• KSBB Journal
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• v.14 no.5
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• pp.585-592
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• 1999

This study was aimed to enhance the Fe(II) oxidation rate using immobilized cells of Thiobacillus ferroxidans. For this purpose, a medium for the minimization of jarosite formation was developed first. Secondly, cell immobilization in celite beads was carried out. And then, repeated-batch and continuous operatons of Fe(II) oxidation by using immobilization cells were performed. In a series of flask cultures, three types of media were tested: media with a much lower salt concentration than that of the 9K medium; media which contained different nitrogen sources from that of the 9K medium, that is $(NH_4)_2HPO_4$, $NH_4Cl and HNO$_3$; media which contained $(NH_4)_2HPO_4$ as nitrogen and phosphate source, but without $K_2HPO_4$ as nitrogen and phosphate source in the 9K medium. As a result, the M16 medium which contained 3 g/L of $(NH_4)_2HPO_4$ as nitrogen and phosphate source was found to be the optimal one. It sustained good cell growth allowing no jarosite formation. In the repeated-batch operations, the rate of Fe(II) oxidation gradually increased to reach a maximum value as the batch was repeated. As a result of repeated-batch operations. a maximum Fe(II) oxidation rate was 2.33 g/L . h. In the continuous operations, the iron oxidation rate could be increased to 2.14 g/L .h at a dilution rate of 0.25 $h^{-1}$ which is greater than the maximum specific growth rate (0.12 $h^{-1}$) of the bacteria.

• Analytical Science and Technology
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• v.10 no.4
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• pp.282-290
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• 1997

The sorption and desorption properties of U(VI), Th(IV), Zr(IV), Cu(II), Pb(II), Ni(II), Zn(II), Cd(II) and Mn(II) ions on XAD-16-[4-(2-thiazolylazo)orcinol] (TAO) chelating resin were studied by elution method. The effect was examined with respect to overall capacity of each metal ion, separation of mixed metal ions, flow rate and concentration of buffer solution for optimum condition of sorption. The overall capacities of some metal ions on this chelating resin were 0.35nmol U(VI)/g resin, 0.49nmol Th(IV)/g resin, 0.41nmol Cu(II)/g resin, and 0.31nmol Zr(IV)/g resin, respectively. The elution order of metal ions obtained from breakthrough capacity and overall capacity at pH 5.0 was Th(IV)>Cu(II)>U(VI)>Zr(IV)>Pb(II)>Ni(II)>Zn(II)>Mn(II)>Cd(II). The group separation of mixed metal ions was possible by increasing pH in pH range 2~5 at a flow rate of 0.28mL/min. Characteristics of desorption were investigated with desorption agents such as $HNO_3$, HCl, $HClO_4$, $H_2SO_4$, and $Na_2CO_3$. It was found that 2M $HNO_3$ showed high desorption efficiency to most of metal ions except Zr(IV) ion. Also, desorption and recovery of Zr(IV) ion were successfully performed with 1M $H_2SO_4$. Recovery of trace amount of U(VI) ion from artificial sea water was over 94%. The chelating resin, XAD-16-TAO was successfully applied to group separation of rare earth metal ions from U(VI) by using 2M $HNO_3$ as an eluent.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1385-1390
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• 2006

