• Journal of the Korean GEO-environmental Society
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• v.3 no.3
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• pp.53-63
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• 2002

Until recently the other attempts except linear elastic analysis using assumed elastic modulus had not been made in order to evaluate the settlement of the rock fill materials in Korea. Especially, it was almost impossible to predict the precise settlement of the breakwater structure made with dumped rubble stone. In this study, 3 sets of large scaled triaxial compression tests for porous basaltic quarry rocks were carried out and numerical simulation of those triaxial compression tests were performed applying non linear elastic model. Two stress-strain behaviors were compared to study the adaptability of hyperbolic constitutive model for the rubble stone. The results showed quite good agreements between the two stress-strain behaviors. Thus, the hyperbolic constitutive model is thought to be alternative approach evaluate the settlements of the loose rock-fill material.

• School Mathematics
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• v.15 no.4
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• pp.995-1013
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• 2013

The purpose of this paper was to investigate mathematics teachers' mathematical content knowledge about quadratic curves. Three components of mathematical knowledge are needed for teaching: (i) knowing school mathematics, (ii) knowing process of school mathematics, (iii) making connections between school mathematics and advanced mathematics. 24 mathematics teachers were asked to perform 10 questions based on mathematics curriculum. The results showed that mathematics teachers had some difficulties in conic section definitions and eccentricity definitions of ellipse and hyperbola. And they also got difficulty in Dandellin sphere proof of the equivalence of conic section definitions and quadratic curve definitions. Especially, no one answered correctly to the question about the definition of eccentricity. The ratio of correct answer for the question about constructing tangent lines of quadratic curves is less than that for the question about the applications of the properties of tangent lines. These findings suggests that it is needed that to provide plenty of opportunities to learn mathematical content knowledge in teacher education programs.

• Journal of Yeungnam Medical Science
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• v.15 no.2
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• pp.195-207
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• 1998

폐암을 집단 검진으로 조기 진단하려는 노력은 현재까지 뚜렷한 성과를 얻지 못하고 있는 실정이다. 미국의 국립암연구소에서 실시한 흉부엑스선 촬영과 객담세포진 검사를 이용한 폐암의 집단 검진 결과는 검진군에서 대조군보다 유의하게 진단율이 높았으며 절제율도 더 높았고 5년 생존율도 향상시킬 수 있었다. 그러나 폐암을 조기 진단하기 위한 집단 검진의 궁극적인 목표인 사망률을 감소시키지는 못하였다. 최근에는 미국 국립암 연구기관에서 실시했던 결과에 대한 해석이 다양하여 아직까지도 폐암 조기 진단에 있어서 흉부액스선촬영과 객담세포진검사의 의의에 관한 결론에 대해서는 논란이 되고 있다. 1993년부터 새로운 집단 검진에 관한 연구가 진행중에 있어서 그 결과가 나올 때까지는 흉부엑스선촬영과 객담세포진검사를 이용한 집단 검진의 의의에 대한 결과는 기다려 보아야 할 것이다. 분자생물학적으로 폐암을 조기 검진하기 위한 검체로는 혈액보다는 객담이 훨씬 적절하고 합리적인 검체이다. 폐암의 발생은 가장 먼저 기관지 상피 세포에서 일어나서 암화 과정의 여러 단계에서 다양한 종양 표지자가 객담에 섞여 나오기 때문에 이 표지자를 객담에서 측정하는 것이 훨씬 합리적인 조기 진단법이 될 수 있다. 동시에 폐암을 집단 검진으로 조기 진단하기 위해서는 종양 표지자를 대량으로 측정하기 위한 자동측정법도 개발되어야 할 것이다. 암을 예방하기 위하여는 여러면에서 방안이 연구되어야 한다. 즉 암발생의 가능성이 높은 대상을 선태하여야 하며 초기에 집단 검진으로 진단을 할 수 있어야 하고, 이러한 검진으로 추적 검사가 가능하여야 하며 마지막으로 결과를 판정할 수 있어야 한다. 이 가운데 현재까지 유일하게 실시할 수 없는 것은 조기 진단으로 사용할 수 있는 뚜렷한 종양 표지자가 없는 것이다. 이와 같이 현재까지는 폐암을 조기 진단하기 위한 특이한 표지자는 없으나 앞으로 폐암 발생 기전의 여러 단계가 체계적으로 밝혀진다면 그 과정에서 중요한 표지자들이 밝혀질 것이다. 그리고 이들을 간단하게 검사할 수 있는 검사법도 밝혀져 폐암 조기 진단의 궁극적 목적인 폐암으로 인한 사망률을 감소시킬 수 있을 것으로 기대된다.

