pockels cell from DC to GHz. This system is constructed by He-Ne laser, Mach-Zehnder interferometer with Pockels sensor, balanced photo receiver, data acquisition board and PC. The response characteristics of the developed proto type sensor are examined for AC and corona discharge.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.475-483
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• 2007

This paper proposes a readout integrated circuit (ROIC) for $32{\times}32$ infrared focal plane array (IRFPA) detector, which consist of reference resistor, detector resistor, reset switch, integrated capacitor and operational amplifier. Proposed ROIC is designed using $0.35{\;}{\mu}m$ 2P-4M (double poly four metal) n-well CMOS process parameters. Low noise folded cascode operational amplifier which is a key element in the ROIC showed 12.8 MHz unity-gain bandwidth and open-gain 89 dB, phase margin $67^{\circ}$, SNR 82 dB. From proposed circuit, we gained output voltage variation ${\Delta}17{\};mV/^{\circ}C$ when the detector resistor varied according to the temperature.

• Journal of Digital Contents Society
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• v.5 no.4
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• pp.289-294
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• 2004

For the purpose of image analysis, we usually take the application method relying on the various mathematical theories. On the respect of image as two variable function one may uses the gradient vector or several type of energy functions induced by the conventional (partial) derivative. We also have used the tangent plane or curvature vector from the concept of differential geometry {**]. However, these mathematical tools my assume that the given function should be sufficiently smoothing enough to depict every local variation continuously. But the real application of these mathematical methods to the natural images or phenomena may occur the ill-posed problem. In this paper, we have defined the weak derivative as a loose form of the derivative so that it my applied to the irregular case with less ill-posed problem.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.2
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• pp.97-102
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• 2011

Purpose: IMRT QA using 2Dimensional array detector is carried out with condition for discrete dose distribution clinically. And it can affect uncertainty of evaluation using gamma method. We analyze gamma index variation according to grid size and suggest validate range of grid size for IMRT QA in Hospital. Materials and Methods: We performed QA using OniPro I'mRT system software version 1.7b on 10 patients (head and neck) for IMRT. The reference dose plane (grid size, 0.1 cm; location, [0, 0, 0]) from RTP was compared with the dose plane that has different grid size (0.1 cm, 0.5 cm, 1.0 cm, 2.0 cm, 4.0 cm) and different location (along Y-axis 0 cm, 0.2 cm, 0.5 cm, 1.0 cm). The gamma index variation was evaluated by observing the level of changes in Gamma pass rate, Average signal, Standard deviation for each case. Results: The average signal for each grid size showed difference levels of 0%, -0.19%, -0.04%, -0.46%, -8.32% and the standard deviation for each grid size showed difference levels of 0%, -0.30%, 1.24%, -0.70%, -7.99%. The gamma pass rate for each grid size showed difference levels of 0%, 0.27%, -1.43%, 5.32%, 5.60%. The gamma evaluation results according to distance in grid size range of 0.1 cm to 1.0 cm showed good agreement with reference condition (grid size 0.1 cm) within 1.5% and over 5% in case of the grid size was greater than 2.0 cm. Conclusion: We recognize that the grid size of gamma evaluation can make errors of IMRT QA. So we have to consider uncertainty of gamma evaluation according to the grid size and apply smaller than 2 cm grid size to reduce error and increase accuracy clinically.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.1
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• pp.27-37
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• 1994

