• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.342-343
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• 2013

AlSb is a promising material for optical devices, particularly for high-frequency and nonlinear-optical applications. And AlSb offers significant potential for devices such as quantum-well lasers, laser diodes, and heterojunction bipolar transistors. In this work we study molecular beam epitaxy (MBE) growth of an unstrained AISb film on a GaAs substrate and identify the real-time monitoring capabilities of in situ spectroscopic ellipsometry (SE). The samples were fabricated on semi-insulating (0 0 1) GaAs substrates using MBE system. A rotating sample stage ensured uniform film growth. The substrate was first heated to $620^{\circ}C$ under As2 to remove surface oxides. A GaAs buffer layer approximately 200 nm- thick was then grown at $580^{\circ}C$. During the temperature changing process from $580^{\circ}C$ to $530^{\circ}C$, As2 flux is maintained with the shutter for Ga being closed and the reflection high-energy electron diffraction (RHEED) pattern remaining at ($2{\times}4$). Upon reaching the preset temperature of $530^{\circ}C$, As shutter was promptly closed with Sb shutter open, resulting in the change of RHEED pattern from ($2{\times}4$) to ($1{\times}3$). This was followed by the growth of AlSb while using a rotating-compensator SE with a charge-coupled-device (CCD) detector to obtain real-time SE spectra from 0.74 to 6.48 eV. Fig. 1 shows the real time measured SE spectra of AlSb on GaAs in growth process. In the Fig. 1 (a), a change of ellipsometric parameter ${\Delta}$ is observed. The ${\Delta}$ is the parameter which contains thickness information of the sample, and it changes in a periodic from 0 to 180o with growth. The significant change of ${\Delta}$ at~0.4 min means that the growth of AlSb on GaAs has been started. Fig. 1b shows the changes of dielectric function with time over the range 0.74~6.48 eV. These changes mean phase transition from pseudodielectric function of GaAs to AlSb at~0.44 min. Fig. 2 shows the observed RHEED patterns in the growth process. The observed RHEED pattern of GaAs is ($2{\times}4$), and the pattern changes into ($1{\times}3$) with starting the growth of AlSb. This means that the RHEED pattern is in agreement with the result of SE measurements. These data show the importance and sensitivity of SE for real-time monitoring for materials growth by MBE. We performed the real-time monitoring of AlSb growth by using SE measurements, and it is good agreement with the results of RHEED pattern. This fact proves the importance and the sensitivity of SE technique for the real-time monitoring of film growth by using ellipsometry. We believe that these results will be useful in a number of contexts including more accurate optical properties for high speed device engineering.

• Applied Microscopy
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• v.23 no.1
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• pp.35-55
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• 1993

