• Journal of Korean Society of Forest Science
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• v.48 no.1
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• pp.40-50
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• 1980

This research was carried out to examine the substitutional feasibility of low-priced materials produced in waste of forest instead of wheat flour which is extended for plywood adhesives. Wheat, pine bark, wood flour and pine foliage of coniferous trees or poplar foliage of hardwood species were selected and pulverized into 60-100 mesh minute powder after they were dried at $100-105^{\circ}C$ during 24 hours in the drying oven. The prepared particles as above were added to urea formaldehyde resin, urea-melamine copolymer resin and water soluble phenol formaldehyde resin in the ratio of 10, 20, 30 and 50%. After plywoods were processed by the above extending ratios, shear strength of extended plywoods were analyzed and discussed. The results obtained at this study were summarised as follows; 1. In the case of urea formaldehyde resin, both dry and wet shear strength of plywoods extended by wheat flour were shown the highest value. 2. Dry shear strength of urea-melamine copolymer resin was better than that of urea formaldehyde resin on the whole, while plywoods extended by wheat flour were shown excellent results. 3. Among 10% and 20% extensions of urea-melamine copolymer resin, the best results were shown by poplar leaves powder, wheat powder and wood flour. They had no significant difference statistically. 4. In the case of water soluble phenol formaldehyde resin, although dry shear strength of pine leaves powder was higher than that of wheat flour in the ratio of 10%, there was no significant difference between them in the ratio of 10 and 20%. 5. Among 20, 30 and 50% extensions of water soluble phenol formaldehyde resin, wet shear strength of wood flour and bark powder was higher than that of wheat flour. Wet shear strength of wood flour in the ratio of 10% was shown the same tendency as above.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.920-926
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• 2010

Marine alga, Chlorella vulgaris, was extracted by chloroform-methanol (2:1, v/v) solvents for lipid extraction at $35^{\circ}C$ for five hours (HCM-35) and its process was compared with conventional lipid extraction condition such as chloroform-methanol (2:1, v/v) at $65^{\circ}C$ for one hour (CM-65). This low temperature extraction process showed that 80% of total lipid was extracted and its residues contained relatively unchanged amounts of intact proteins and other minerals as well as amino acid profiles. Interestingly enough, the weight fraction of carbohydrate in the residues slightly increased due to less denaturation at low process temperature. The biological activities of the residues such as cytotoxicity and immune cell growth activation were not much changed after being extracted. The sensory evaluation were found to be very favorable for being used as a food additive and/or food supplement. This result could also help to maintain the economic feasibility of utilizing marine resources in food and other relevant industries.

• Journal of Chest Surgery
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• v.37 no.9
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• pp.742-748
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• 2004

The On-X valve was recently introduced. It was the aim of this study to assess the safety and feasibility from the data derived from 28 patients who underwent aortic and/or mitral valve replacement with this prosthesis in National Medical Center. Material and Method： From May 1999 and May 2003, a series of 28 consecutive patients who had been implanted with 32 On-X prosthesis were reviewed, The operative procedure comprised of 12 MVR, 10 AVR and 6 DVR. The study followed the guidelines of AATS/STS. Mean follow-up was 27 months (total 04 patient-years). Result: Early ($\leq$30 days) mortality was 7.44% (2/28) and no late mortality occurred in the study. Total actuarial freedom from mortality at 2 years was 92.86$\pm$4.87% for all cases, 100% for MVR, 90$\pm$9.49% for AVR, and 83.3$\pm$1.52% for DVR. Thromboembolic event occurred in 2 MVR patients and that was the only complication; therefore, the linearized incidence of valve related complications was 3.17%/ patient-years for all cases and 6.5%/patient-years for MVR and the actuarial freedom from valve related complications at 2 years was 84.85$\pm$10.75%. Preoperatively, 24 (85.71%) patients were in NYHA functional class III or IV but postoperatively, 25 (89,29%) patients were in NYHA functional class I or II. The levels of hemoglobin, hematocrit, serum LDH, reticulocyte rate and indirect bilirubin were all within normal range at postoperative 3 month. In mitral position, the peak gradient was 6.1$\pm$1.8 mmHg and the mean gradient was 3.0$\pm$0.6 mmHg and EOA were 2.54$\pm$0.56 $m^2$, 2.39$\pm$0.73 $m^2$, 2.34$\pm$0.55 $m^2$, 2.40$\pm$0.63 $m^2$ at 27 mm, 29 mm, 31 mm, 33 mm respectively. In aortic postion, the peak gradient was 21.1 $\pm$14.12 mmHg and the mean gradient was 12.3$\pm$6.52 mmHg. Conclusion: Since there was no significant difference in the postoperative mortality, valve related complications and echocardiographic hemodynamic data compared to standard bileaflet design and since there was an improvement in the NYHA functional class and normal values of hemolytic indicators, it can be assumed that On-X valve is safe and feasible. However, accumulation of cases and long-term follow-up of this patient group is needed to establish this result.

