• Polymer(Korea)
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• v.38 no.4
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• pp.457-463
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• 2014

In this study, the changes in the chemical structure and the physical property of fluoropolymer films (PTFE, FEP, PFA, PVDF, and ETFE) induced by $Co^{60}$ gamma ray in air, $N_2$, and vacuum environments were investigated. FTIR spectra of the irradiated fluoropolymers indicate that the oxidation proceeded by the reaction of radicals generated by irradiation with oxygen in air. The changes in the heat of fusion and the degree of crystallinity of the irradiated fluoropolymers were investigated using DSC and the results indicate that the scission and crosslinking reactions of the irradiated fluoropolymers were largely influenced by the chemical structure. It was also found that the mechanical property of the irradiated fluoropolymer films under an air atmosphere was significantly decreased.

• 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.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.4044-4052
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• 1996

Planar images of OH and $O_{2}$ with tunable KrF excimer laser which has a) 0.5 $cm^{-1}$ / linewidth, b) 0.5 nm tuning range, c) 150 mJ pulse energy, and d) 20 ns pulse width are obtained to determine spatial distributions of OH and $O_{2}$ in premixed $C_{3}$H$_{8}$ /O$_{2}$ flame. The technique is based on planar laser induced pre-dissociative fluorescence(PLIPF) in which collisional quenching is almost avoided because of the fast pre-dissociation. Dispersed LIPF spectra of OH and $O_{2}$ are also measured in a flame in order to confirm the excitation of single vibronic state of OH and $O_{2}$, OH and $O_{2}$ are excited on the P$_{2}$(8) line of the $A^{2}$.SIGMA.$^{+}$(v'= 3)-X$^{2}$.PI.(v'||'||'&'||'||'quot;= 0) band and R(17) line of the Schumann-Runge band B$^{3}$.SIGMA.$_{u}$ $^{[-10]}$ (v'= 0)- X$^{3}$.SIGMA.$_{g}$ $^{[-10]}$ (v'||'||'&'||'||'quot;= 6), respectively. Dispersed OH and $O_{2}$ spectra show an excellent agreement with simulated spectrum and previous works done by other group respectively. It is confirmed that OH widely distributed around flame front area than $O_{2}$.

• Polymer(Korea)
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• v.35 no.1
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• pp.13-16
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• 2011

In this study, the hydrogels composed of polyvinylpyrrolidone (PVP), ${\kappa}$-carrageenan (${\kappa}C$), and 1,2-hexanediol (HD) were prepared by ${\gamma}$-ray irradiation. The radiation dose was 25 kGy and the concentration of ${\kappa}C$ was 3 wt%. The physical properties of the hydrogels were investigated as a function of the concentrations of PVP and HD. The gel content and the tensile strength increased with increasing PVP concentration due to the crosslinking between the pyrrolidone molecules and decreased with increasing HD concentration. The degree of swelling was inversely proportional to the gel content because the highly crosslinked hydrogels had a tighter structure, hence reducing their water absorption. The antibacterial tests indicated that the hydrogels containing HD had antibacterial activity.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.428-435
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• 1994

Properties of modified rice starches prepared in drum drying and extrusion were evaluated to use for effective utilization. Blue value was the lowest (p<0.05) for waxy rice starch and L value was decreased after modification of starches. Water solubility index was the highest for modified starches prepared in extrusion, while water absorption index was the highest for modified starches prepared in drum drying. Cold-Water-Solubility was the highest (p<0.05) for modified rice starch prepared in drum drying (RD). Consistency index of RD was drastically increased as shear rate increased and yield stress was the highest for RD. Results of Gel Permeation Chromatography showed that starch components were broken down into lower molecular weight materials and amylose are degraded by modification. Changes in the X-ray diffrectometry pattern indicated the transformation of granule into an amorphous state during modification and illustrated V-type.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.318-323
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• 2000

The intercalated compounds of alkylsulfonates into hydrated zinc were synthesized. From the high temperature powder X-ray diffraction (HTXRD), FT-IR, and molecular size, the temperature dependence of orientation for the intercalated alkylsulfonates were determined. In the temperatures range 1, alkylsulfonates were intercalated into hexa aqua zinc layer with the bilayer structure of $32.9^{\circ}$angle for ${Zn(H_2O_4]^{2+}[C_nH_{2n+1}SO_3]_2\;^-$. In the temperatures range 2, alkylsulfonates were intercalated into tetra aqua zinc layer with the bilayer structure of $55.2^{\circ}$angle for ${Zn(C_nH_{2n+1}SO_3)_2$. In the temperatures range 3, alkylsulfonates were directly bonded to zinc ion with the bilayer structure of $76.5^{\circ}$angle for ${Zn(C_nH_{2n+1}SO_3)_2$.

