• Korean Journal of Agricultural Science
• /
• v.12 no.1
• /
• pp.118-127
• /
• 1985

The grain temperature is a crucial factor determining the deterioration rate of stored grain. Therefore, it is used to be predicted in order to evaluate the various stored methods rapidly and inexpensively. In this study, a mathematical model was developed to simulate the temperatures of grain stored in a cylinderical bin. It was formulated for the two dimensional heat transfer by the finite difference method. Then, it was verified statistically using the actual test deta and the predicted. The changes of grain temperature were analyed using the simulated data of one year for a safe stoarge and the following results were obtained: 1. Simulation model developed by the finite difference method was validated with the actual and the predicted grain temperatures and it's result showed that it could predict the grain temperature of storage bin reasonably well. 2. Grain temperature near the wall of storage bin were changed with $6-7^{\circ}C$ higher then average atmospheric temperature from June to September. Therefore, the parts of stored grain near the wall is supposed to be deteriorated fast. 3. When the dimension of bin diameter is about the same as the bed height, the changes of grain temperature of radial direction was higher than the verticals. 4. The predicted temperature showed that the grain temperature of which were from the end of April to mid October were higher than the safe storage limit at Yusung, Korea.

• The Journal of Korean Society for Radiation Therapy
• /
• v.21 no.1
• /
• pp.33-39
• /
• 2009

Purpose: The aim of this study is to compare patient's body posture and its position at the time of simulation with one at the treatment room using On-board Imaging (OBI) and CT (CBCT). The detected offsets are compared with position errors of Rando Phantom that are practically applied. After that, Rando Phantom's position is selected by moving couch based on detected deviations. In addition, the errors between real measured values of Rando Phantom position and theoretical ones is compared. And we will evaluate target position's accuracy of KV X-ray imaging's 2D and CBCT's 3D one. Materials and Methods: Using the Rando Phantom (Alderson Research Laboratories Inc. Stanford. CT, USA) which simulated human body's internal structure, we will set up Rando Phantom on the treatment couch after implementing simulation and RTP according to the same ways as the real radioactive treatment. We tested Rando Phantom that are assumed to have accurate position with different 3 methods. We measured setup errors on the axis of X, Y and Z, and got mean standard deviation errors by repeating tests 10 times on each tests. Results: The difference between mean detection error and standard deviation are as follows; lateral 0.4+/-0.3 mm, longitudinal 0.6+/-0.5 mm, vertical 0.4+/-0.2 mm which all within 0~10 mm. The couch shift variable after positioning that are comparable to residual errors are 0.3+/-0.1, 0.5+/-0.1, and 0.3+/-0.1 mm. The mean detection errors by longitudinal shift between 20~40 mm are 0.4+/-0.3 in lateral, 0.6+/-0.5 in longitudinal, 0.5+/-0.3 in vertical direction. The detection errors are all within range of 0.3~0.5 mm. Residual errors are within 0.2~0.5 mm. Each values are mean values based on 3 tests. Conclusion: Phantom is based on treatment couch shift and error within the average 5mm can be gained by the diminution detected by image registration based on OBI and CBCT. Therefore, the selection of target position which depends on OBI and CBCT could be considered as useful.

• Journal of the Institute of Convergence Signal Processing
• /
• v.9 no.1
• /
• pp.31-38
• /
• 2008

Ad-Hoc network is a network architecture which has no backbone network and is deployed temporarily and rapidly in emergency or war without fixed mobile infrastructures. All communications between network entities are carried in ad-hoc networks over the wireless medium. Due to the radio communications being extremely vulnerable to propagation impairments, connectivity between network nodes is not guaranteed. Therefore, many new algorithms have been studied recently. This study proposes the secondary header approach to the cluster based routing protocol (CBRP). The primary header becomes abnormal status so that the primary header can not participate in the communications between network entities, the secondary header immediately replaces the primary header without selecting process of the new primary header. This improves the routing interruption problem that occurs when a header is moving out from a cluster or in the abnormal status. The performances of proposed algorithm ACBRP(Advanced Cluster Based Routing Protocol) are compared with CBRP. The cost of the primary header reelection of ACBRP is simulated. And results are presented in order to show the effectiveness of the algorithm.