• Journal of Mushroom
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• v.12 no.3
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• pp.220-225
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• 2014

This study was conducted to set the proper sterilization standards of casing soil for the stable production of button mushroom(Agaricus bisporus) from mushroom disease that occurs in infection of casing soil material. Changes of aerobic bacteria are increased as the longer grow-out period and sharply increased after second flushes. Fluorescence Psuedomonas showed high density at high sterilization temperature and $100^{\circ}C$ treatment has extremely high density at 30 min and 60 min in casing 22 days. Density of thermophilic actinomyces is sharply increase from casing with soil and the highest density at 22 days of casing and rapidly decrease after first flushes. Sterilizing temperature of casing soil affects quality and quantity of button mushroom. Treatment of 60 min, 90 min at $80^{\circ}C$ and 30 min at $100^{\circ}C$ produced the highest mushroom yields, especially mushrooms yields of A grads were the highest at treatment of 90 min at $80^{\circ}C$. Treatment of 60min at $100^{\circ}C$ products many yields, however, this treatment has low economic feasibility for its yields. Sterilizing temperature of casing soil has an effect on generating diseases and insect pests. Treatment of 60 min, 90 min at $80^{\circ}C$ and 30 min $100^{\circ}C$ showed lower incidence than the other treatment. Although treatment of 30 min at $100^{\circ}C$ causes low diseases and mushroom fly damage, it has low mushroom yields. Furthermore, although treatment of 60 min at $100^{\circ}C$ has high mushroom yields, it causes high diseases and mushroom fly damage. Therefore the best conditions for the sterilization of casing soils was 60 min and 90 min at $80^{\circ}C$.

• The Korean Journal of Nuclear Medicine
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• v.33 no.3
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• pp.316-326
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• 1999

Purpose: We evaluated the feasibility of extracting pure left ventricular blood pool and myocardial time-activity curves (TACs) and of generating factor images from human dynamic N-13 ammonia PET using factor analysis. The myocardial blood flow (MBF) estimates obtained with factor analysis were compared with those obtained with the user drawn region-of-interest (ROI) method. Materials and Methods: Stress and rest N-13 ammonia cardiac PET imaging was acquired for 23 min in 5 patients with coronary artery disease using GE Advance tomograph. Factor analysis generated physiological TACs and factor images using the normalized TACs from each dixel. Four steps were involved in this algorithm: (a) data preprocessing; (b) principal component analysis; (c) oblique rotation with positivity constraints; (d) factor image computation. Area under curves and MBF estimated using the two compartment N-13 ammonia model were used to validate the accuracy of the factor analysis generated physiological TACs. The MBF estimated by factor analysis was compared to the values estimated by using the ROI method. Results: MBF values obtained by factor analysis were linearly correlated with MBF obtained by the ROI method (slope = 0.84, r = 0.91), Left ventricular blood pool TACs obtained by the two methods agreed well (Area under curve ratio: 1.02 ($0{\sim}1min$), 0.98 ($0{\sim}2min$), 0.86 ($1{\sim}2min$)). Conclusion: The results of this study demonstrates that MBF can be measured accurately and noninvasively with dynamic N-13 ammonia PET imaging and factor analysis. This method is simple and accurate, and can measure MBF without blood sampling, ROI definition or spillover correction.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.1
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• pp.27-33
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• 2007

