• Journal of the Korea Society for Simulation
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• 제33권2호
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• pp.37-44
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• 2024

The Korean Helicopter Development Program has successfully introduced the Surion helicopter, a versatile multi-domain operational aircraft that replaces the aging UH-1 and 500MD helicopters. Specifically designed for maneuverability, the Surion plays a crucial role in low-altitude tactical maneuvers for personnel transportation and specific missions, emphasizing the helicopter's survivability. Despite the significance of its low-altitude tactical maneuver capability, there is a notable gap in research focusing on multi-mission tactical maneuvers that consider the risk factors associated with deploying the Surion in the presence of enemy air defenses. This study addresses this gap by exploring a method to enhance the Surion's low-altitude maneuvering paths, incorporating information about enemy air defenses. Leveraging the Proximal Policy Optimization (PPO) algorithm, a reinforcement learning-based approach, the research aims to optimize the helicopter's path planning. Visualized experiments were conducted using a Surion model implemented in the Unity environment and ML-Agents library. The proposed method resulted in a rapid and stable policy convergence for generating optimal maneuvering paths for the Surion. The experiments, based on two key criteria, "operation time" and "minimum damage," revealed distinct optimal paths. This divergence suggests the potential for effective tactical maneuvers in low-altitude situations, considering the risk factors associated with enemy air defenses. Importantly, the Surion's capability for remote control in all directions enhances its adaptability in complex operational environments.

• Asian-Australasian Journal of Animal Sciences
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• 제18권11호
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• pp.1535-1541
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• 2005

Five broiler chicken lines, namely HC, BPB2, CPB2, PB2 and UM1, involving in a selection program and differing in selection intensity and genetic background, were screened for randomly amplified polymorphic DNA (RAPD) polymorphism using 10 selected decamer primers. Nine primers amplified the genomic DNA, generating 200 to 2,500 bp and all detected polymorphism between lines. Out of 74 bands scored using these primers, 34 (50.0%) were found to be polymorphic. The number of polymorphic loci ranged from 3 to 6 with an average of 4.33. Lines differed considerably for within-population genetic similarity estimated by band frequency (WS = 93.55 to 99.25). Between-line genetic similarity estimates based on band sharing as well as on band frequency ranged from 71.35 to 86.45 and from 73.38 to 87.68, respectively. Lines HC and PB2 were the most closely related to the other, while BPB2 and CPB2 appeared to be more distant from each other. The between-line genetic distance based on both band sharing and band frequency revealed the similar trends as for Between-line genetic similarity. Based on BS and BF criteria, BPB2 and CPB2 as well as PB2 and UM1 lines can be merged to launch a new genetic group for further progress in biometrical objectives. A phylogenetic tree, derived using Nei's coefficient of similarity revealed the different pattern of genetic distance between lines.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제18권6호
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• pp.824-834
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• 1993

In cellular mobile communication systems, if the size of a cell is decreasing for economic utilization of frequency resources, frequent handovers may be requested because the time a mobile stays in a cell is decreasing. In general the measured parameters to decide handover including RSSI, BER, and the distance between mobile station and base station, are usually incorrect and handover decision using single parameter insufficient. Therefore, the better handover algorithm should take over the problems of this uncertain measurements, and make the decision more robust and flexible by the consideration of all those decision parameters at the same time. We propose a novel handover algorithm based the multicriteria decision making, in which those parameters are participated in the decision process using aggregation function in fuzzy set theory. As a simulation results, the overall decision making is more reliable and flexible than the conventional method using only one parameter, RSSI in terms of call force ratio, and handover request ratio.