• Restorative Dentistry and Endodontics
• /
• v.30 no.2
• /
• pp.79-85
• /
• 2005

The purpose of this study was to evaluate the obturation efficiency of a non-standardized gutta-percha cone in curved root canals prepared with 0.06 taper nickel-titanium instruments. Sixty simulated curved root canals in clear resin blocks were prepared with crown-down technique using 0.06 taper rotary $ProTaper^{TM}$and ProFile (Dentsply-Maillefer) until apical canal was size 30. Root canals were randomly divided into 4 groups of 15 blocks and obturated with cold-laterally compacted gutta-percha technique by using either a non-standardized size medium gutta-percha cone or an ISO-standardized size 30 one as a master cone. Gutta-percha area ratio were calculated at apical levels of 1, 3 and 5 mm using AutoCAD 2000 after cross-sectioning, and the data were analyzed with one-way and two-way ANOVAs and Duncan's multiple range test. Non-standardized size medium cone groups showed significantly higher gutta-percha area ratio than standardized cone groups at all apical levels (p < 0.01). Non-standardized cone groups used significantly less accessory cones than standardized cone groups (p < 0.01).

• Korean Chemical Engineering Research
• /
• v.45 no.6
• /
• pp.656-662
• /
• 2007

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.7 no.1
• /
• pp.7-15
• /
• 2000

To assess the accuracy of blood pressure measurement in general hospital nurses, 276 nurses at four hospital in Kyungju city and Pohang city were observed during the study period 20 December 1998 to 29 December 1998. The nurses measuring the blood pressure of simulated patient's were checked by the researcher or 20 items, that are recommended for consideration when doing a blood pressure measurement. Of the six items in the preparation step for measuring blood pressure, the accuracy of 'patients shouldn't talk during the procedure' had the lowest frequency(27.1%) and the other five items were above 80%. Of the ten items on blood pressure measuring technique, the accuracy of the frequency for 'inflating the cuff until the radial or brachial artery pulse is no longer palpable and then adding 30mmHg' was 0%, 'waiting $30{\sim}60$ seconds before reinflating the cuff' was alse 0%, 'rapidly deflating the cuff', 0.3%, 'rapidly and steadily inflating the cuff to the maximal level as per above-mentioned initial systolic pressure assessment step', 0.7%, 'reading the pressure to the nearest 2mmHg mark on the manometer', 10.8%, the remaining items were above 70%. Of the four items on blood pressure recording, the accuracy of 'recording the cuff size' had a frequency of 0.3%, 'recording the patient's position such as sitting, standing or lying position', 10.8%, 'recording the arm or leg which was used for measuring the blood pressure', 53.6%, and 'recording systolic/diastolic pressure', 100%. The variables significantly related to the accuracy of the blood pressure measurement were age, career position at hospital, and qualification education for blood pressure measurement(p<0.01). In the multiple regression analysis, position and qualification education were significant variables(p<0.01). In conclusion, the accuracy of blood pressure measurement was very low, thus, qualification education for blood pressure measurement should be done immediately to improve the accuracy of measurement by nurses in general hospitals.

• The Journal of Korean Academy of Prosthodontics
• /
• v.49 no.4
• /
• pp.324-332
• /
• 2011

Purpose: The purpose of this study was to compare the stress distribution of teeth and jaw on load by differentiating property of materials according to each layer of widely used mouthguard. Materials and methods: A Korean adult having normal cranium and mandible was selected to examine. A customized mouthguard was constructed by use of DRUFOMAT plate and DRUFOMAT-TE/-SQ of Dreve Co. according to Signature Mouthguard system. The cranium was scanned by means of computed tomography with 1mm interval. It was modeled with CANTIBio BIONIX/Body Builder program and simulated and interpreted using Alter HyperMesh program. The mouthguard was classified as follows according to the layers. (1) soft guard (Bioplast)(SG) (2) hard guard (Duran)(HG) (3) medium guard (Drufomat)(MG) (4) soft layer + hard layer (SG + HG) (5) hard layer + soft layer (HG + SG) (6) soft layer + hard layer + soft layer (SG + HG + SG) (7) hard layer + soft layer + hard layer (HG + SG + HG) The impact locations on mandible were gnathion, the center of inferior border, and the anterior edge of gonial angle. And the impact directions were oblique ($45^{\circ}$). The impact load was 800 N for 0.1 sec. The stress distribution was measured at maxillary teeth, TMJ and maxilla. The statistics were conducted using Repeated ANOVA and in case of difference, Duncan test was used as post analysis. Results: In teeth and maxilla, the mouthguard contacting soft layer of mandibular teeth presented lowest stress measure and, in contrast, in condyle, the mouthguard contacting hard layer of mandibular teeth presented lowest stress measure. Conclusion: For all impact directions, soft layer + hard layer + soft layer, the mouthguard with three layers which the hard layer is sandwiched between two soft layers, showed relatively even distribution of stress in impact.

