• Resources Recycling
• /
• v.10 no.4
• /
• pp.42-47
• /
• 2001

Recycling of aluminum dross is a significant issue in domestic aluminum industry. In this study, formed ceramic materials were prepared using aluminum dross mixed with feldspar powders to investigate its application as industrial materials and utilization of aluminum dross. In the prepared sample, feldspar was melted at the sintered temperature, and its phase was trans-formed into amorphous, and spinel ($MgA1_2$$O_4$) phase in the dross was remained clearly. Density of the test specimen Increased from 0.91 to 0.65 gr/㎤ and water absorbance decreased from 2.5 to 1.7f% with increasing of sintered time at the sintered temperature $1220^{\circ}C$ with composition of feldspar 55 wt%, dross 40wt% and bentonite 5 wt%. At the same experimental conditions, bending strength of the test specimen was 10.8 MPa, and heat conductivity was 0.34 W/m.K with sintered time 30 minutes.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.21 no.3
• /
• pp.27-35
• /
• 2011

Design of Sensor nodes in Wireless Sensor Network(WSN) should be considered some properties as electricity consumption, transmission speed, range, etc., and also be needed the protection against various attacks (e.g., eavesdropping, hacking, leakage of customer's secret data, and denial of services). The stream cipher Rabbit, selected for the final eSTREAM portfolio organized by EU ECRYPT and selected as algorithm in part of ISO/IEC 18033-4 Stream Ciphers on ISO Security Standardization recently, is a high speed stream cipher suitable for WSN. Since the stream cipher Rabbit was evaluated the complexity of side-channel analysis attack as 'Medium' in a theoretical approach, thus the method of power analysis attack to the stream cipher Rabbit and the verification of our method by practical experiments were described in this paper. We implemented the stream cipher Rabbit without countermeasures of power analysis attack on IEEE 802.15.4/ZigBee board with 8-bit RISC AVR microprocessor ATmega128L chip, and performed the experiments of power analysis based on difference of means and template using a Hamming weight model.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.6
• /
• pp.1287-1295
• /
• 2015

This research is the study on the comparative evaluation of SPC (Staggered Pedestrian Crossings) vs PC (Pedestrian Crossings) using risk analysis. Accident factor was elicited by survey of driver's and pedestrian's at SPC & PC. I estimated the weight of a risk of violation and a mental burden by AHP (Analytic Hierarchy Process) and compared degree of risk at SPC AND PC. In conclusion, a new alternative plan of a pedestrian crossing system, staggered pedestrian crossing which plays an important role in traffic flow, pedestrian's crossings which plats an important role in traffic flow, pedestrian's convenience and traffic safer is sager than pedestrian crossings the degree of risk used this study doesn't imply an measure of the number of accident and the rate of accident, in estimating the degree of risk of pedestrian crossings, we should analyze more data of accident, behaviors, and road circumstance to include driver's and pedestrian's violation behavior in an estimate index.

• Journal of radiological science and technology
• /
• v.44 no.2
• /
• pp.91-100
• /
• 2021

High-Resolution thoracic CT (HRCT) is a scanning protocol in which thin slice thickness and sharpness algorithm are utilized to enhance image resolution for diagnosis and assessment of interstitial lung disease (ILD). This examination is sometimes performed in both supine and prone position to improve sensitivity to early changes of these conditions. Anatomical structures (the size of lung field and heart and descending aorta) of 150 patients who underwent HRCT were retrospectively compared. HRCT had been conducted in two positions (supine and prone). Data were divided into five groups according to patient body weights (from 40 to more than 80kg, 10kg intervals, 60 patients/each group). Quantitative analysis was utilized in Image J program. In the supine position defined as the control group, the average values of lung fields and heart size and aorta were compared with the prone position defined as the experimental group. The size of the lungs was found to be higher in the supine position, and it was confirmed that there was a statistically significant difference in patients over 70 kg (p<0.05). In addition, both sizes of the heart and descending aorta were larger in prone position, but in the case of the heart, there was no correlation with the presence or absence of ILD disease (p>0.05). Also, the area of prone in the descending aorta was higher than supine position, but there was no statistically significant difference between supine and prone position (p>0.05). In conclusion, when the severity of ILD disease was severe, there was no statistically significant difference in the area difference between supine and prone position, so it is considered that it will be helpful in diagnostic decision.

• Resources Recycling
• /
• v.21 no.5
• /
• pp.31-37
• /
• 2012

As a recovery of elemental silicon from the sludge of Si wafer process, a process of mechanical separation-chlorine roasting-electrolysis has been suggested. The silicon sludge consisted of Si, SiC, machine oil, and metallic impurities. The oil and metal impurities was removed by mechanical separation. The Si-SiC mixture was converted to silicon chloride by chlorine roasting at $1000^{\circ}C$ for 1 hr and the silicon chloride was dissolved into an ionic liquid of $[Bmpy]Tf_2N$ as an electrolyte. Cyclic voltammetry results showed an wide voltage window of pure $[Bmpy]Tf_2N$ and a reduction peak of elemental Si from $[Bmpy]Tf_2N$ dissolved $SiCl_4$ on Au electrode, respectively. The silicon deposits could be prepared on the Au electrode by the potentiostatic electrolysis of -1.9 V vs. Pt-QRE. The elemental silicon uniformly electrodeposited was confirmed by various analytical techniques including XRD, FE-SEM with EDS, and XPS. Any impurity was not detected except trace oxygen contaminated during handling for analysis.

