• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.299-307
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• 2023

In the midst of accelerating wars around the world, unmanned robot technology that can guarantee the safety of human life is emerging. ERP-42 is a modular platform that can be used according to the application. In the field of defense, it can be used for transporting supplies, reconnaissance and surveillance, and medical evacuation in conflict areas. Due to the nature of the military environment, atypical environments are predominant, and in such environments, the platform's path followability is an important part of mission performance. This paper focuses on reducing the minimum turning radius in terms of improving path followability. The minimum turning radius of the existing 2WS/2WD in-wheel platform was reduced by increasing the torque of the independent driving in-wheel motor on the rear wheel to generate oversteer. To determine the degree of oversteer, two GPS were attached to the center of the front and rear wheelbases and measured. A closed-loop speed control method was used to maintain a constant rotational speed of each wheel despite changes in load or torque.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.130-140
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• 2000

In this paper the reference model following control(RMFC) scheme through the optimal control theory is investigated for the independent rear wheel steering(IRWS) vehicle. RMFC vehicle follows the dynamic performance of a virtual vehicle as a reference model deisgned in the controller. Linear vehicle model of two degres-of-freedom is used to derive control scheme which is applied to full vehicle for evaluating handling performances. And 4WS vehicle through RMFC is compared to the conventional 2WS vehicle and 4WS vehicle in the J-turn test. The RMFC logic is also extended to IRWS vehicle, IRWS with RMFC shows not only the excellent handling performance but salso some advantages in terms of the directional stability and responsiveness from the simulation results.

• Journal of Plant Biology
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• v.13 no.1
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• pp.47-55
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• 1970

In order to approach a reasonable method for the indirect estimation of the productivity in terrestrial plants, allometric method was studied with herbs, such as Boenmeria frutescens and Hibiscus mutabilis, and scrubs, such as Robinia pseud oacacia and Morus alba f. Hchiroe. Allometric relations between D230H, square of the stem(or shoot) diameter(D30) on 30cm height above ground multiplied by stem length(H), and the amount of the stem(Ws), orof the leaves per stem, were fitted to each material plant with linear regression. The allometric coefficient in relation of D230H to Ws was approximated between scrubs having different life form, and the allometric function in relation of DF2 to WL was common between herbs in spite of having different growth habitat. As the allometries between D230H and Ws or WL were changeable with the seasonal change it funciton should be calculated repeatedly whenever investigating the standing crop of such community. It is able to utilize an indirect value of D30 obtained from the allometry between D30 and H because direct measurement of D30 in the field is accompanied by troublesome and waste of much time.

• Journal of Information Technology and Architecture
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• v.10 no.2
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• pp.159-167
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• 2013

Web Services offer many benefits over other types of middleware in distributed computing. However, usage of Web Services results in large network bandwidth since Web Services use XML-based protocol which is heavier than binary protocols. Even though there have been many researches to minimize the network traffic and bandwidth usages of Web Services messages, none of them are solving problem clearly yet. In this paper, we propose a transparent proxy with cache to avoid transfer of repeated SOAP data, sent by Web Service to an application. To maintain the cache consistency, we introduce publish/subscribe paradigm using WS-Eventing between the proxy and Web Service. The implemented system based on our proposed architecture will not compromise the standards of Web Service. The evaluation of our system shows that caching SOAP messages not only reduces the network traffic but also decreases the request delays.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1523-1531
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• 2011

Multi-axle driving vehicle are favored for military use in off road operations because of their high mobility on extreme terrains and obstacles. Especially, Military Vehicle needs an ability to driving on hills of 60% angle slope. This paper presents the improvement of the ability of hill climbing for 6WD/6WS vehicle through the optimal tire force distribution method. From the driver's commands, the desired longitudinal force, the desired lateral force, and the desired yaw moment were obtained for the hill climbing of vehicle using optimal tire force distribution method. These three values were distributed to each wheel as the torque based on optimal tire force distribution method using friction circle and cost function. To verify the performance of the proposed algorithm, the simulation is executed using TruckSim software. Two vehicles, the one the proposed algorithm is implemented and the another the tire's forces are equivalently distributed, are compared. At the hill slop, the ability to driving on hills is improved by using the optimum tire force distribution method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.3
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• pp.394-399
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• 2017

To resolve environmental pollution caused by synthetic packaging materials, biodegradable films have been studied as an alternative. In this study, we prepared rockfish skin gelatin (RFG) and nano-clay (Cloisite $Na^+$ and Cloisite 10A) composite films to compare the effects of nano-clay on the physical properties of RFG film. Gelatin was extracted from rockfish skin and used to prepare RFG film with sorbitol as a plasticizer. Tensile strength (TS), water vapor permeability (WVP), and water solubility (WS) of the RFG film were 15.0 MPa, $2.70{\times}10^{-9}g\;m/m^2\;s\;Pa$, and 53.8%, respectively. Addition of nano-clay to the RFG film increased TS and decreased WVP and WS. The X-ray diffraction analysis and scanning electron microscopic results suggest that RFG/nano-clay composite films formed an exfoliated structure. These results indicate that RFG/nano-clay composite films can be applied as biodegradable packaging materials in the food industry.