• Membrane Journal
• /
• v.21 no.1
• /
• pp.22-29
• /
• 2011

During the maintenance, repair and replacement process of circuit breaker, $SF_6$ reacted with input air in arc discharge, which led to the production of by-product gases (eg, $N_2$, $O_2$, $CF_4$, $SO_2$, $H_2O$, HF, $SOF_2$, $CuF_2$, $WO_3$). Among these various by-product gases, $N_2$, $O_2$, $CF_4$ is major component. Therefore, the effective separation process is necessary to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. In this study, the membrane separation process was applied to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. The concentration of $SF_6$ gas in gas produced from the electric power industry is over than 90 vol%. Therefore, we made the simulated gas containing $N_2$, $O_2$, $CF_4$, $SF_6$ which the concentration of $SF_6$ gas is minimum 90 vol%. From the results of membrane separation process of $SF_6$ gas from $N_2$, $O_2$, $CF_4$ $SF_6$ mixture gases, PSF membrane shown the highest recovery efficiency 92.7%, in $25^{\circ}C$ and 150 cc/min of retentate flow rate. On the other hand, PC membrane shown the highest recovery efficiency 74.8%, in $45^{\circ}C$ and 150 cc/min of retentate flow rate. Also, the highest rejection rate of $N_2$, $O_2$, $CF_4$ is 80, 74 and 58.9% seperately in the same operation condition of highest recovery efficiency. From the results, we supposed the membrane separation process as the effective $SF_6$ separation and recycle process from the mixture gas containing $N_2$, $O_2$, $CF_4$, $SF_6$.

• Journal of the Korean Institute of Gas
• /
• v.17 no.4
• /
• pp.58-69
• /
• 2013

This paper presents production data analysis for two production wells located in the shale gas field, Canada, with the proper analysis method according to each production performance characteristics. In the case A production well, the analysis was performed by applying both time and superposition time because the production history has high variation. Firstly, the flow regimes were classified with a log-log plot, and as a result, only the transient flow was appeared. Then the area of simulated reservoir volume (SRV) analyzed based on flowing material balance plot was calculated to 180 acres of time, and 240 acres of superposition time. And the original gas in place (OGIP) also was estimated to 15, 20 Bscf, respectively. However, as the area of SRV was not analyzed with the boundary dominated flow data, it was regarded as the minimum one. Therefore, the production forecasting was conducted according to variation of b exponent and the area of SRV. As a result, estimated ultimate recovery (EUR) increased 1.2 and 1.4 times respectively depending on b exponent, which was 0.5 and 1. In addition, as the area of SRV increased from 240 to 360 acres, EUR increased 1.3 times. In the case B production well, the formation compressibility and permeability depending on the overburden were applied to the analysis of the overpressured reservoir. In comparison of the case that applied geomechanical factors and the case that did not, the area of SRV was increased 1.4 times, OGIP was increased 1.5 times respectively. As a result of analysis, the prediction of future productivity including OGIP and EUR may be quite different depending on the analysis method. Thus, it was found that proper analysis methods, such as pseudo-time, superposition time, geomechanical factors, need to be applied depending on the production data to gain accurate results.

• Journal of Bio-Environment Control
• /
• v.14 no.2
• /
• pp.95-105
• /
• 2005

This study was carried out to file up using effect and requirement of energy for environmental design data of Pleurotus eryngii growing houses. Heating and cooling Degree-Hour (D-H) were calculated and compared for. some Pleurotus eryngii growing houses of sandwich-panel (permanent) o. arch-roofed(simple) type structures modified and suggested through field survey and analysis. Also thermal resistance (R-value) was calculated for the heat insulating and covering materials of the permanent and simple-type, which were made of polyurethane or polystyrene panel and $7\~8$ layers heat conservation cover wall. The variations of heating and cooling D-H simulated for Jinju area was nearly linearly proportional to the setting inside temperatures. The variations of cooling D-H was much more sensitive than those of heating D-H. Therefore, it was expected that the variations of required energy in accordance with setting temperature or actual temperature maintained inside of the cultivation house could be estimated and also the estimated results of heating and cooling D-H could be effectively used far the verification of environmental simulation as well as for the calculation of required energy amounts. When the cultivation floor areas are all equal, panel type houses to be constructed by various combinations of materials were found to by far more effective than simple type pipe house in the aspect of energy conservation maintenance except some additional cost invested initially. And also the energy effectiveness of multi-span house compared to single span together with the prediction of energy requirement depending on the level insulated for the wall and roof area could be estimated. Additionally, structural as well as environmental optimizations are expected to be possible by calculating periodical and/or seasonal energy requirements for those various combinations of insulation level and different climate conditions, etc.