cis-Dichlorodiammineplatinum (II) (cis-Platin), a metallic compound, has widely been used as an effective anticancer chemotherapeutic agent. The precise mechanism of action of this agent is still unknown, but it is postulated that cis-Platin may act on the cancer cell like bifunctional alkylating agents. Although this agent is very beneficial to the patients with cervical cancer, germinoma of testis, neuroblastoma and others, it may also damage to the normal cell so that many side effects; severe hemorrhagic enterocolitis, bone marrow depression, renal damage and liver damage will develope. This experiment has been undertaken to pursue the cytotoxic effects of the cis-Platin on the ultrastructures of the interalveolar septum in the mouse lung. A total of 55 healthy male mice of ICR strain were used as experimental animals and divided into 5 mice of normal control group and 50 mice of cis-Platin treated group. The mice of cis-Platin treated group were sacrificed by carotid exsanguination at 6, 12, 24 hours, 3 days and 7 days after intraperitoneal injection of 6.0 mg of cis-Platin ($Abiplatin^R$ Abic Co. Ltd.) per kg of mouse body weight. The specimen obtained from the lower lobe of left lung were sliced into $1mm^3$ and prefixed with 2% glutaraldehyde -2.5% paraformaldehyde solution prepared with Millonig's phosphatae buffer solution (pH 7.4) at $4^{\circ}C$ for 3-4 hours. After postfixation with 1% osmium tetroxide solution all specimens were embedded in Epon 812. Ultrathin sections about $600-800{\AA}$ in thickness were stained with uranyl acetate and lead citrate and observed with Hitachi-600 electron microscope. The results obtained were as follows: 1. Local swellings with increase of electron density and number of pinocytic vesicles in the cytoplasms of the type I pneumocyte and endothelial cell of the blood air barrier in interalveolar septum of cis-platin treated mice were observed. 2. Cisternae of rough endoplasmic reticulum were dilated and sacculated in association with detachment of membrane bound ribosomes of the type II pneumocyte in interalveolar septum of cis-Platin treated mice. 3. Swollon mitochondria with uneven electron density of their matrix were observed in the type II pneumocyte of interalveolar septum in the cis-Platin treated mice. 4. The lamellae of lammelar bodies in type II pneumocyte of interalveolar septum in cis-Platin treated mice were devoided or transformed into homogeneous electron dense material. It is consequently suggested that cis-Platin would induce the cellular edema of type I pneumocyte and endothelial cell, and degenerative changes of cytoplasmic organelles of the type II pneumocyte in the interalveolar septum of the mouse lung.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.4
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• pp.287-297
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• 2014

For several decades, many countries operating nuclear power plants have been studying the various disposal alternatives to dispose of the spent nuclear fuel or high-level radioactive waste safely. In this paper, as a direct disposal of spent nuclear fuels for deep geological disposal concept, the rod consolidation from spent fuel assembly for the disposal efficiency was considered and analyzed. To do this, a concept of spent fuel rod consolidation was described and the related concepts of disposal canister and disposal system were reviewed. With these concepts, several thermal analyses were carried out to determine whether the most important requirement of the temperature limit for a buffer material was satisfiedin designing an engineered barrier of a deep geological disposal system. Based on the results of thermal analyses, the deposition hole distance, disposal tunnel spacing and heat release area of a disposal canister were reviewed. And the unit disposal areas for each case were calculated and the disposal efficiencies were evaluated. This evaluation showed that the rod consolidation of spent nuclear fuel had no advantages in terms of disposal efficiency. In addition, the cooling time of spent nuclear fuels from nuclear power plant were reviewed. It showed that the disposal efficiency for the consolidated spent fuel rods could be improved in the case that cooling time was 70 years or more. But, the integrity of fuels and other conditions due to the longer term storage before disposal should be analyzed.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.49-54
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• 2014

Background: Hydrogels are a class of polymers that can absorb water or biological fluids and swell to several times their dry volume, dependent on changes in the external environment. In recent years, hydrogels and hydrogel nanocomposites have found a variety of biomedical applications, including drug delivery and cancer treatment. The incorporation of nanoparticulates into a hydrogel matrix can result in unique material characteristics such as enhanced mechanical properties, swelling response, and capability of remote controlled actuation. Materials and Methods: In this work, synthesis of hydrogel nanocomposites containing magnetic nanoparticles are studied. At first, magnetic nanoparticles ($Fe_3O_4$) with an average size 10 nm were prepared. At second approach, thermo and pH-sensitive poly (N-isopropylacrylamide -co-methacrylic acid-co-vinyl pyrrolidone) (NIPAAm-MAA-VP) were prepared. Swelling behavior of co-polymer was studied in buffer solutions with different pH values (pH=5.8, pH=7.4) at $37^{\circ}C$. Magnetic iron oxide nanoparticles ($Fe_3O_4$) and doxorubicin were incorporated into copolymer and drug loading was studied. The release of drug, carried out at different pH and temperatures. Finally, chemical composition, magnetic properties and morphology of doxorubicin-loaded magnetic hydrogel nanocomposites were analyzed by FT- IR, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM). Results: The results indicated that drug loading efficiency was increased by increasing the drug ratio to polymer. Doxorubicin was released more at $40^{\circ}C$ and in acidic pH compared to that $37^{\circ}C$ and basic pH. Conclusions: This study suggested that the poly (NIPAAm-MAA-VP) magnetic hydrogel nanocomposite could be an effective carrier for targeting drug delivery systems of anti-cancer drugs due to its temperature sensitive properties.