• Journal of Radiation Protection and Research
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• v.48 no.4
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• pp.184-196
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• 2023

Background: Radiation protection is crucial in various fields due to the harmful effects of radiation. Shielding is used to reduce radiation exposure, but gamma radiation poses challenges due to its high energy and penetration capabilities. Materials and Methods: This work investigates the radiation shielding properties of polyvinylidene fluoride (PVDF) samples containing different weight fraction of tungsten carbide (WC), tungsten trioxide (WO₃), and tungsten disulfide (WS₂). Parameters such as the mass attenuation coefficient (MAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Z_eff), and macroscopic effective removal cross-section for fast neutrons (Σ_R) were calculated using the Phy-X/PSD software. EpiXS simulations were conducted for MAC validation. Results and Discussion: Increasing the weight fraction of the additives resulted in higher MAC values, indicating improved radiation shielding. PVDF-xWC showed the highest percentage increase in MAC values. MFP results indicated that PVDF-0.20WC has the lowest values, suggesting superior shielding properties compared to PVDF-0.20WO₃ and PVDF-0.20WS₂. PVDF-0.20WC also exhibited the highest Z_eff values, while PVDF-0.20WS₂ showed a slightly higher increase in Z_eff at energies of 0.662 and 1.333 MeV. PVDF-0.20WC has demonstrated the highest Σ_R value, indicating effective shielding against fast neutrons, while PVDF-0.20WS₂ had the lowest Σ_R value. The Monte Carlo N-Particle Transport version 5 (MCNP5) simulations showed that PVDF-xWC attenuates gamma radiation more than pure PVDF, significantly decreasing the dose equivalent rate. Conclusion: Overall, this research provides insights into the radiation shielding properties of PVDF mixtures, with PVDF-xWC showing the most promising results.

• Food Science and Biotechnology
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• v.14 no.1
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• pp.68-72
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• 2005

Moisture sorption characteristics of edible composite films were determined and compared against moisture barrier properties. Edible composite films were Z1 (zein film with polyethylene glycol(PEG) and glycerol), Z2 (zein film with oleic acid), ZA1 (zein-coated high amylose corn starch film with PEG and glycerol), and ZA2 (zein-coated high amylose corn starch film with oleic acid). Z2 film showed the lowest equilibrium moisture content (EMC), monolayer value ($W_m$), water vapor permeability (WVP), and water solubility (WS). Surface structure of Z2 was relatively denser and finer than that of other edible films. GAB $W_m$ and C values decreased, while K values increased with increasing temperature. Correlation coefficients of WS:EMC and WVP:EMC at Aw 0.75 were higher than those of WS: $W_m$ and WVP: $W_m$, respectively. EMC values at Aw 0.75 appeared useful for evaluating or predicting moisture barrier properties of edible films.

• Journal of Trauma and Injury
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• v.18 no.1
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• pp.33-40
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• 2005

Background: This study compared the performance of trauma care in an urban and a suburban hospital before and after the enhancement of emergency and intensive care. Method: The medical records of patients who were admitted to the intensive care unit following trauma from 1994 to 1995 and from 2002 to 2003 were examined. The standardized W (Ws), the 95% confidence interval (CI) of the Ws, and the predicted survival rate (Ps) were calculated. During each period, each hospital's actual survival rate was compared with the 95% CI of the Ps according to the revised trauma score (RTS) and injury severity score (ISS). Spell out RTS and ISS. Result: From 1994 to 1995, 225 and 121 records from the urban and the suburban hospitals were reviewed, respectively. The 95% CI's of the Ws were -2.30 to 2.73 and -11.40 to -5.90, respectively. The actual survival rate of the suburban hospital was significantly lower than the predicted survival rate at all RTS. From 2002 to 2003, 315 and 268 records from the urban and the suburban hospitals were reviewed, respectively. The 95% CI's of the Ws was -3.56 to 0.24 and -3.73 to 0.26, respectively. There was no difference between the actual survival rate and the predicted survival rate. Conclusion: An enlargement of the capacities of emergency and intensive care may improve the performance of trauma care at a small suburban hospital.

• Journal of Powder Materials
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• v.15 no.4
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• pp.314-319
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• 2008

Nano-sized tungsten disulfide ($WS_2$) powders were synthesized by chemical vapor condensation (CVC) process using tungsten carbonyl ($W(CO)_6$) as precursor and vaporized pure sulfur. Prior to the synthesis of tungsten disulfide nanoparticles, the pure tungsten nanoparticles were produced by same route to define the optimum synthesis parameters, which were then successfully applied to synthesize tungsten disulfide. The influence of experimental parameters on the phase and chemical composition as well as mean size of the particles for the produced pure tungsten and tungsten disulfide nanoparticles, were investigated.