To catch the relative importance of varietal and environmental variation in various grain quality components associated with palatability of cooked rice, grain appearance, milling recovery, several physicochemical properties of milled rice and texture or eating quality of cooked rice for rice materials of five japonica cultivars, produced at four locations of the mid-mountainous and alpine area of Korea in 1989, were evaluated and analyzed the obtained data. Highly significant varietal and locational variations were detected in 1000-grain weight, amylose content, K/Mg ratio, gelatinization temperature, peak viscosity, breakdown and setback viscosities as compared with variety x location interaction variation. Also, marked locational variations were recongnized in milling recovery from rough to brwon rice, alkali digestibility and protein content, and significant varietal variation was caught in stickiness /hardness ratio of cooked rice. The variety x location interaction variation was especially large in quality components of grain appearance and ripening, palatability of cooked rice and consistency viscosity. One thousand kernel weight was heaviest in Jinbuolbyeo and Odaebyeo, and the unfilled grain ratio was lowest in Jinbuolbyeo. Odaebyeo showed slightly' lower ratio of intact and clear milled rice because of more chalky rice kernels compared with other cultivars. Amylose content of Jinbuolbyeo and Sobaegbyeo was about 1% lower than that of others and K/Mg ratio of Odaebyeo was the lowest one among rice materials. Odaebyeo, Sobaegbyeo and Jinbuolbyeo revealed significantly low gelatinization temperature and setback viscosity while high peak and breakdown viscosities. Cholwon rice showed the greatest kernel weight, good grain filling but lowest ratio of intact and clear milled rice while Jinbu rices exhibited the highest milling recovery from rough to brown rice and ratio of sound milled rice. Amylose content of milled rice in Jinbu rices was about 2-3% lower than those in other locations. Protein content of polished rice was about 1% lower in rice materials of middle zone than those of southern part of Korea. K/Mg ratio of milled rice was highest in Jinbu rice and potassium content was slightly higher in the rice materials of middle region than in those of southern region. Alkali digestion value and gelatinization temperature of polished rice was markedly high in Jinbu rices as compared with other locations. Breakdown viscosity was hightest in Chlown rices and next higher with the order of Hwaso>Unbong>Jinbu rices, and setback viscosity was the quite contrary tendency with breakdown. The stickiness /hardness ratio of cooked rice was relatively higher value in Cholwon rices than in the others and the palatability of cooked rice was a little better in Unbong and Cholwon rices than in Jinbu and Hwaso rices, although variety x location interaction variation was large. The rice materials can be classified largely into two groups of Jinbu and the others by the distribution on the plane of 1st and 2nd principal components (about 60% of total informations) contracted from twelve grain quality properties closely associated with eating quality of cooked rice. Also, Jinbu and the other rices were divided into two and three rice groups respectively. Varietal variation of overall rice quality was smallest in Hwaso. The most superior rice group in overall quality evaluation included Odaebyeo produced at Cholwon, Unbong and Hwaso, and Sobaegbyeo grown at Unbong

• The korean journal of orthodontics
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• v.18 no.2
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• pp.459-474
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• 1988

A study was made of a method of rational assessment on the roentgeno-cephalogram in orthodontic practice. Fifty eight measurements were analyzed on the roentgeno-cephalograms of 50 male and 50 female Korean adults with the acceptable profile and the normal occlusion. The means and standard deviations of measurements were studied in male and female groups by various analytic methods, and the sex difference was examined statistically. The obtained data were compared with those of the Japanese and American standards by useing a Japanese adults standard polygon chart reported by lizuka and Ishikawa. Amongs of 58 measurements, 14 have been selected as statistically significant and clinically useful, and used to make a Korean adult standard polygon chart. The results obtained were as follows: 1. Standards for cphalometric analysis in Korean adults were obtained, and the polygon chart and cephalometric profilogram were also made by using the standards in order to apply to a clinical diagnosis. 2. The sex difference was recognized in linear measurements, but not in angular measurments. 3. In comparison with the American standards from Downs and Graber, the Korean showed significant differences in angle of convexity, mandibular plane angle, Y-axis angle, interincisal angle and lower incisor to mandibular plane angle. Thus, the Korean showed a more retruded chin position, convex facial type, than white people. 4. In comparison with the Japanese standards from Iizuka and Ishikawa, the Korean showed a significant similarity with the Japanese, especially in females. 5. Upper incisor to Huxely line angle, established as a new measurement, proved to be paralell to X-Y axis angle.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.5
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• pp.543-550
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• 2011

The gravity anomaly is a basic geophysical data applied in various fields such as geophysics, geodesy and national defense. In general, the gravity anomaly is used through a interpolation process based on the constructed database. The gravity variation, however, is appeared in various shapes depending on the topography and the density of the underground structures. Therefore, the interpolation could lead to a large differences if the gravity fields do not satisfy the assumptions on the signal behavior like linear or a certain degree polynomials. Furthermore, the interpolation does not reflect the physical characteristics of the gravity such as the harmonic condition. In this study, the gravity modeling using the plane Fourier series and radial basis functions are performed to overcome the problems in the usual interpolation. The results of the modeling is analyzed for the case of the gravity referenced navigation focused on the signal characteristics. Based on the study, it was found that the results from modeling are not much different to that from the interpolation in a smoothly varied area. In case of the highly varied area, however, a large differences are appeared among the three methods. Especially, the Fourier series shows the most smooth variations in the modeled gravity values while the highest variations appeared in the interpolation. Applying to the gravity referenced navigation, it was found that the modeling is more effective in calculation cost. It is considered that the results from this study provides a basis on effective modeling of the gravity fields in terms of the signal characteristics and resolution for various application fields.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.2
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• pp.15-22
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• 1991

