• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.538-544
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• 2000

A phased array ultrasonic nondestructive inspection system is being developed to obtain images of the interior of steel structures by modifying a medical ultrasound imaging system. The medical system consists of 64 individual transceiver channels that can drive 128 array elements. Several modifications of the system were required mainly due to the change of sound speed. It was necessary to fabricate array transducers for steel structure and to obtain A-scan signal that is necessary for the nondestructive testing. Boundary diffraction wave model was used for the prediction of radiation beam field from array transducers, which provided guidelines to design array transducers. And a RF data acquisition board was fabricated for the A-scan signal acquisition along a selected un line within an image. For the proper beam forming in the transmission and reception for steel structure, delay time was controlled. To demonstrate the performance of the developed system and fabricated transducers, images of artificial specimens and A-scan signals for selected scan lines were obtained in a real time fashion.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.546-553
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• 2012

Urushiol extracted from lacquer tree exhibits good thermal stabilities as well as antimicrobial andantioxidant properties. However, it has been known that the urushiol derivates bring out allergy. In this study, polyurushiol (PUOH) powders were successfully synthesized for the safe and convenient handling of allergic urushiol. First, the as-synthesized PUOH was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analyzer (TGA), antioxidant test and antimicrobial test. And then, six different LDPE/PUOH composite films were prepared via a twin screw extruder system and investigated their feasibility to use as active packaging materials. Their chemical structures, morphology, thermal optical and antimicrobial properties of the LDPE/PUOH composite films were investigated as a function of PUOH contents. FTIR and SEM results showed that LDPE/PUOH composite films have a weak interfacial interaction and poor dispersion with a high PUOH loading. The thermal properties increased up to 3 wt% as the content of PUOH increases. Compared to the pure LDPE films, LDPE/PUOH composite films are more effective in the UV absorbance and antibacterial activity against E. coli. To maximize the performance of LDPE/PUOH compositefilms as the packaging materials, further researches are required to enhance the dispersion of PUOH powders in the LDPE matrix.

• Korean Journal of Food Science and Technology
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• v.42 no.2
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• pp.130-135
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• 2010

Picrate, enzyme-picrate and instrumental analysis methods using IC (Ion Chromatography) and HPLC (High Performance Liquid Chromatography) were compared for their effectiveness in determining cyanide in extracts of Maesil, which is classified as a harmful substance. First, the picrate method showed the shortest analysis time (about 5 hr). The color of picrate paper changed at 0.01 mg/$200\;mL\;CN^-$. However, it was difficult to detect cyanide from amygdalin of glucosides. Second, we performed a qualitative analysis for total cyanide (free cyanide and cyanide from amygdalin) by the enzyme-picrate method using $\beta$-glucosidase and a quantitative analysis by spectrophotometry. Finally, analysis of cyanide by IC and HPLC required the longest determining time (about 17 hr) as well as pretreatment for each free cyanide and amygdalin. These results suggest that enzyme-picrate is the most effective analysis method for the detection of cyanide in Maesil extracts.

• Proceedings of the KSCN Conference
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• 2003.11a
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• pp.1048-1048
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• 2003

The purpose of this study was to investigate dietary behaviors, body image, hematological index and nutrient intake of female athletes in Incheon. The subjects were 112 female athletes (field and track: n=32, firing: n=27, fencing: n=29, swimming: n=14, badminton: n=10) from middle and high schools in Incheon. This cross-sectional study was conducted by a self-administered questionnaire. Fasting blood samples were obtained and analyzed for hemoglobin (Hb), hematocrit(Hct), ferritin, serum iron, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), unsaturated iron binding capacity (UBC), total iron binding capacity (TIBC) and transferrin saturation (TS). Nutrient intakes collected from 3 day-recalls were analyzed by the Computer Aided Nutritional Analysis Program. Statistical analysis was conducted using SPSS 10.0 program. The results are summarized as follows: Average age of field and track athletes, firing, fencer and swimmer was 14 years and that of badmintoner was 17 years. Most of female athletes had dietary problems such as unbalanced meals, skipping meals, and preference of processed foods. More than 60% of female athletes skipped breakfast. As for perception of body image, most of female athletes perceived themselves fatter compared to normal body image. Especially, field and track athletes were more significantly experienced weight control compared to the other athletes (p<0.05). As for physical burden during exercise, 56.3% of swimmer and 31.3% of field and track athletes answered “very hard”, which showed a significant difference (p<0.001) More than 80% of female athletes had experienced a vertigo during exercise (p<0.01). Also, more than 50% of female athletes except badmintoner had experienced an irregular menstruation (p<0.05). Average serum iron level (p<0.05) and TS (p<0.05) of field and track athletes were significantly lower compared to the other athletes. Serum ferritin of badmintoner, field and track athletes and fencer was significantly lower compared to firing and swimmer (p<0.05). Nutrient intakes of female athletes except vitamin B6, niacin and phosphorus were lower than the Korean RDA. Especially, calcium and iron intakes of female athletes were under the 50% of the Korean RDA. Therefore, proper nutrition education and supplementation are required for female athletes to encourage desirable food habits as well as to improve their nutritional status and exercise performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.133-140
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• 2016

The Ministry of Land, Infrastructure and Transport has introduced low-floor buses, which are convenient for passengers getting on and off the bus and for the handicapped. The standard bus model is 11 m long and uses compressed natural gas (CNG). However, this model has drawbacks in narrow rural road conditions such as those in farming and fishing villages and mountainous areas, as well as difficulty in refueling since CNG facilities are not readily available. In this study, running resistance values were obtained by coasting performance tests on actual roads using a Tata Daewoo LF-40 model with three different weight conditions: curb vehicle weight (CVW), half vehicle weight (HVW), and gross vehicle weight (GVW).The test methods include WHVC, NIER-06, and constant-speed driving at 60 km/h. These tests were used to measure the fuel economy of vehicles other than the target vehicles to obtain the combined fuel economy. The energy efficiency was highest in the case of CVW. In the WHVC mode, the fuel consumption rates of HVW and GVW were typically 3.5% and 12% higher than that of CVW, respectively. In constant-speed driving, the fuel efficiency of HVW was higher than that of CVW. Further research is required to analyze the exhaust gas data.

