• Applied Chemistry for Engineering
• /
• v.9 no.4
• /
• pp.569-573
• /
• 1998

A water soluble polymer, polycondensate of 1-butylamine and epichlorohydrin (PBE), was synthesized by condensation of 1-butylamine and epichlorohydrin. The characteristics of PBE were determined by IR spectroscopy, low angle light scattering measurement, and $\zeta$ potential measurement. Its interactions with colloidal bentonite particles in aqueous medium were also studied. The results of the studies are as follows : PBE is a cationic polyelectrolyte carrying tertiary ammonium ions on its backbone. The average molecular weight of PBE is found to be about 1,600. The adsorption of PBE on the colloidal bentonite particles are well described with Langmuir adsorption isotherm. As the amounts of PBE adsorbed on the bentonite particles increase, the $\zeta$ potential of the particles changes its sign from negative to positive. This inversion of charge confirms that PBE is cationic in nature. The adsorption of PBE onto the bentonite particles was found to occur through cation exchange reaction. It has been shown that PBE has flocculation effects on the colloidal suspension of bentonite. It has also enhanced effects of filtrability on the digested sludge.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.5
• /
• pp.811-816
• /
• 2006

The single layered magnetic thin films with anisotropic magnetoresistance behavior have advantage on micro integration due to their low cost in manufacturing. Although the conventional MCo (M=Cu, Ag) amorphous ribbons using a rapid solidification process have showed appropriate for magnetic property for bulk devices, they are not appropriate for micro-scale devices due to their brittleness. We prepared the thermal evaporated 100 nm-thick $Cu_{1-x}Co_x\;and\;Ag_{1-x}Co_x(x=0.1{\sim}0.7)$ films on silicon wafers and investigated the magnetic property of the as-depo films such as magnetization and magnetoresistance ratio. We confirmed that the maximum MR ratio of 1.4 and 2.6% at the external field of 0.5 Tesla in $CuCo_{30},\;AgCo_{40}$ films, respectively. Our result implies that AMR may be slightly less than those of the conventional CuCo and AgCo ribbons due to surface scattering, but their AMR ratio be enough for micro-scale application with easy integration compatibility for the process without surface oxidation.

• Parasites, Hosts and Diseases
• /
• v.25 no.1
• /
• pp.24-36
• /
• 1987

The effect of praziquantel on P. westermani exposed in vitro was observed by stereomicroscope, light microscope and scanning electron microscope. Following results were found. 1. The worms incubated in $0.01{\;}{\mu}g/ml$ praziquantel were moving after 26-hour incubation. However, all of them were immobilized immediately after incubation in solutions over $0.01{\;}{\mu}g/ml$ concentration. 2. All of the exposed worms showed severe vacuolization not only in tegument but in subtegument, intestine, ovary, testis, Mehlis' gland and excretory bladder. 3. Vacuoles in tegument burst out to form craters. As incubation time went on, tegumental structure was disintegrated severely. The worms exposed to praziquantel were observed to be immobilized and be vacuolized of all tissues. Disintegration of reproductive organs suggests that praziquantel have suppressive effect on egg production when the flukes are not killed. The drug effects were found more related with incubation time than with drug concentration.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5A
• /
• pp.421-431
• /
• 2009

This paper is the study on the verification of structural health monitoring (SHM) algorithm based on the ultrasonic guided wave. An active inspection system using Lamb wave (LW) for SHM was considered. The basic study about the application of this algorithm was performed for detecting the circular notch defect in steel plate. LW testing technique, pitch-catch method, was used for interpretation of circular notch defect with depth of 50% of plate thickness and 7 mm width. Damage characterization takes place by comparing $S_0$ mode sensor signals collected before and after the damage event. By subtracting the signals of both conditions from each other, a scatter signal is produced which can be used for damage localization. The continuous Gabor wavelet transform is used to attain the time between the arrivals of the scatter and sensor signals. A new practical damage monitoring algorithm, based on damage monitoring polygon and pitch-catch method, has been proposed and verified with good accuracy. The possible damage location can be estimated by the average on calculated location points and the damage extent by the standard deviation.