• Progress in Medical Physics
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• v.10 no.1
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• pp.1-7
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• 1999

In this study, the dose distributions of a $^{32}$ p uniform cylindrical volume source and a surface source, a pure $\beta$emitter, were calculated in order to obtain information relevant to the utilization of a balloon catheter and a radioactive stent. The dose distributions of $^{32}$ p were calculated by means of the EGS4 code system. The sources are considered to be distributed uniformly in the volume and on the surface in the form of a cylinder with a radius of 1.5 mm and length of 20 mm. The energy of $\beta$particles emitted is chosen at random in the $\beta$ energy spectrum evaluated by the solution of the Dirac equation for the Coulomb potential. Liquid water is used to simulate the particle transport in the human body. The dose rates in a target at a 0.5mm radial distance from the surface of cylindrical volume and surface source are 12.133 cGy/s per GBq (0.449 cGy/s per mCi, uncertainty: 1.51%) and 24.732 cGy/s per GBq (0.915 cGy/s per mCi, uncertainty: 1.01%), respectively. The dose rates in the two sources decrease with distance in both radial and axial direction. On the basis of the above results, the determined initial activities were 29.69 mCi and 1.2278 $\mu$Ci for the balloon catheter and the radioactive stent using $^{32}$ P isotope, respectively. The total absorbed dose for optimal therapeutic regimen is considered to be 20 Gy and the treatment time in the case of the balloon catheter is less than 3 min. Absorbed doses in targets placed in a radial direction for the two sources were also calculated when it expressed initial activity in a 1 mCi/ml volume activity density for the cylindrical volume source and a 0.1 mCi/cm$^2$ area activity density for the surface source. The absorbed dose distribution around the $^{32}$ P cylindrical source with different size can be easily calculated using our results when the volume activity density and area activity density for the source are known.

• Journal of Broadcast Engineering
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• v.1 no.2
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• pp.118-132
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• 1996

This paper proposes a wavelet transform- based image compression method using the energy distribution. The proposed method Involves two steps. First, we use a wavelet transform for the subband decomposition. The original image Is decomposed into one low resolution subimage and three high frequency subimages. Each high frequency subimages have horizontal, vertical, and diagonal directional edges. The wavelet transform is luther applied to these high frequency subimages. Resultant transformed subimages have different energy distributions corresponding to different orientation of the high pass filter. Second, for higer compression ratio and computational effciency, we discard some subimages with small energy. The remaining subimages are encoded using either DPCM or quantization followed by entropy coding. Experimental results show that the proposed coding scheme has better performance in the peak signal to noise ratio(PSNR) and higher compression ratio than conventional image coding method using the wavelet transform followed by the straightforward vector quantization.

• Journal of the Korea Society of Computer and Information
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• v.15 no.10
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• pp.35-47
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• 2010

To complement inaccurate edge information and detect correctly the boundary of a vehicle in an image, an extended edge analysis technique is presented in this paper. The vehicle is detected using the bottom boundary generated by a vehicle and the road surface and the left and right side boundaries of the vehicle. The proposed extended edge analysis method extracts the horizontal edge by merging or dividing the nearby edges inside the region of interest set beforehand because various noises deteriorates the horizontal edge which can be a bottom boundary. The horizontal edge is considered as the bottom boundary and the vertical edges as the side boundaries of a vehicle if the extracted horizontal edge intersects with two vertical edges which satisfy the vehicle width condition at the height of the horizontal edge. This proposed algorithm is more efficient than the other existing methods when the road surface is complex. It is proved by the experiments executed on the roads having various backgrounds.

• Journal of Radiation Protection and Research
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• v.32 no.1
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• pp.21-26
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• 2007

This study is performed to evaluate the dose rate and to analyze the dose distribution of the gamma irradiation facility (IR-221) by using a Monte Calro simulation, which is helpful of upgrading the radiation processing qualification. Monte Cairo simulation is performed by MCNP4B code. Dose rates were measured at total 369 points with alanine dosimeters to compare the calculation results and the measurements data. The results have shown that the MCNP4B code is very useful to determine the dose distribution of the IR-221 gamma irradiation facility, as the calculation dose rate is within about ${\pm}5%$ of the measurement data. Dosimetry about the gamma irradiation facility usually needs enormous manpower and time. However Monte Cairo calculation method can reduce the tedious dosimetry jobs and improve the irradiation processing qualification, which will probably contribute to obtain the reliability of the irradiation products.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.146-151
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• 2017

This paper proposes a transmission algorithm that optimizes transmission power and sub-channel allocation to maximize energy efficiency considering characteristics of the channel impedance of power lines in power line communication systems. Since the received power at the receiver is influenced by the characteristics of the power line channel, it is necessary to consider channel characteristics when developing a transmission strategy in a power line communication systems. In addition, the energy efficiency should be optimized while meeting the practical constraints, such as the maximum transmission power limit of the transmitter and minimum quality of service for each user. In the computer simulation, we confirm that the energy efficiency of the proposed algorithm is improved compared to baseline schemes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.573-576
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• 2012

We have analyzed the induction effects by separation distance between the power feeding station and the telecommunication cables. To do this we measured the induced voltage in 11 sections(10km) between Jangseong and Imgok at Jeon-nam province using telecommunication cable installed nearby KTX's feeder line. Sub-section has about 1km length of telecommunication cable. And we used normalization method in installed length of telecommunication cables and mutual inductance to analysis the induction effects more rationally.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.961-963
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• 2015

In this study, we studied the effect of $Co^{60}$ gamma-radiation on the fiber Bragg gratings written by femtosecond UV laser in single mode optical fibers. The fiber Bragg gratings were exposed to gamma-radiation up to a dose of about 31.6 kGy at the dose rate of 106 Gy/min. According to the experimental data and analysis results, we confirmed Bragg gratings written by femtosecond laser have the excellent radiation-hardened characteristics for high radiation environments.