외국에서 ASM 모델의 BNR 적용 연구결과를 국내 하수에 적용하기에는 하수농도, 온도, 슬러지농도 등이 국내와는 달라 적용상 무리가 있다. 본 연구에서 BNR 시뮬레이션을 위한 입력 자료로 활용되는 인자들은 IAWPRC task group에서 제안하는 값들을 사용하되 국내 하수성상에서 필요로 하는 인자들은 직접 실험을 통하여 부분적으로 구해냄으로써 모델 시뮬레이션의 신뢰도를 높이고자 하였다. F/M비의 변화량과 1/SRT과의 관계로부터, 종속영양미생물 생산계수 $Y_H$값을 구한결과, 0.40mg VSS/mg COD였다. 이것을 ASM No.2d에 적용하기 위하여 mg cell COD formed/mg COD oxidized 단위로 환산한 결과 0.58을 나타냈다. H 하수처리장의 1차 침전지 하수를 이용하여 호기성상태에서 OUR Test를 통한 미생물에 의한 유기물 섭취시 산소섭취율 변화를 측정하였다. 호기성상태와 무산소상태에서 구한 쉽게 분해되는 용존성유기물(Ss)값을 비교해보면 각각 35.5mg/L와 39.9mg/L로 약간의 차이는 있으나 유사한 값을 보여주고 있다. 시뮬레이션을 위한 동력학적 계수 중 무산소 상태에서 종속영양미생물의 ${\mu}_{max,H}$는 $3.56d^{-1}$로 나타났고, 호기성상태에서는 구하면 ${\mu}_{max,H}$는 $4.2d^{-1}$로 산출되었다. 종속영양미생물의 사멸계수 $b_H$를 구하기 위한 실험에서 초기 OUR의 10%이내가 될 때까지 걸린 시간은 7일정도가 걸렸으며, 사멸률 $b_H$는 $0.043hr^{-1}$로 나타났다. 독립영양미생물의 최대비성장률 ${\mu}_{max,A}$는 최대암모니아 섭취률을 이용하여 구한 결과 $0.65d^{-1}$로 나타났다.EX>$60%{\sim}87%$가 수심 10m 이내에 분포하였고, 녹조강과 남조강이 우점하는 하절기에는 5m 이내에 주로 분포하였다. 취수탑 지점의 수심이 연중 $25{\sim}35m$를 유지하는 H호의 경우 간헐식 폭기장치를 가동하는 기간은 물론 그 외 기간에도 취수구의 심도를 표층 10m 이하로 유지 할 경우 전체 조류 유입량을 60% 이상 저감할 수 있을 것으로 조사되었다.심볼 및 색채 디자인 등의 작업이 수반되어야 하며, 이들을 고려한 인터넷용 GIS기본도를 신규 제작한다. 상습침수지구와 관련된 각종 GIS데이타와 각 기관이 보유하고 있는 공공정보 가운데 공간정보와 연계되어야 하는 자료를 인터넷 GIS를 이용하여 효율적으로 관리하기 위해서는 단계별 구축전략이 필요하다. 따라서 본 논문에서는 인터넷 GIS를 이용하여 상습침수구역관련 정보를 검색, 처리 및 분석할 수 있는 상습침수 구역 종합정보화 시스템을 구축토록 하였다.N, 항목에서 보 상류가 높게 나타났으나, 철거되지 않은 검전보나 안양대교보에 비해 그 차이가 크지 않은 것으로 나타났다.의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로, 반전거래전략을 활용하는 경우 주식투자기간은 24개월이하의 중단기가 적합함을 발견하였다. 이상의 행태적 측면과 투자성과측면의 실증결과를 통하여 한국주식시장에 있어서 시장수익률을 평균적으로 초과할 수 있는 거래전략은 존재하므로 이러한 전략을 개발 및 활용할 수 있으며, 특히, 한국주식시장에 적합한 거래전략은 반전거래전략이고, 이 전략의 유용성은 투자자가 설정한 투자기간보다 더욱 긴 분석기간의 주식가격정보에 의하여 최대한 발휘될 수 있음을 확인하였다.(M1), 무역적자의 폭, 산업의 생산

• Water for future
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• v.28 no.6
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• pp.147-158
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• 1995

The purpose of this study is to establish a method of estimating the daily urban water demand using statistical model. This method will be used for the development of the efficient management and operation of the water supply facilities. The data used were the daily urban water use, the population, the year lapse and the weather conditions such as temperature, precipitation, relative humidity, etc. Kwangju city was selected for the case study area. The raw data used in this study were rearranged either by month or by season for the purpose of analysis, and the statistical analysis was applied to the data to obtain the regression model. As a result, the multiple linear regression model was developed to estimate the daily urban water use based on the seather condition. The regression constant and the model coefficients were determined for each month of a year. The accuracy of the model was within 3% of average error and within 10% of maximum error. The developed model was found to be useful to the practical operation and management of the water supply facilities.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.1
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• pp.57-67
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• 2013