When $YBa_2Cu_3Ox$ is liquid-phase sintered at $925^{\circ}C$ in $O_2$ for 16h, liquid pockets are entrapped within the grains. The liquid pockets show a thin parallelepiped shape with short edge lengths in the c axis, even after reannealing $925^{\circ}C$ in $O_2$ for 16h. All grains in contact with the liquid matrix show the same shape. However, when liquid-phase sintered at 925^{circ}C in $N_2$ for 16h, the grains dispersed in the liquid matrix show a thicker parallelepiped shape than in $O_2$, and their shape remains intact even after reannealing at $925^{\circ}C$ in $N_2$ for 16h. The effect of atmosphere on the grain shape is expected to be due to the variation of oxygen vacancy concentraion in $CuO_2$ plane of tetragonal unit cell.

• Geomechanics and Engineering
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• v.15 no.5
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• pp.1113-1124
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• 2018

Geological dynamic hazards during deep coal mining are caused by the failure of a composite system consisting of the rock and coal layers, whereas the joint in coal affects the stability of the composite system. In this paper, the compression test simulations for the rock-coal combined body with single joint in coal were conducted using $PFC^{2D}$ software and especially the effects of joint length and joint angle on strength and failure characteristics in a rock-coal combined body were analyzed. The joint length and joint angle exhibit a deterioration effect on the strength and affect the failure modes. The deterioration effect of joint length of L on the strength can be neglected with a tiny variation at ${\alpha}$ of $0^{\circ}$ or $90^{\circ}$ between the loading direction and joint direction. While, the deterioration effect of L on strength are relatively large at ${\alpha}$ between $30^{\circ}$ and $60^{\circ}$. And the peak stress and peak strain decrease with the increase of L. Additionally, the deterioration effect of ${\alpha}$ on the strength becomes larger with the increase of L. With the increase of ${\alpha}$, the peak stress and peak strain first decrease and then increase, presenting "V-shaped" curves. And the peak stress and peak strain at ${\alpha}$ of $45^{\circ}$ are the smallest. Moreover, the failure mainly occurs within the coal and no apparent failure is observed for rock. At ${\alpha}$ between $30^{\circ}$ and $60^{\circ}$, the secondary shear cracks generated in or close to the joint tips, cause the structural instability failure of the combined body. Therefore, their failure models present as a shear failure along partial joint plane direction and partially cutting across the coal body or a shear failure along the joint plane direction. However, at ${\alpha}$ of $60^{\circ}$ and L of 10 mm, the "V-shaped" shear cracks cutting across the coal body cause its final failure. While crack nucleations at ${\alpha}$ of $0^{\circ}$ or $90^{\circ}$ are randomly distributed in the coal, the failure mode shows a V-shaped shear failure cutting across the coal body.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.2
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• pp.55-63
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• 1998

Recently the modified mild-slope equation has been developed by several researchers using different approaches, which, compared to the Berkhoff's mild-slope equation, includes additional terms proportional to the square of bottom slope and to the bottom curvature. By examining this equation, it is shown that both terms are equally important in intermediate-depth water, but in shallow water the influence of the bottom curvature term diminishes while that of the bottom slope square term remains significant. In order to examine the importance of these terms in more detail, the modified mild-slope equation and the Berkhoff's mild-slope equation are tested for the problems of wave reflection from a plane slope, a non-plane slope, and periodic ripples. It is shown that, when only the bottom slope is concerned, the mild-slope equation can give accurate results up to a slope of 1 in 1 rather than 1 in 3, which, until now, has been known as the limiting bottom slope for its proper application. It is also shown that the bottom curvature term plays an important role in modeling wave propagation over a bottom topography with relatively mild variation, but, where the bottom slope is not small, the bottom slope square term should also be included for more accurate results.