Purpose: We have performed SRS (stereotactic radiosurgery) for avm (arterry vein malformation) and brain cancer. In order to verify dose and localization of SRS, dose distributions from TPS ($X-Knife^{(R)}$ 3.0, Radionics, USA) and GafChromic $EBT^{(R)}$ film in a head phantom were compared. Materials and Methods: In this study, head and neck region of conventional humanoid phantom was modified by substituting one of 2.5 cm slap with five 0.5 cm acrylic plates to stack the GafChromic $EBT^{(R)}$ film slice by slice with 5 mm intervals. Four films and five acrylic plates were cut along the contour of head phantom in axial plane. The head phantom was fixed with SRS head ring and adapted SRS localizer as same as real SRS procedure. CT images of the head phantom were acquired in 5 mm slice intervals as film interval. Five arc 6 MV photon beams using the SRS cone with 2 cm diameter were delivered 300 cGy to the target in the phantom. Ten small pieces of the film were exposed to 0, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900 cGy, respectively to calibrate the GafChromic $EBT^{(R)}$ film. The films in the phantom were digitized after 24 hours and its linearity was calibrated. The pixel values of the film were converted to the dose and compared with the dose distribution from the TPS calculation. Results: Calibration curve for the GafChromic $EBT^{(R)}$ film was linear up to 900 cGy. The R2 value was better than 0.992. Discrepancy between calculated from $X-Knife^{(R)}$ 3.0 and measured dose distributions with the film was less than 5% through all slices. Conclusion: It was possible to evaluate every slice of humanoid phantom by stacking the GafChromic EBT film which is suitable for 2 dimensional dosimetry, It was found that film dosimetry using the GafChromic $EBT^{(R)}$ film is feasible for routine dosimetric QA of stereotactic radiosurgery.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.575-585
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• 2013

This research was performed to evaluate the recycling feasibility as a construction material of dredged harbor soil mixed with clay and glass frit. Concentration of heavy metals of the dredged soil from D harbor was severly high, showing Zn of 526.0~13,150.1 mg/kg. The dredged soil was maily composed of 48.30 wt% $SiO_2$, 16.60 wt% $Al_2O_3$, 10.10 wt% CaO, 7.75 wt% $Fe_2O_3$. The clay and the glass frit contained 70.82 wt% $SiO_2$ and $Al_2O_3$ 18.78 wt%, and 71.75 wt% $SiO_2$, 13.99 wt% CaO, 8.51 wt% $Na_2O$, respectively. After adding 10~40 wt% to the clay and sintering them at $1,000^{\circ}C$ or $1,100^{\circ}C$, the compressive strength of the sintered specimens showed $132.6{\sim}178.5kgf/cm^2$ or $581.2{\sim}793.7kgf/cm^2$, respectively. In case of SC46 with the addition 40 wt% of the dredged soil to the clay, the compressive strength ($793.7kgf/cm^2$) of specimen sintered at $1,100^{\circ}C$ was over 5 times higher than that at $1,000^{\circ}C$. The specimen mixed with 40 wt% of dredged soil, 60 wt% of clay and 1 wt% of glass frit satisfied the 1st grade standard for clay brick by KS L 4201. The results of all specimens by Korean Standard Leaching Test also satisfied the standard criteria.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.295-302
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• 2014