• Clinical and Experimental Pediatrics
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• v.46 no.6
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• pp.536-540
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• 2003

Purpose : Aspiration of foreign material into the lungs can cause acute or chronic pulmonary diseases. It is difficult to detect small amounts of aspiration due to the lack of safe, sensitive and specific diagnostic tests. Recently, in animal or human studies, it has been reported that immunochemistry for lactalbumin can be used to detect the minimal aspiration. So, the authors' investigation was designed to determine whether human milk phagocytized alveolar macrophages can be detected in human milk aspirated mice. Methods : Sixty four male mice, 6-8 weeks old and 30-40 gm weighing, were used for this study. About 0.05 mL of human milk or normal saline were given intranasally once per day for 1 day or 3 days. Under anesthesia with ketamine and xylazine, the trachea of each mouse was cannulated with an 18G Jelco needle and then, each mouse's lungs were lavaged three times with 0.5 mL of phosphate buffer solution at 2, 8, 24, and 48 hours after the last milk or normal saline instillation. Cells in bronchoalveolar lavage fluid were stained with Oil Red O and immunocytochemistry for alpha-lactalbumin. Results : Immunocytochemical reactivity for alpha-lactalbumin or lipid-laden alveolar macrophages were not observed in the normal saline aspirated groups. Immunocytochemical reactivity for alpha-lactalbumin were observed in the human milk aspirated groups. They showed a peak at 8 hours and decreased markedly at 24 hours but persisted even at 48 hours after aspiration. Immunocytochemical stain positive alveolar macrophages were noted similarly in number between single and multiple aspiration groups. Conclusion : These observations suggested that alveolar macrophages for lactalbumin could be more easily detected on immunocytochemistry than Oil Red O stain, and immunocytochemistry could be used as a sensitive and specific diagnostic test for the detection of human milk aspiration.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.86-94
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• 2012

In this paper we propose a hardware architecture of high-speed CGH (computer generated hologram) generation processor, which particularly reduces the number of memory access times to avoid the bottle-neck in the memory access operation. For this, we use three main schemes. The first is pixel-by-pixel calculation rather than light source-by-source calculation. The second is parallel calculation scheme extracted by modifying the previous recursive calculation scheme. The last one is a fully pipelined calculation scheme and exactly structured timing scheduling by adjusting the hardware. The proposed hardware is structured to calculate a row of a CGH in parallel and each hologram pixel in a row is calculated independently. It consists of input interface, initial parameter calculator, hologram pixel calculators, line buffer, and memory controller. The implemented hardware to calculate a row of a $1,920{\times}1,080$ CGH in parallel uses 168,960 LUTs, 153,944 registers, and 19,212 DSP blocks in an Altera FPGA environment. It can stably operate at 198MHz. Because of the three schemes, the time to access the external memory is reduced to about 1/20,000 of the previous ones at the same calculation speed.

• Tunnel and Underground Space
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• v.19 no.5
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• pp.373-387
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• 2009

Considering the current construction technology and research status of deep repository tunnels for radioactive waste disposal, it is inevitable to use cementitious materials in spite of serious concern about their long-term environmental stability. Thus, it is an emerging task to develop low pH cementitious materials. This study reviews the state of the technology on low pH cements developed in Sweden, Switzerland, France, and Japan as well as in Finland which is constructing a real deep repository site for high-level radioactive waste disposal. Considering the physical and chemical stability of bentonite which acts as a buffer material, a low pH cement limits to $pH{\leq}11$ and pozzolan-type admixtures are used to lower the pH of cement. To attain this pH requirement, silica fume, which is one of the most promising admixtures, should occupy at least 40 wt% of total dry materials in cement and the Ca/Si ratio should be maintained below 0.8 in cement. Additionally, selective super-plasticizer needs to be used because a high amount of water is demanded from the use of a large amount of silica fume.

