• Journal of Korean Society of Industrial and Systems Engineering
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• v.3 no.3
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• pp.35-39
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• 1980

Although the product line produces a large volume of goods in a relatively short time, once the product line is established there are numerous problems that arise in connection with this product line. One of these problems is the problem of balancing operations or stations in terms of equal times and in terms of the times required to meet the desered rate of production. The objective of line balancing is minimizing the idle time on the line for all combinations of work stations subject to certain restrictions. In general, there are two types of line-balancing situations : (1) assembly line balancing and (2) fabrication line balancing. Two approaches to the assembly line balancing problem have been used. The first assumes a filed cycle time and find the optimum number of work stations. The second approach to the assembly line balancing problem assumes the number of work stations to be fixed and systematically coverages on a solution which minimizes the total delay time by minimizing the cycle time. Here the cycle time is determined by the longest station time. In this paper, by using the second approach method, a general mathematical model, problem solutions, and computer program for the assembly line balancing problem is presented. Data used is obtained from the company which has been confronted with many problems arising in connection with their assembly line.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.331-335
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• 2010

Previous low-energy time synchronization methods have mainly focused on reducing the number of transmission or reception packets. However, this paper proposes a method that reduces the percentage of time a node has to be awake (the duty cycle), assuming that a periodic sleep-wake cycle is used to conserve energy. Based on our experience with actual WSN devices, a system model is proposed, and the potential performance of the proposed method, with different parameter values, is analyzed. To further demonstrate the feasibility of our method, experiments were conducted using nine WSN devices in a $3{\times}3$ grid network topology. The results show the average synchronization error is 107.57 $\mu{s}$ in duty cycle 5% and synchronization period 10 sec, and 130 $\mu{s}$ in duty cycle 2.5% and synchronization period 20 sec.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.254-256
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• 2007

In this paper, the effects of the reflow number in the mechanical reliability of flip chip solder joint was investigated by flip chip shear test and thermal shock test. For evaluation mechanical reliability of flip chip, We experiment that specimens were operated 3-times, 6-times, 9-times, 12-times under reflow Process. After shear test and thermal shock test, We measured max shear strength and coming first crack number of thermal cycle. And We observe fracture surface and cross section by using SEM(Scanning Electron Microscope) and optical scope. In the results, the more specimens were operated reflow process, the more decreased maximum shear strength and number of thermal cycle.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.611-616
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• 2001

Effects of high pressure and thermal pasteurization on the survival of microorganisms and quality changes of kochujang during 120 days of storage at 37$^{\circ}C$ were investigated. Viable cell counts were 1.43$\times$10$^{6}$ CFU/g in heat-treated, and 1.56$\times$10$^3$ CFU/g in pressure-treated, and decreased up to 3 log cycle, compared with 3.78$\times$10$^{6}$ CFU/g in the untreated kochujang. Viable cell counts decreased by the storage period at 37$^{\circ}C$. Viable cell counts decreased up to 2 log cycle from 3.78$\times$10$^{6}$ to 5.43$\times$10$^4$ CFU/g in the untreated kochujang, 4 log cycle from 1.43$\times$10$^{6}$ to 3.10$\times$10$^2$ CFU/g in heat-treated after 120 days of storage, while those in pressure-treated were not detected after 90 days from the initial stage of 1.56$\times$10$^3$ CFU/g. pH decreased significantly by the storage time. Titratable acidity increased significantly during storage, and pressure-treated kochujang showed lower values than heat-treated. Amino nitrogen content decreased significantly during storage, and pressure-treated kochujang showed higher values than heat-treated and lower values than the untreated. There were no significant changes in reducing sugar and ethanol content regardless of the treatment condition and the storage period. Hunter L, a and b values decreased significantly during storage. In the untreated kochujang, the changes in color accelerated compared with heat and pressure-treated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1701-1709
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• 1997

The diagnostic used to observe the early flame development was a fiber optic spark plug, which enabled measurement of the flame front arrival times on a cycle-to-cycle basis. The data obtained with this fiber optic spark plug were analyzed to obtain two parameters to describe the behavior of the flame kernel : an expansion speed and a convection velocity. In addition, synchronized cylinder pressure data were taken to compare with the fiber optic spark plug data on a cyclic basis. Heat release analysis was performed on the cylinder pressure data to obtain the mass burning profile of the charge for each cycle. There was a significant correlation observed in the initial flame duration and the kernel expansion speed with dwell angle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5389-5396
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• 2012

In this paper, an optimized residual data decoder architecture is proposed to improve the performance in H.264/AVC. The proposed architecture is an integrated architecture that combined parallel inverse transform architecture and parallel inverse quantization architecture with common operation units applied new inverse quantization equations. The equations without division operation can reduce execution time and quantity of operation for inverse quantization process. The common operation unit uses multiplier and left shifter for the equations. The inverse quantization architecture with four common operation units can reduce execution cycle of inverse quantization to one cycle. The inverse transform architecture consists of eight inverse transform operation units. Therefore, the architecture can reduce the execution cycle of inverse transform to one cycle. Because inverse quantization operation and inverse transform operation are concurrency, the execution cycle of inverse transform and inverse quantization operation for one $4{\times}4$ block is one cycle. The proposed architecture is synthesized using Magnachip 0.18um CMOS technology. The gate count and the critical path delay of the architecture are 21.9k and 5.5ns, respectively. The throughput of the architecture can achieve 2.89Gpixels/sec at the maximum clock frequency of 181MHz. As the result of measuring the performance of the proposed architecture using the extracted data from JM 9.4, the execution cycle of the proposed architecture is about 88.5% less than that of the existing designs.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.138-144
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• 1989