This study demonstrates a double-path CDI as an alternative of advanced wastewater treatment process. While the CDI typically consists of many pairs of electrodes connected in parallel, the new double-path CDI is designed to have series flow path by dividing the module into two stages. The CFD model showed that the double-path had uniform flow distribution with higher velocity and less dead zone compared with the single-path. However, the double-path was predicted to have higher pressure drop(0.7 bar) compared the single-path (0.4 bar). From the unit cell test, the highest TDS removal efficiencies of single- and double-path were up to 88% and 91%, respectively. The rate of increase in pressure drop with an increase of flow rate was higher in double-path than single-path. At 70 mL/min of flow rate, the pressure drop of double-path was 1.67 bar, which was two times higher than single-path. When the electrode spacing was increased from 100 to $200{\mu}m$, the pressure drop of double-path decreased from 1.67 to 0.87 bar, while there was little difference in TDS removal. When proto type double-path CDI was operated using sewage water, TDS, $NH_4{^+}$-N, $NO_3{^-}$-N and $PO_4{^{3-}}$-P removal efficiencies were up to 78%, 50%, 93% and 50%, respectively.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.467-474
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• 2014

Preliminary design in chemical process furnishes economic feasibility through calculation of both mass balance and energy balance and makes it possible to produce a desired product under the given conditions. Through this design stage, the process possesses unchangeable characteristics, since the materials, reactions, unit configuration, and operating conditions were determined. Unique characteristics could be very economic, but it also implies various potential risk factors as well. Therefore, it becomes extremely important to design process considering both economics and safety by integrating process simulation and quantitative risk analysis during preliminary design stage. The target of this study is LNG liquefaction process. By the simulation using Aspen HYSYS and quantitative risk analysis, the design variables of the process were determined in the way to minimize the inherent explosion risks and operating cost. Instead of the optimization tool of Aspen HYSYS, the optimization was performed by using stochastic optimization algorithm (Covariance Matrix Adaptation-Evolution Strategy, CMA-ES) which was implemented through automation between Aspen HYSYS and Matlab. The research obtained that the important variable to enhance inherent safety was the operation pressure of mixed refrigerant. The inherent risk was able to be reduced about 4~18% by increasing the operating cost about 0.5~10%. As the operating cost increases, the absolute value of risk was decreased as expected, but cost-effectiveness of risk reduction had decreased. Integration of process simulation and quantitative risk analysis made it possible to design inherently safe process, and it is expected to be useful in designing the less risky process since risk factors in the process can be numerically monitored during preliminary process design stage.

• Korean Journal of Agricultural Science
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• v.8 no.1
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• pp.18-28
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• 1981

The purpose of this study was to establish the intergrated control of rice insect pests. Specific objectives were to reveal the diversity of natural enemies in rice field environment, to obtain basic informations of their population dynamics, and to screen the selective insecticides for the conservation of natural enemies. The results of the study were as follows. 1. In numbers of species and in numbers of each species of parasitic Hymenoptera of rice insect pests were more diverse and abundant in rice paddy leeves and banks than paddy fields. Braconid Mymarid and pteromalid were predominated in the field and their population was high during early August to mid September. 2. Of the predatory spiders, Pirata subpiraticus was the largest in number and amounted to 72% of the total, Gnatonarium dentatum, Pachygnatha clerki and Clubiona japonicola were the next. It was also found that P. subpiraticus had three generations in a year. 3. Hence the activities of the predatory spider species and parasitic Hymenoptera were high in early to mid August and September, it would be better promising to avoid chemical applications at this time of periods as possible. 4. The relative toxicity of several insecticides which have been used for the control of brown plant hopper (BPH) showed that P. subpiraticus was 1.1-73.1 times higher than BPH and G. dentatum to P. subpiraticus was 1.1-73.1 times, respectively. 5. Three conventional insecticides, Padan, Diazinon and Carbofuran were screened for toxicity to predatory spider species. The insecticides deffered in their toxicity to the predators. However, Padan was appeared to be the least toxic to the predators.