• Progress in Medical Physics
• /
• v.10 no.1
• /
• pp.41-46
• /
• 1999

There is necessity for making a smaller and more sensitive detector in small field sizes. This report assesses the suitability of metal-loaded thermoluminescent dosimeters for this purpose. Measurements were performed in the 6 MV photon and 6 MeV electron beams of a medical linear accelerator with LiF thermoluminescence dosimeters (TLD-100) embedded in solid water phantom. TLD-100 chips(surface area 3.2 $\times$ 3.2 $\textrm{mm}^2$) loaded with a metal plate(Tin or gold respectively) were used to enhance dose readings to TLD-100. Surface dose was measured for field size 10 $\times$ 10 $\textrm{cm}^2$ and 100 em SSD. Measurements have been made of the enhanced signal intensity and good linearity for absorbed dose with each metal. Using a 1 mm each metal on TLD-l00 in the beam increased the surface dose to 14% and 56% respectively for 6MV photon. In the case of 6 MeV electron, gold plate enhanced the TL response to 13%, but there is no difference for tin plate. The specific dose response of TLD-100 with thin metal plate increases with electron concentration of metal film, this is most likely due to increased electron scattered from the additional material with electron density higher than TLD-100. This emphasizes the role of TL dosimeters with metal as amplified dosimeters for therapeutic high energy x-ray beams. Due to the enhanced dose reading of TLD-100 with metal plate, it could be possible to develop smaller TL dosimeter with high sensitivity.

• The Journal of Engineering Geology
• /
• v.22 no.4
• /
• pp.459-466
• /
• 2012

A difficulty encountered in engineering seismic mapping is that reflection events from shallow discontinuities are commonly overlapped with coherent noise such as air wave, direct waves, head waves, and high-amplitude surface waves. Here, the radial trace transform, a simple geometric re-mapping of a trace gather (x-t domain) to another trace gather (v-t domain), is applied to investigate the rejection effect of coherent linear noises. Two different types of data sets were selected as a representative database: good-quality data for intermediate sounding (hundreds of meters) in a sedimentary basin and very noisy data for shallow (${\leq}50m$) mapping of the weathered zone and bedrock surface. Results obtained with cascaded application of the radial transform and low-cut filtering proved to be as good as, or better than, those produced using f-k filtering, and were especially effective for air wave and direct wave. This simple transform enables better understanding of the characteristics of various types of noise in the RT domain, and can be generally applied to overcoming diffractions and back-scatterings caused by joints, fractures, and faults commonly that are encountered in geotechnical problems.

• The Journal of Korean Society for Radiation Therapy
• /
• v.26 no.2
• /
• pp.265-272
• /
• 2014

Purpose : To reduce the radiation dose to the thyroid that is affected to scattered radiation, the shield was used. And we evaluated the shielding effect for the thyroid during whole brain radiation therapy. Materials and Methods : To measure the dose of the thyroid, 300cGy were delivered to the phantom using a linear accelerator(Clinac iX VARIAN, USA.)in the way of the 6MV X-ray in bilateral. To measure the entrance surface dose of the thyroid, five glass dosimeters were placed in the 10th slice's surface of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. In the same location, to measure the depth dose of the thyroid, five glass dosimeters were placed in the 10th slice by 2.5 cm depth of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. Results : Entrance surface dose of the thyroid were respectively 44.89 mGy at the unshield, 36.03 mGy at the bismuth shield, 31.03 mGy at the 0.5 mmPb shield and 23.21 mGy at a self-made 1.0 mmPb shield. In addition, the depth dose of the thyroid were respectively 36.10 mGy at the unshield, 34.52 mGy at the bismuth shield, 32.28 mGy at the 0.5 mmPb shield and 25.50 mGy at a self-made 1.0 mmPb shield. Conclusion : The thyroid was affected by the secondary scattering dose and leakage dose outside of the radiation field during whole brain radiation therapy. When using a shield in the thyroid, the depth dose of thyroid showed 11~30% reduction effect and the surface dose of thyroid showed 20~48% reduction effect. Therefore, by using the thyroid shield, it is considered to effectively protect the thyroid and can perform the treatment.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.184-184
• /
• 2016