• Polymer(Korea)
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• v.37 no.4
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• pp.449-454
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• 2013

In this work, the effect of electroless Ni-plating of multi-walled carbon nanotubes (MWCNTs) on thermal conductivity and fracture toughness properties of MWCNTs/$Al_2O_3$/epoxy composites was investigated. The surface properties of the Ni-plated MWCNTs were determined by scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), and X-ray diffraction (XRD) analyses. Thermal conductivity was tested using a thermal conductivity measuring system. The fracture toughness of the composites was carried out through the critical stress intensity factor ($K_{IC}$) measurement. As a result, the electroless Ni-plated MWCNTs led to a significant change of surface characteristics of the MWCNTs. Thermal conductivity and fracture toughness of the MWCNTs/$Al_2O_3$/epoxy composites were greater than those of non-treated ones. These results were probably due to the improvement of intermolecular interaction between the Ni-MWCNTs and the matrix resins.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.15-21
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• 2017

WHO reported that millions of people die every year because of diseases induced from environmental pollution. In 2012, approximately 7 million people were killed due to air pollution. Major cause of such pollution includes toxin, chemical waste, radiation and air pollution. Therefore, the significance and interest to indoor air quality has been continuously increased. Especially, the interest in radon, the ARC group 1 carcinogen, is rapidly increasing, and banning the use of construction materials that release radon, repairing aged buildings, and developing ventilators. To reduce the level of radon gas was inflowed to indoors and outdoors, this study is to research and develop a radon gas absorption board using absorbents. The absorbents utilized to absorb the radon gas were porous diatomite, natural zeolite, 4A zeolite and 13X zeolite and employed bentonite and illite, montmorillonites with the property of exchanging anions. As the main binder, magnesium oxide was used, with a content of 25% magnesium chloride.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.261-270
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• 2019

The separation permeation characteristics of $N_2-O_2$ gas in air at cell membrane model of skin which irradiated by high energy electron(linac 6 MeV) were investigated. The cell membrane model of skin used in this experiment was a sulfonated polydimethyl siloxane(PDMS) non-porous membrane. The pressure range of $N_2$ and $O_2$ gas were appeared from $1kg_f/cm^2$ to $6kg_f/cm^2$. In this experiment(temperature $36.5^{\circ}C$), the permeation change of $N_2$ and $O_2$ gas in non-porous membrane by non-irradiation were found to be $1.19{\times}10^{-4}-2.43{\times}10^{-4}$, $1.72{\times}10^{-4}-2.6{\times}10^{-4}cm^3(STP)/cm^2{\cdot}sec{\cdot}cmHg$, respectively. That of $N_2$ and $O_2$ gas in non-porous membrane by irradiation were found to be $0.19{\times}10^{-4}-0.56{\times}10^{-4}$, $0.41{\times}10^{-4}-0.76{\times}10^{-4}cm^3(STP)/cm^2{\cdot}sec{\cdot}cmHg$, respectively. The irradiated membrane was significantly decreased about 4-10 times than membrane which was not irradiated. And ideal separation factor of $N_2$ and $O_2$ gas by non-irradiation was found to be from 1.32 to 0.42 and that of $N_2$ and $O_2$ gas by irradiation was found to be from 0.237 to 0.125. The irradiated membrane was significantly decreased about 4-5 times than membrane which was not irradiated. When the operation change(cut) and pressure ratio(Pr) by non-irradiation were about 0, One was increased to the oxygen enrichment and the other was decreased to the oxygen enrichment. The irradiated membrane was significantly decreased about 4-19 times than membrane which was not irradiated. As the pressure of $N_2$ and $O_2$ gas was increased, the selectivity was decreased. As separation permeation characteristics of $N_2-O_2$ gas in cell membrane model of skin were abnormal, cell damages were appeared at cell.

• The Journal of the Acoustical Society of Korea
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• v.23 no.1
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• pp.1-7
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• 2004

We developed SH-SAW sensors to detect protein molecules in liquid solutions applying a particular antibody thin film on the delay line of transverse SAW devices. The antibody investigated was human-immune-globulin G (HigG) to hold the antigens (anti-HigG) in the protein solution. We fabricated the sensor generating 100 MHz with the piezoelectric single crystal LiTaO₃. We measured the frequency change of the sensor by adding the anti-body concentration on SAM (self assembled monolayer) deposited on the Au layer. The sensor showed stable response to the mass loading effects of the anti-HigG molecules with the sensitivity up to 10.8 ng/ml/Hz at noise level 400 Hz below.