• The Journal of the Korea Contents Association
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• 제12권8호
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• pp.388-398
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• 2012

In this study, Entropy method and PROMETHEE(Preference Ranking organization METHod for Enrichment Evaluations) which is one of the multi criteria decision making methods are applied to estimate the relative inundation risk ranking of the urban sewer systems. Then, the evaluation factors were selected considering two main items to estimate the inundation risk using Entropy and PROMETHEE. In the first item considering topographical and environmental factor, average elevation, average slope, width of area, population, density of conduit were selected as the detailed factors of first item which have influence of the overflow occurrence and damage scale in urban sewer system. And, the relative reliability of sewer network was considered as the second item which can quantify the inundation appearance. Then, the reliability is estimated considering the number of overflow nodes and overflow volume simultaneously. Therefore, the suggested inundation risk evaluation method can be used as the evaluation index for sewer networks and contribute to decision making for the sewer rehabilitation policy.

• Journal of the Korea Concrete Institute
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• 제24권4호
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• pp.423-433
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• 2012

The axial load on the concrete-filled steel tube (CFT) column produces confinement stress, which enhances strength of the core concrete. The amount of strength increase in concrete depends on the magnitude of produced confinement stress. From nonlinear analyses, the ultimate resisting capacity of the CFT columns subjected to axial loads was calculated. Nonlinear material properties such as Poisson's ratio and stress-strain relation were considered in the suggested model, and the maximum confining stress was obtained by multi axial yield criteria of the steel tube. This proposed model was verified by comparing the analytical results with experimental results. Then, regression analyses were conducted to predict the maximum confining stress according to D/t ratio and material properties without rigorous structural analysis. To ensure the validity of the suggested regression formula, various empirical formulas and Eurocode4 design code were compared.

• Journal of Korea Water Resources Association
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• 제47권7호
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• pp.573-585
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• 2014

In this study, we propose a consensus-building support system to engage various stakeholders, transparently disseminate information, ensure objective decision-making, and reflect the view of each stakeholder as a methodology or tool for resolving conflicts that may arise in the process of implementing water environment policies and plans. The system suggests ways to resolve issues by engaging all interested actors and not just a few influential groups of stakeholders imposing their solutions upon local users. The system provides an environment where stakeholders can find solutions to conflicts through their own efforts, mediating competing interests through the interactions such as negotiations and conciliation to reach a consensus. To verify the applicability of the proposed consensus-building support system, simulated role-playing albeit restricted was conducted on the case of the Hantangang Dam construction. The simulation validated that open discussions and negotiations with the local community or NGO by the government increased the efficacy of negotiations.

• Journal of the Korean Society for Precision Engineering
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• 제29권12호
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• pp.1376-1381
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• 2012

Optical devices are used extensively in the field of information network. Increasing demand for optical device, optical interconnection has been a important issue for commercialization. However many problems exist in the interconnection between optical device and optical fiber, and in the case of the multi-channel, problems of the optical alignment and optical array arise. For solving the alignment and array problem of optical device and the optical fiber, we fabricated fiber alignment and array by using imprint technology. Achieved higher precision of optical fiber alignment and array due to fabricating using imprint technology. The silicon stamp with different depth was fabricated using the conventional photolithography. Using the silicon stamp, a nickel stamp was fabricated by electroforming process. We conducted imprint process using the nickel stamp with different depth. The optical alignment and array by fabricating the patterns of optical device and fiber alignment and array using imprint process, and achieved higher precision of decreasing the dimensional error of the patterns by optimization of process. The fabricated optical interconnection of PLC device was measured 3.9 dB and 4.2 dB, lower than criteria specified by international standard.

• Journal of the Ergonomics Society of Korea
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• 제30권2호
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• pp.331-338
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• 2011

Objective: The present study developed a comprehensive usability testing and analysis framework based on a physical interface model of product and user and applied the proposed framework to usability testing of canister-type vacuum cleaner. Background: The development of a user-centered product design is important to satisfy customers who want to use the product with ease of use and to keep the manufacturer competitive in the market. Method: The proposed testing and analysis framework consists of (1) characterization of physical product-user interface, (2) preparation and administration of usability testing questionnaire, and (3) analysis and interpretation of usability testing results. A usability evaluation of five vacuum cleaners was planned and administered based on the proposed framework and its analysis produced detailed and overall usability testing results for various aspects such as tasks, usability criteria, and design components. Results: The testing results were further utilized to identify usability problems and preferred design features of the vacuum cleaners. Conclusion: The proposed usability testing and analysis framework was found effective to identify preferred features and problems of a product design in a systematic, holistic manner. Application: The proposed framework can be of effective use for practitioners of product design and development to obtain comprehensive, quantitative usability testing information in a systematic manner.