• Journal of Advanced Navigation Technology
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• v.10 no.3
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• pp.275-281
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• 2006

Simple-relay aided resource allocation (SRARA) schemes are incorporated with throughput guarantee scheduling (TGS) in IEEE 802.16 type time division duplex - orthogonal frequency division multiple access (TDD-OFDMA) downlink in order to enhance service coverage, where the amount of resources for relaying at each relay is limited due to either its available power which is much smaller than base station (BS) power or the overhead required for exchanging feedback information. The performance of SRARA schemes is evaluated with schedulers such as proportional fair (PF) and TGS at 64kbps and 128kbps user throughput requirements when total MS power is set to 500mW or 1 W. For 64kbps throughput requirement level, more improvement comes from relay than scheduler design. For 128kbps case, it comse from scheduler design than relay due to the fact that simple relay can't help using strictly limited amount of resources for relaying function.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.593-599
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• 2013

In this paper, the GPS cycle-slip detection for carrier-phase based positioning of land vehicle is presented. For the carrier phase based positioning, cycle-slip detection is necessary to get the reliability of positioning result. There exists many cycle-slip detection algorithms, but we detect the cycle-slip by using the monitoring value which is defined as residual between the carrier phase measurement and estimated value from low-cost inertial sensor. To achieve goal of paper, low-cost cycle-slip detection system, permissible specification region of inertial sensor is derived. By using the result of permissible region, appropriate inertial sensor of cycle-slip detection can be decided, proper cost and proper specification. To verify the result of this paper, we conduct the rate table test. As a result, required cycle-slip detection performance is satisfied conservatively.

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.289-299
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• 2009

This study set out to analyze the perceptions of investigative police officers and division police officers regarding Police Investigation Specialization, which had been in effect for four years, identify the problems, and search for alternative policies. The results led to the following alternative policies; first, the communication among the members should be facilitated by trading the jobs between investigative policemen and division members in certain percentage regularly, integrating job education and special work, and developing diverse support programs for detective activities to provide them with opportunities to experience and understand investigation. The second suggestion concerns the investigation members' morale. There should be a range of measures to boost their moral such as allocating separate budget and personnel to support the investigation department and the treatment of major criminal and civil cases, giving each investigation team an office and investigation room to improve their working environment, readjusting the promotion ratio of Police Investigation Specialization to introduce a promotion system proper for each investigation's characteristics. The third suggestion is to secure job efficiency. It's required to reinforce the current short-term specialized education program to bring up practical and professional investigators, open the certification exam of professional investigators to all members so that every policeman can have their abilities recognized and approved as long as they have the demanded capabilities, and create a system of shedding off the members idle at work by reflecting low performance records when evaluating the members to decide who to dismiss from Police Investigation Specialization. And finally, it's important to divide duties rationally. The rationality of duties division can be guaranteed by setting the guidelines for direct handling for the team leader to help him devote himself to his duties, defining objective criteria of measuring investigation workload, and creating devoted systems and teams for simple and small accidents so that experienced investigators can deal with high-profile cases.

• Journal of Drive and Control
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• v.13 no.2
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• pp.10-18
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• 2016

A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements to mechanize routine agricultural tasks. When the FEL is used with a loaded bucket, careful operation is required to maintain safety and avoid spillage when the tractor passes a bump because a change in the gravity center of the tractor due to varied loadings can affect the stability of the tractor. Use of a boom suspension system consisting of accumulators and orifice dampers can be instrumental in reducing pitching vibrations while increasing the handling performance of the FEL-mounted tractor. The objective of this research was to reduce bump shocks by adding an orifice and a flow control valve to the original hydraulic circuit composed solely of accumulators. A simulation study was performed using the SimulationX program to investigate the effects of an accumulator and an orifice-throttle damper on bump shocks. Results showed that the peak pressure on a boom cylinder and the vertical acceleration of a bucket were significantly affected by use of both an accumulator and an orifice damper. In a field test conducted with a 75-kW tractor, the peak pressure of the boom cylinder, and the root mean square (RMS) vertical acceleration of the bucket and seat were reduced by on average, 23.0, 42.2, and 44.9% respectively, as compared to those measured with the original accumulator system, showing that an improved design for the accumulator hydraulic circuit can reduce bump shocks. Further studies are needed to design a tractor suspension system that includes the effects of cabin suspension and tires as well as dynamic analysis.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.37-45
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• 2015

In modern electronic warfare systems, a demand on the more accurate estimation method based on TDOA and FDOA has been increased. TDOA/FDOA localization consists of two-stage procedures: the extraction of information from signals and the estimation of emitter location. Various algorithms based on CAF(complex ambiguity function), which is known as a basic method, has been presented in the area of extractions. When we extract TDOA and FDOA information using a conventional method based on the CAF algorithm from communication signals, considerably long integration time is required for the accurate position estimation of an unknown emitter far from sensors more than 300 km. Such long integration time yields huge amount of transmission data from sensors to a central processing unit, resulting in heavy computiational complexity. Therefore, we theoretically analyze the integration time for TDOA/FDOA information using CRLB and propose a two-stage global optimization algorithm which can minimize the transmission time and a computational complexity. The proposed method is compared with the conventional CAF-based algorithms in terms of a computational complexity and the CRLB to verify the estimation performance.