It has been very important in various industry fields to improve the fatigue strength characteristics of bearings such as bearing life, fatigue limit, etc., because such poor properties could result in shortening the machinery life as well as in decreasing the accuracy. However, no successful heat treatment criterion seems to be available at present. In this study, the effect of the $170^{\circ}C\times120min$ tempering cycles repeated after $380^{\circ}C\times80min$ oil quenching for $800^{\circ}C$ spheroidizing-annealed bearing steel (STB2) as base metal on the $120^{\circ}C$ high temperature rotary bending fatigue strength characteristics were investigated, including the effects on hardness, Charpy impact value and micro-structure, in order to seek for the best heat treatment condition finally. The important results obtained are as follows : 1) The optimal cycle of tempering so that the fatigue strength .sigma. could become the highest was the 4th cycle. And it is confirmed that this $\sigma_{F}$ is about 6 times more increased than that of base metal, and about 1.3 times more increased than the case of the 1 cycle tempered. 2) As a result of the investigation for the effects of tempering cycles on hardness, the hardness at the tempering number of 2 thru 5 cyles was not decreased severely ; only about 10% decrease from those of the quenched and 1 cycle tempered case. Such hardness is equivalent to $H_{R}$/C61-62 with no bad effect on anti-abrasion of bearing steel. 3) In the case of 2 thru 5 cycle tempering as well as 1 cycle tempering, the impact value was not so improved comparing with the case of quenching, but an increase of 5 to 10% could be expected at least. 4) It was experimentally confirmed that the control of the mechanical properties improvement such as fatigue strength and fatigue life for bearing steels could be possible by the number of tempering cycles.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.638-638
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• 1989

It has been very important in various industry fields to improve the fatigue strength characteristics of bearings such as bearing life, fatigue limit, etc., because such poor properties could result in shortening the machinery life as well as in decreasing the accuracy. However, no successful heat treatment criterion seems to be available at present. In this study, the effect of the $170^{\circ}C\times120min$ tempering cycles repeated after $380^{\circ}C\times80min$ oil quenching for $800^{\circ}C$ spheroidizing-annealed bearing steel (STB2) as base metal on the $120^{\circ}C$ high temperature rotary bending fatigue strength characteristics were investigated, including the effects on hardness, Charpy impact value and micro-structure, in order to seek for the best heat treatment condition finally. The important results obtained are as follows : 1) The optimal cycle of tempering so that the fatigue strength .sigma. could become the highest was the 4th cycle. And it is confirmed that this $\sigma_{F}$ is about 6 times more increased than that of base metal, and about 1.3 times more increased than the case of the 1 cycle tempered. 2) As a result of the investigation for the effects of tempering cycles on hardness, the hardness at the tempering number of 2 thru 5 cyles was not decreased severely ; only about 10% decrease from those of the quenched and 1 cycle tempered case. Such hardness is equivalent to $H_{R}$/C61-62 with no bad effect on anti-abrasion of bearing steel. 3) In the case of 2 thru 5 cycle tempering as well as 1 cycle tempering, the impact value was not so improved comparing with the case of quenching, but an increase of 5 to 10% could be expected at least. 4) It was experimentally confirmed that the control of the mechanical properties improvement such as fatigue strength and fatigue life for bearing steels could be possible by the number of tempering cycles.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.6
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• pp.1016-1024
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• 2000

The study was conducted to develop a rapid method for the detection of Listeria monocytogenes in foods via polymerase chain reaction (PCR) technique using hemolysin gene (hlyA) primers. Specificity and sensitivity of PCR, optimal conditions for PCR and application of hlyA gene primers for the detection of L. monocytogenes from milk and beef were investigeted. Each of the 20 L. monocytogenes strains gave a single 713 bp band, but other Listeria sup. and other bacteria did not show any bands. As few as 1 pg of L. monocytogenes DNA or 2.4$\times$10$^4$L. monocytogenes cells could be detected with hlyA gene primers. PCR product was most improved at 20~30 cycle in terms of removal of tailing and sensitivity. Also, the sensitivity was significantly improved by the further 10~15 cycle after 20 cycle PCR amplication. Milk (10 mL) and beef (10 g) samples were inoculated with L. monocytogenes at the concentrations ranging from 0 to 10$^{7}$ CFU/mL or g to determine the best sensitivity of PCR for the rapid detection of L. monocytogenes. PCR assay could detect 2 cells in milk with repeating PCR amplication and 2.6$\times$10$^2$cells in beef sample after 24 hr enrichment growth at 35$^{\circ}C$ in LEB.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.2
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• pp.77-83
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• 2011

In this paper, we present the design procedure of the synchronizer and the demodulator of a 13.56MHz RFID PJM tag, which was standardized in ISO 18000-3 mode 3. We optimize the algorithms in order to minimize the number of registers and implement them based on international standard. The designed module is simulated by Modelsim and FPGA. The synchronizer is composed of 3 correlators that is implemented by 1,024(16bit ${\times}$ 64cycle) registers. The demodulator is composed of 2 correlators that is implemented by 128(2bit ${\times}$ 64cycle) registers. The simulation performed with the demodulator integrated with the synchronizer shows that it works at about 87% success rate with the test data of SNR -2dB and 100% with those of SNR 4dB.