• Journal of the Korea Safety Management & Science
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• v.25 no.4
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• pp.131-140
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• 2023

This paper proposes an algorithm for the Unrelated Parallel Machine Scheduling Problem(UPMSP) without setup times, aiming to minimize total tardiness. As an NP-hard problem, the UPMSP is hard to get an optimal solution. Consequently, practical scenarios are solved by relying on operator's experiences or simple heuristic approaches. The proposed algorithm has adapted two methods: a policy network method, based on Transformer to compute the correlation between individual jobs and machines, and another method to train the network with a reinforcement learning algorithm based on the REINFORCE with Baseline algorithm. The proposed algorithm was evaluated on randomly generated problems and the results were compared with those obtained using CPLEX, as well as three scheduling algorithms. This paper confirms that the proposed algorithm outperforms the comparison algorithms, as evidenced by the test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.416-427
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• 1998

Unidirectional commingled-yarn-based carbon fiber(CF)/polyamide(PA) 6 composite was fabricated under molding pressures of 0.4, 0.6 and 1.0 MPa to study its flexural deformation and fracture behavior. Fiber/matrix interfacial bonding area became larger with an increase of molding pressure from 0.4 to 0.6 MPa. For molding pressures .geq. 0.6 MPa, good flexural performance of similar magnitudes was attained. For the fracture test, four kinds of notch direction were adopted : edgewise notches parallel (L) and transverse (T) to the major direction of fiber bundles, and flatwise notches parallel(ZL) and perpendicular(ZT) to this direction. Nominal bend strength for L and ZL specimens exhibited high sensitivity to notching. ZL specimens revealed the lowest values of the critical stress intensity factor $K_c$ which was slightly superior to those of unfilled PA6 matrix. Enlargement of the compression area for T specimens was analyzed by means of the rigidity reduction resulting from the fracture occurrence.

• Progress in Superconductivity and Cryogenics
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• v.14 no.3
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• pp.13-17
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• 2012

KEPCO Research Institute has been researching a Superconducting Fault Current Limiter (SFCL) which is considered one of solutions of fault current problems with Korea Institute of Machinery & Materials (KIMM) and Hanyang University since 2011. In this paper, we fabricated a current limiting module and conducted electrical short circuit tests for checking the validity of the transmission level SFCL design. Based on the short circuit characteristics of the second generation High Temperature Superconductor (HTS), we analyzed the short circuit characteristics of 3 parallel connected superconducting wires. The structure of the HTS wire is as follows: the stainless steel stabilizer of $100{\mu}m$ is laminated on the superconductor layer and under the substrate, both of which are electrically jointed with solder. We fabricated the current limiting module which has 40 series and 6 parallel connections and studied the short circuit characteristics of the module under various voltage levels.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.2
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• pp.29-37
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• 1997

A new algorithm and parallel architecture for high-speed complex number multiplication is presented, and a prototype chip based on the proposed approach is designed. By employing redundant binary (RB) arithmetic, an N-bit complex number multiplication is simplified to two RB multiplications (i.e., an addition of N RB partial products), which are responsible for real and imaginary parts, respectively. Also, and efficient RB encoding scheme proposed in this paper enables to generate RB partial products without additional hardware and delay overheads compared with binary partial product generation. The proposed approach leads to a highly parallel architecture with regularity and modularity. As a results, it results in much simpler realization and higher performance than the classical method based on real multipliers and adders. As a test vehicle, a prototype 8-b complex number multiplier core has been fabricated using $0.8\mu\textrm{m}$ CMOS technology. It contains 11,500 transistors on the area of about $1.05 \times 1.34 textrm{mm}^2$. The functional and speed test results show that it can safely operate with 200 MHz clock at $V_{DD}=2.5 V$, and consumes about 90mW.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.1
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• pp.66-70
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• 2001

This paper describes the design of a two-axis force sensor for robots finger. In detects the x-direction force Fx and y-direction force Fy simultaneously. In order to safely grasp an unknown object using the robots fingers, they should detect the force or gripping direction and the force of gravity direction, and perform the force control using the forces detected. Therefore, the robots hand should be made by the robots finger with tow-axis force sensor that can detect the x-direction force and y-direction force si-multaneously. Thus, in this paper, the two-axis force sensor for robots finger is designed using several parallel-plate beams. The equations to calculate the strain of the beams according to the force in order to design the sensing element of the force sensor are derived and these equations are used to design the aize of two-axis force sensor sensing element. The reliability of the derive equa-tions is verified buy performing a finite element analysis of the sensing element. The strain obtained through this process is compared to that obtained through the theory analysis and a characteristics test of the fabricated sensor. It reveals that the rated strains calculated from the derive equations make a good agreement with the results from the Finite Element Method analysis and from the character-istic test.