플라즈마에 레이저 빛을 입사한 후 CCD 소자로 획득한 영상은 검고 밝은 픽셀로 이루어지며 이를 플라즈마 스펙클 패턴이라 정의한다. 그림 1은 $NH_3$ 플라즈마에서 획득한 스펙클 패턴을 보이고 있다 [1]. 광학에서 스펙클 패턴은 빛의 산란을 이용해 정의하고 있지만 최근의 연구에서 이 같은 정의가 잘 못되어졌음이 보고된 바 있다 [2]. 스펙클 패턴은 입사된 빛 물질과 빛 물질 에너지를 흡수하는 표면 플라즈몬 캐리어 (surface plasmon carriers-SPC)가 함께 공존하는 전자계 에너지 필드라고 정의된 바 있다 [2]. 플라즈마 스펙클 패턴은 진공이 SPC와 같은 음의 물질과 입자로 채워져 있다는 가정에 기초하고 있다 [1]. 새로이 정의된 스펙클 패턴은 전하가 없는 photon 모델과는 달리 빛이 양의 전하를 가지고 있다는 사실에 기초한 것이며, 이는 최근의 빛 물질 수집과 관련한 실험적 연구 [3], 빛 물질의 화학적 원소 분석 [4], 빛 물질의 양의 입자성 [5]에 근거를 두고 있다. 빛 물질은 그림 2 [6] 에서와 같이 물 방울을 태양 또는 레이저 빛에 노출시켜 용이하게 수집할 수 있다 [3-6]. 플라즈마 스펙클 패턴에서 픽셀합 분포함수 (pixel sum distribution function-PSDF)을 구할 수 있으며, PSDF에서 추출한 정보는 optical emission spectroscopy, langmuir probe로 수집한 데이터와 매우 유사한 경향성을 보였다 [1, 6]. 이는 스펙클 패턴이 플라즈마의 광학적 전기적 정보를 저장하고 있음을 의미한다. 본 발표에서는 새로운 플라즈마 진단 방식으로서의 스펙클 이미징 시스템, 동작원리, 물리적 기초, 그리고 응용사례 등을 살펴본다.

• Korean Chemical Engineering Research
• /
• v.49 no.3
• /
• pp.297-300
• /
• 2011

High energy proton irradiations were performed on graphene devices to increase the number of defects intentionally. Proton energy and fluence were 6 MeV and $5{\times}10^{15}\;cm^{-2}$, respectively. The defects in few layer graphene layer created by proton irradiations captured oxygen molecules that acted as p-type dopants. After the vacuum annealing, hole mobility was enhanced by the recovery of the defects and the desorption of the oxygen molecules. However, the drain current decreased after vacuum annealing due to the removal of the dopant molecules.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.5
• /
• pp.458-465
• /
• 2003

In this paper, we analyze the transient electromagnetic response from three-dimensional(3-D) dielectric bodies using a time-domain electric field integral equation formulation. The solution method in this paper is based on the Galerkin＇s method that involves separate spatial and temporal testing procedures. Triangular patch basis functions are used for spatial expansion and testing functions for arbitrarily shaped 3-D dielectric structures. The time-domain unknown coefficients of the equivalent electric and magnetic currents are approximated as an orthonormal basis function set that is derived from the Laguerre functions. These basis functions are also used as the temporal testing. Numerical results involving equivalent currents and far fields computed by the proposed method are presented.