• Journal of the Ergonomics Society of Korea
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• 제32권2호
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• pp.167-177
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• 2013

Objective: This study aims to compare the usefulness of subjective measures which are comprised of existing methods like NASA-TLX, Bedford-scale and ZEIS and newly developed method like DALI in measuring drivers' mental workload in terms of validity, sensitivity and diagnosticity. Background: Nowadays, with the development of intelligent vehicle and HMI, mental workload of driver has become more and more important. For this reason, the studies on drivers' mental workload about driving situation and the use of information technology equipment such as mobile phones and navigations were conducted intensively. However, the studies on measuring drivers' mental workload were rarely conducted. Moreover, most of studies on comparison of subjective measures were used with performance based measure. However, performance based measures can cause distraction effect with subjective measures. Method: Participants (N=19) were engaged in a driving simulation experiment in 2 driving contexts (downtown driving and highway driving context). The experiment has 2 sessions according to driving contexts. The level of difficulties by driving contexts were adjusted according to existence of intersections, traffic signs and signals, billboards and the number of doublings. Moreover, as criteria of concurrent validity and sensitivity, the EEG data were recorded before and during the sessions. Results: The results indicated that all subjective methods were correlates with EEG in high-way driving. On the contrary to this, in downtown driving, all subjective methods were not correlates with EEG. In terms of sensitivity, multi-dimensional scales (NASA-TLX, DALI) were the only ones to identify differences between high way and downtown driving. Finally, in terms of diagnosticity, DALI was the most suitable method for evaluating drivers' mental workload in driving context. Conclusion: The DALI as newly developed method dedicated to evaluate driver's mental workload was superior in terms of sensitivity and diagnosticity. However, researchers should consider the characteristics of each subjective method synthetically according to research objective by selecting the method in subjective measures. Application: The results of this study could be applied to the intelligent vehicle and next generation of HMI design to decrease mental workload of driver and for the development of new subjective method in vehicle domain.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권1호
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• pp.84-93
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• 2001

An electromagnetic micro x-y stage for probe-based data storage (PDS) has been fabricated. The x-y stage consists of a silicon body inside which planar copper coils are embedded, a glass substrate bonded to the silicon body, and eight permanent magnets. The dimensions of flexures and copper coils were determined to yield $100{\;}\mu\textrm{m}$ in x and y directions under 50 mA of supplied current and to have 440 Hz of natural frequency. For the application to PDS devices, electromagnetic stage should have flat top surface for the prevention of its interference with multi-probe array, and have coils with low resistance for low power consumption. In order to satisfy these design criteria, conducting planar copper coils have been electroplated within silicon trenches which have high aspect ratio ($5{\;}\mu\textrm{m}$in width and $30{\;}\mu\textrm{m}$in depth). Silicon flexures with a height of $250{\;}\mu\textrm{m}$ were fabricated by using inductively coupled plasma reactive ion etching (ICP-RIE). The characteristics of a fabricated electromagnetic stage were measured by using laser doppler vibrometer (LDV) and dynamic signal analyzer (DSA). The DC gain was $0.16{\;}\mu\textrm{m}/mA$ and the maximum displacement was $42{\;}\mu\textrm{m}$ at a current of 180 mA. The measured natural frequency of the lowest mode was 325 Hz. Compared with the designed values, the lower natural frequency and DC gain of the fabricated device are due to the reverse-tapered ICP-RIE process and the incomplete assembly of the upper-sided permanent magnets for LDV measurements.