• Korean Journal of Ecology and Environment
• /
• v.53 no.3
• /
• pp.255-264
• /
• 2020

The use of fishway has been investigated up to 2~9 years, continuously each month and over the long term that installed in 6 domestic rivers. The fish's use of fishway has been investigated as direct collection by trap in exit section of the fishway. The population structure of fish using 6 fishway and the fish that live in the river showed difference. About 2 to 7 species of fish took possession of more than 80% of total use of fish in fishways. This seems to be not the results of attraction flow in fishway but specialized result of physiology characteristic followed by species of fish. In addition, the distribution of fish species using fishway was different with the fishways installed in river. This difference seems to be consequence of the place that of the river and fishway types. Generally, the fish species were less and had high ratio of home migratory fish in vertical slot type fishway, which shows relatively fast velocity of water flow. This analysis result of major fish species using fishway can be used in planning fishway and to choose major targeted species for the planning.

• International Journal of Highway Engineering
• /
• v.11 no.3
• /
• pp.13-21
• /
• 2009

The traveler's travel pattern has significantly changed due to the social and economic changes. The travel time among the traveler's pattern is the limited resource. The travelers are trying to maximize the utility of travel with the least travel cost. So, the travelers travel with their own travel time budget in mind, which they can pay or choose to pay for the optimal maximization of the utility of the individuals. This research is to group and extract the specific factors which affect the travel time budget by utilizing the CART analysis method, which enables the analysis of traveler's characteristics and their interrelationship based on the data collected from "2002 Household Travel Practice Research" and then try to derive a model for estimating the traveler’s travel time budget. The result of CART analysis shows that the factors which affect the travel time budget include the traveler's age, size of house, type of house, type of employment, job and relation to the head of household. Considering the affecting factors derived, I developed an estimation model. From that model, we found that the age, size of house and type of house were positively (+) related to the travel time budget while the homeworking people who have less travel frequency as a type of employment were negatively (-) related to it. In particular, from the point of type of job, the housewives, children not yet old enough to attend schools and people who are working in the agricultural, or marine product industries were found to have the negative (-) value while the people who have the administrative, office, management jobs were found to have the positive (+) value.

• Korean Journal of Ecology and Environment
• /
• v.45 no.2
• /
• pp.210-217
• /
• 2012

This study investigated the water quality of effluents from the wastewater treatment plants, located at the Gumi Complex 4, Gumi, and Wonpyong, in Gumi. DOC accounted for higher than 70% of TOC, and oxidation efficiencies, calculated from carbon, were 13~43% for BOD and 37~73% for CODMn, respectively. Based on the biological decomposition experiments, R-DOC account for higher than 70% of DOC, mostly being occupied by refractory organic matters. This indicated that the biodegradable organics occupied more proportions of organic loadings than the refractory organics. The effect of the organics from a discharge of a sewage treatment plant on rivers, Gumi industrial Complex 4, Gumi, and Wonpyong on lower streams of the Nakdong River were found to be 15%, 6% and 16% respectively. The ratio of 15% suggests that comparatively, no large portions of TOC loadings are occupied, but the problem is that the biodegradable organic matters occupy a lot more proportions than that of the refractory organic matters. Thus, it is highly estimated that the refractory organics can gradually increase the pollution level of organics and precursors of disinfection by-products to the down-stream water treatment plants.

• Resources Recycling
• /
• v.14 no.2
• /
• pp.19-27
• /
• 2005

The recycling possibility of aluminum waste dross(AWD) as a ceramic raw material of porous light-weight material was examined. A aluminum waste dross was washed 4-7 consecutive times and roasted at 900$^{\circ}% for 1hour as pre-treatments. The properties of the pre-treatment of aluminum waste dross was investigated. It was conformed by XRD result that the spinel crystalline was grown in AWD, after roasting. After the roasted AWD was ground in aqueous state, the sodium hexaphosphate(SHP) as a dispersant which is used for stabilizing the concentrated slurry was added to the AWD slurry. The porous material was prepared by slurry foaming method with surfactant at room temperature. The foamed slurry volumes were 2 and 3 times of the original slurry volume. The properties of porous material with extended volume of 3 times was following: the porosity was about 84%, bulk density was 0.59 g/cm$^3$, the range of pore was from 50 ${\mu}m$ to 500 ${\mu}m$ and mean pore size was about 200 ${\mu}m$. AWD porous material was sintered at 1150$^{\circ}C-1250$^{\circ}C. It was colcluded that AWD was sintered well at 1200$^{\circ}C from material surface observation by SEM.

• Journal of Korean Society of Transportation
• /
• v.20 no.7
• /
• pp.107-116
• /
• 2002

Crash Cushion is a kind of safety facilities on roadside which acts the role of absorbing impact energy when vehicles are driven out of normal route such as Gore area of freeway off ramp. Criteria for severity index considering accident occurrence possibility are needed to have strong effect on installing the facilities. However, present criteria for establishing crash cushion design do not include such processes. Therefore, the paper presents two kinds of study to develop criteria for severity index. First of all, development of accident forecasting model on freeway off ramp is presented. The module is a relationship between accidents and road environment by negative binomial distribution (NB) which is called to reflect very well quality of accidents at Gore of crash cushion installed freeway Secondly, freeway exiting behavior model is developed because the human factor is the most important one. However, many literatures have shown between road environment and accidents which are more quantitative than human factor. The study supposed advanced process steps on actual freeway and analysed correlation between variables and accidents. The criteria for severity index is presented to determine whether to install or not by benefit cost analysis for each module. The standard for severity index will help to determine whether to install the crash cushion or not and to estimate severity for freeway and off ramp.