• Journal of the Mineralogical Society of Korea
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• v.25 no.3
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• pp.155-162
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• 2012

We observed characteristic oxidation and dissolution phenomena induced by dissolved oxygen for mackinawite that is produced via sulfate-reducing bacteria (SRB) living in anaerobic environments such as soils and groundwater. We tried to recognize the role of the sulfide minerals that usually coexist with some stabilized radionuclides (e.g., reduced uranium), which can be reoxidized and redissolved by an oxygen-rich groundwater invaded into a contaminated area. The mackinawite produced by 'Desulfovibrio desulfuricans', a sulfate-reducing bacterium, was conducted to be dissolved for 2 weeks by some oxidants such as 'hydrogen peroxide' and 'sodium nitrite'. Although mineralogical oxidation and dissolution characteristics were different from each other according to the oxidants, the initially oxidized solution was early stabilized through the oxygen consumption by ${\mu}m$-sized sulfide particles and the resultant increase of sulfate in solution. From these results, we can anticipate that the large amount of sulfide minerals generated by SRB can not only repress the anoxic environment to be disturbed by the consumption of oxygen in groundwater, but also contribute to stabilize the reduced/precipitated radionuclides as a buffer material for a long time.

• Analytical Science and Technology
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• v.18 no.4
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• pp.271-277
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• 2005

Urea in blood has been measured as an effective marker for diagnosis of renal function. Urea which is e end-product of nitrogen containing metabolites such as proteins is filtered through glomeruli of kidneys and then excreted as urine. If the renal function is deteriorated, the urea concentration in blood will be increased, from which the healthiness of renal function is judged. In order to improve the confidence of diagnosis results, the results must keep traceability chain to certified reference materials, which was certified by primary reference method. In this study, we proposed isotope dilution-liquid chromatography/mass spectrometry (ID-LC/MS) as a candidate primary method, in which $15^N_2$-urea is used as an internal reference material. The developed method is highly accurate in principle and is convenient as it does not require cumbersome derivatization. 0.1 mmol/L ammonium chloride was selected as a mobile phase for HPLC because it provided low interference in MS analysis of relatively low molecular weighted urea. HPLC and MS were connected with an electrospray ionization (ESI) interface of positive mode, which provided high sensitivity and reproducibility. The developed method was validated with internationally recognized reference materials, and we have obtained satisfactory results in an international ring trial. The expanded uncertainty calculated according to ISO guide was 1.8% at 95% confidence interval. The developed method is being used as a primary reference measurement method such as for certification of serum certified reference materials (CRMs).

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.239-247
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• 2005

In this study, an experimental study on the sorption properties of uranium(VI) onto bentonite colloids generated from a domestic calcium bentonite (called as Gyeongju bentonite). Gyeongju bentonite has been considered as a potential candidate buffer material in the Korean disposal concept for high-level radioactive wastes. The size and concentration of the bentonite colloids used in the sorption experiment were measured by a filtration method. The result showed that the concentration of the synthesized bentonite colloid suspension was 5100ppm and the size of the most of bentonite colloids(over $98\%$) was in the range of 200-450nm in diameter. The amount of uranium lost by the sorption onto bottle walls, by precipitation, and by ultrafiltration or colloid formation was analyzed by carrying out some blank tests. The loss of uranium by the ultrafiltration was significant in the lower ionic strength(i.e., in the case of 0.001M $NaClO_4$) due to the cationic sorption effect onto the ultrafilter by a surface charge reversion. The distribution coefficient (or pseudo-colloid formation constant) for the sorption of uranium(VI) onto bentonite colloids was $10^4^{\sim}10^6$ mL/g depending upon pH and the distribution coefficient was highest in the neutral pH around 6.5.