Purpose: Replacing the film which used to be used for checking the set-up of the patient and dosimetry during radiation therapy, more and more EPID equipped devices are in use at present. Accordingly, this article tried to evaluated the accuracy of the position check-up and the usefulness of dosimetry during the use of an electronic portal imaging device. Materials and Methods: On 50 materials acquired with the search of Korea Society Radiotherapeutic Technology, The Korean Society for Radiation Oncology, and Pubmed using "EPID", "Portal dosimetry", "Portal image", "Dose verification", "Quality control", "Cine mode", "Quality - assurance", and "In vivo dosimetry" as indexes, the usefulness of EPID was analyzed by classifying them as history of EPID and dosimetry, set-up verification and characteristics of EPID. Results: EPID is developed from the first generation of Liquid-filled ionization chamber, through the second generation of Camera-based fluoroscopy, and to the third generation of Amorphous-silicon EPID imaging modes can be divided into EPID mode, Cine mode and Integrated mode. When evaluating absolute dose accuracy of films and EPID, it was found that EPID showed within 1% and EDR2 film showed within 3% errors. It was confirmed that EPID is better in error measurement accuracy than film. When gamma analyzing the dose distribution of the base exposure plane which was calculated from therapy planning system, and planes calculated by EDR2 film and EPID, both film and EPID showed less than 2% of pixels which exceeded 1 at gamma values (r%>1) with in the thresholds such as 3%/3 mm and 2%/2 mm respectively. For the time needed for full course QA in IMRT to compare loads, EDR2 film recorded approximately 110 minutes, and EPID recorded approximately 55 minutes. Conclusion: EPID could easily replace conventional complicated and troublesome film and ionization chamber which used to be used for dosimetry and set-up verification, and it was proved to be very efficient and accurate dosimetry device in quality assurance of IMRT (intensity modulated radiation therapy). As cine mode imaging using EPID allows locating tumors in real-time without additional dose in lung and liver which are mobile according to movements of diaphragm and in rectal cancer patients who have unstable position, it may help to implement the most optimal radiotherapy for patients.

• Applied Biological Chemistry
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• v.36 no.4
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• pp.271-276
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• 1993

This study was carried out to prepare anchovy based powder for instant soup packed in tea bag which can be used handily as a extractives, and to determine the taste compounds of extractives of anchovy based powder for instant soup. The anchovy based powder for instant soup was made by adding of 72% in the redried anchovy, 14% in the sea tangle, 7% in the mushroom and 7% in the katsuobushi to the total mixtures. And the anchovy based powder for instant soup was packed in tea bag. The desirable extraction time are 5 min in package in tea bag with air permeability $100\;m^3/m^2/min$ and over 20 min in package in tea bag with air permeability $65\;m^3/m^2/min$, respectively. Judging from the result of extraction rate of total nitrogen, color and sensory evaluation in extractives of anchovy based powder for instant soup extracted by optimal extraction time, the quality in extractives of instant soup packed in tea bag with air permeability $100\;m^3/m^2/min$ was superior to those of instant soup unpacked in tea bag and of instant soup packed in tea bag of air permeability $65\;m^3/m^2/min$. The principal taste compounds of extractives of anchovy based powder for instant soup packed in tea bag with air permeability $100\;m^3/m^2/min$ were IMP (9.26 mg/100ml in 5% solution) and free amino acids (24.30 mg/100 ml in 5% solution) such as histidine, proline, lysine and taurine. Total creatinine, betaine and TMAO were seemed to act an auxiliary role in taste of extracives of anchovy based powder for instant soup packed in tea bag with air permeability $100\;m^3/m^2/min$.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.27-38
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• 2009

To investigate the feasibility of refuse derived fuels (RDFs) combined of sewage sludge and combustible wastes such as substitutive fuels instead of a stone coal, several different RDFs made with different mixtures of sewage sludge and combustible wastes were analyzed by various experiments. The combustion characteristics for the RDFs were investigated by analyzing fuel gases, and heating values were also measured by a bomb calorimeter. The fundamental properties such as moisture contents, ratios of combustible materials, amounts of ashes, heavy metals, ratios of each chemical elements and heating values were analyzed in accordance with mixing ratios of wt(%) for researching the characteristics of the RDFs. $RDF_{k-1}$ was made of mixing materials which were dried sewage sludge, food wastes and combustible wastes. $RDF_{k-2}$ was made of mixing materials which were peat-moss, tar and sewage sludge. Combustion experiments were carried out at the optimal conditions which were m=2 under air-fuel condition and $850^{\circ}C$. The retention times in the combustor were set at 5, 10 and 15minutes. 50 g of RDFs was put in the combustor for each experiments. The ranges for heating values of $RDF_{k-1}$ with different mixing ratios were from 6,900 kcal/kg to 8120 kcal/kg. The ranges for heating values of $RDF_{k-2}$ with different mixing ratios were from 4,014 kcal/kg to 8,050 kcal/kg. As a result of this study, the heating values, moisture contents, components of chemical elements and mixing ratios of the materials in RDFs had big effects on the efficiency of the combustion. In $RDF_{k-1}$, the higher amounts of combustible wastes in the mixtures, the higher heating values, concentrations of $C_xH_y$ and amounts of ashes were produced. In $RDF_{k-2}$, the higher tar amounts in the mixtures caused the higher heating values, amounts of ashes, concentrations of CO gas and CxHy.