• Proceedings of the KIEE Conference
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• summer
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• pp.851-853
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• 2004

This paper deals with current distribution analysis of the windings of a superconducting transformer with BSCCO-2223 High Tc Superconducting (HTS) tapes. Current distribution of HTS windings wound in parallel is analyzed by electromagnetic field analysis of finite element method and verified by experiments. For the sake of uniform current distribution, windings must be transposed so to make the impedances of each strands same. The parallel HTS tapes were transposed between the pancakes via non-superconducting joints because it is hard to make transpositions inside the pancake windings. In order to measure current distribution, test windings are fabricated and experimented for both transposed and non-transposed windings. We compared test results with calculated ones.

• Structural Engineering and Mechanics
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• v.77 no.3
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• pp.369-381
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• 2021

The seismic responses of elevated tanks considering liquid-structure interaction are presented under horizontal earthquake. The scaled model tank is fabricated to study the dynamic responses of anchored tank and newly designed uplift tank with replaced dampers. The natural frequencies for structural mode are obtained by modal analysis. The dynamic responses of tanks are completed by finite element method, which are compared with the results from experiment. The displacement parallel and perpendicular to the excitation direction are both gained as well as structural acceleration. The strain of tank walls and the axial strain of columns are also obtained afterwards. The seismic responses of liquid storage tank can be calculated by the finite element model effectively and the results match well with the one measured by experiment. The aim is to provide a new type of tank system with vertical constraint relaxed which leads to lower stress level. With the liquid volume increasing, the structural fundamental frequency has a great reduction and the one of uplift tank are even smaller. Compared with anchored tank, the displacement of uplift tank is magnified, the strain for tank walls and columns parallel to excitation direction reduces obviously, while the one perpendicular to earthquake direction increases a lot, but the values are still small. The stress level of new tank seems to be more even due to uplift effect. The new type of tank can realize recoverable function by replacing dampers after earthquake.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.9
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• pp.572-577
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• 2000

This paper describes the test results of a single phase 3kVA high temperature superconducting power transformer. The tapes are made with Bi-2223 and have silver alloy as the matrix. Four double pancake windings are used. Among them two double pancake windings are connected in series for high voltage winding and the others are connected in parallel for low voltage winding. The rated voltage and current of primary winding and secondary winding are 220/110V. 13.7/27.3A. Fundamental characteristics are obtained through short circuit and no load test. The over load capability and characteristics are investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.715-718
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• 2001

Test in the development of vehicle consist of driving test and simulation test. The last one has many advantages. It can reduce time and cost during development, can overcome the spacial and environmental limitation, and can provides repeatabilities of similar experiments and various data. In these reason, the simulation test is used more for analysis and development of new vehicle. In this research the result of kinematic analysis on multi-axis simulator is compared with the simulated result using dynamic analysis program, ADAMS, and the maximum stress and strain are analyzed for the safety of link and specifications of optimal design using finite element method.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.2
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• pp.139-150
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• 1999

The ozone concentrations measured at the National Air Monitoring Stations between 1990 and 1995 were reviewed to detect any anomalies in the measurements. By screening the cases, in which variation of the ozone concentration from the previous measured value is greater than 75ppb, 125 station-days were identified as the test cases for the anomaly test. Historical and parallel consistencies of the measured concentrations were examined by plotting data for each test case. The detected anomalies can be classified into four categories; single outliers, anomalous variations during the startup period, baseline rises, and fluctuations in th diurnal variations. Anomalies were detected in as many as 80 cases among 125 test cases. Because of these anomalies, the number of hours exceeding 100ppb in the areas other than the Greater Seoul Area(GSA) could decrease from 157 to 107. Further studies for developing the methodology for eliminating the abnormal monitoring data are warranted for the data from the National Air Monitoring Stations are official to the both inside and outside of the country.