• The Journal of Korean Society for Radiation Therapy
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• v.24 no.1
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• pp.31-37
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• 2012

Purpose: This study evaluated the usefulness of Helmet bolus device using Bolx-II, paraffin wax, solid thermoplastic material in total scalp irradiation. Materials and Methods: Using Rando phantom, we applied Bolx-II (Action Products, USA), paraffin wax (Densply, USA), solid thermoplastic material (Med-Tec, USA) on the whole scalp to make helmet bolus device. Computed tomography (GE, Ultra Light Speed16) images were acquired at 5 mm thickness. Then, we set up the optimum treatment plan and analyzed the variation in density of each bolus (Philips, Pinnacle). To evaluate the dose distribution, Dose-homogeneity index (DHI, $D_{90}/D_{10}$) and Conformity index (CI, $V_{95}/TV$) of Clinical Target Volume (CTV) using Dose-Volume Histogram (DVH) and $V_{20}$, $V_{30}$ of normal brain tissues. we assessed the efficiency of production process by measuring total time taken to produce. Thermoluminescent dosimeters (TLD) were used to verify the accuracy. Results: Density variation value of Bolx-II, paraffin wax, solid thermoplastic material turned out to be $0.952{\pm}0.13g/cm^3$, $0.842{\pm}0.17g/cm^3$, $0.908{\pm}0.24g/cm^3$, respectively. The DHI and CI of each helmet bolus device which used Bolx-II, paraffin wax, solid thermoplastic material were 0.89, 0.85, 0.77 and 0.86, 0.78, 0.74, respectively. The result of Bolx-II was the best. $V_{20}$ and $V_{30}$ of brain tissues were 11.50%, 10.80%, 10.07% and 7.62%, 7.40%, 7.31%, respectively. It took 30, 120, 90 minutes to produce. The measured TLD results were within ${\pm}7%$ of the planned values. Conclusion: The application of helmet bolus which used Bolx-II during total scalp irradiation not only improves homogeneity and conformity of Clinical Target Volume but also takes short time and the production method is simple. Thus, the helmet bolus which used Bolx-II is considered to be useful for the clinical trials.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.2
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• pp.113-122
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• 2007

Purpose: We proposed the method using dose-volume Histogram index to compare prospective plan trials in tomotherapy planning optimization. Materials and Methods: For 3 patients in cranial region, thorax and abdominal region, we acquired computed tomography images with PQ 5000 in each case. Then we delineated target structure and normal organ contour with pinnacle Ver 7.6c, after transferred each data to tomotherapy planning system (hi-art system Ver 2.0), we optimized 3 plan trials in each case that used differ from beam width, pitch, importance. We analyzed 3 plan trials in each region with isodose distribution, dose-volume histogram and dose statistics. Also we verified 3 plan trials with specialized DVH-indexes that is dose homogeneity index in target organ, conformity index around target structure and dose gradient index in non-target structures. Results: We compared with the similarity of results that the one is decide the best plan trial using isodose distribution, dose volume histogram and dose statistics, and the another is using DVH-indexes. They all decided the same plan trial to better result in each case. Conclusion: In some of case, it was appeared a little difference of results that used to DVH-index for comparison of plan trial in tomotherapy by special goal in it. But because DVH-index represented both dose distribution in target structure and high dose risk about normal tissue, it will be reasonable method for comparison of many plan trials before the tomotherapy treatments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.423-428
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• 1998

The effective extraction methods and chemical components of crude polysaccharides of ascidian tunics were investigated. Tow extraction conditions, autoclaving or enzyme treatment, were applied. The proximate composition of ascidian tunics was not much different between those dried in raw (containing pigments) and those acetone treated and dried (decolorized), showing $50\%$ of carbohydrate and $40\%$ of protein. It was possible to extract up to $10\%$ of crude polysaccharides from ascidian tunics regardless of the extraction methods, autoclaving or enzyme treatment. In case of the latter the extraction yield by neutrase was higher than that with alkalase (Novo co.) or mixture 2000 (Pacific chemical co.). The most effective enzyme concentration and extraction time appeared to be 24 hrs of extraction with $3\%$ neutrase. On the other hand, in autoclave treatment, 6 hrs extraction showed most desirable extraction yield, about $9.7\%$. The compositions of amino acid of decolorized ascidian tunic (acetone treated group) and the crude polysaccharide from the autoclaving (water solubles) or neutrase treatment (enzyme digestibles) were similar to each other. Histidine was the highest both in the neutrase and autoclave treatment group and the yield were $29.2\%,\;20.4\%$, respectively, followed by aspartic acid and glutamic acid. Among the minerals, the content of Ca was significantly high, followed by Mg and Na.