• Journal of the Korean Home Economics Association
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• v.23 no.4
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• pp.61-68
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• 1985

This study was conducted in a Korean airline catering operation where about 8, 000~10, 000 in flight meals per day were served. Time ad temperature observations were made in an actual airline catering operation to determine critical control points in mushroom and cheese omelet production, and to provide guidelines for the effective quality control programs of the airline catering operation. All data collection was replicated three times. Time and temperature data were collected by using standard instruments throughout the process sequence. Most phases of the food prodct flow were identified as critical control points. Holding phases of after cooking, and before and after reheating need a special attention, since foods were held at room temperature. Several guidelines were suggested for the effective quality control programs for the airline catering operation.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.69-76
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• 2007

The body of an excavator, one sort of the construction equipment, consists of mainframe part, track frame part, boom part and arm part. The all parts are manufactured in the body welding operation. The scheduling in the body welding operation of a construction equipment manufacturing is to take all the various constraints into consideration. The offset time, due date, daily capacity of operations, daily jig's capacity, precedence relation, outsourcing, alternative resource and all of the shop floor environment should be considered. An APS(Advanced Planning & Scheduling) system is a proper and efficient system in such circumstance. In this paper, we present an APS system, the optimal scheduling system for the construction equipment manufacturing specifically for the body welding operation, using ILOG Solver/Scheduler. ILOG Solver/Scheduler is a general purposed commercial software which supports to find a feasible or optimal solution using object oriented technique and constraints satisfaction programming, given constraints and objectives.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.51-57
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• 2016

Many kinds of telemetry should be monitored to check the state of spacecraft and it leads the time consumption. However, it is very important to define the status of satellite in short time because the contact number and time of low earth orbit satellite is limited. Also, on-board fault management should be prepared for non-contact operation because of the sever space environment. In this paper, on-board and ground autonomous operation method for the safety enhancement is described. Immediate fault detection and response is possible in ground by explicit anomaly detection through satellite event and error information. Also, satellite operation assistant system is proposed for ground autonomy that collect event sequence in accordance with related telemetry and recommend or execute an appropriate action for abnormal state. Critical parameter monitoring method with checking rate, mode and threshold is developed for on-board autonomous fault management. If the value exceeds the limit, pre-defined command sequence is executed.

• The Transactions of the Korea Information Processing Society
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• v.3 no.5
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• pp.1346-1353
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• 1996

In this paper, we propose a modeling method for the flip-flops and test generation algorithms to detect the faults in the sequential circuits using VHDL in the high-level design environment. RS, JK, D and T flip-flops are modeled using data flow types. The sequence of micro-operation which is the basic structure of a chip-level leads to a control point where varnishing occurs to one of two micro- operation sequence. In order to model the fault of one micro-operation(FMOP) that perturb another micro-operation effectively, the concept of goal trees and some heuristic rules are used. Given a faulty FMOP or fault of control point (FCON), a test pattern is generated by fault sensitization, path sensitization and determination of the imput combinations that will justify the path sensitization. The fault models are restricted to the data flow model in the ARCHITECTURE statement of VHDL. The proposed algorithm is implemented in the C language and its efficiency is confirmed by some examples.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.219-226
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• 2020

The container terminal operators established a re-marshalling plan to reduce the loading operation time and the release operation time. Re-marshalling is to rearrange the containers in the container yard to the advantageous position to shorten the working time using the spare time of the automated yard crane. This study assumed the automated container terminal with a perpendicular layout and deals with the inter-bay re-marshalling planning problem in a yard block. The inter-bay re-marshalling plan determines the container to be moved, the location to be relocated, and the sequence of relocation operations. This study presents a mixed integer programming model that simultaneously determines the storage location and the operation sequence while satisfying the spatial availability during the re-marshalling. Numerical experiments are conducted to understand re-marshalling operation using a beam search method.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1245-1254
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• 2018

The stability of a grid-connected system (GCS) has become a critical issue with the increasing utilization of renewable energy sources. Under grid faults, however, a grid-connected inverter cannot work efficiently by using only the traditional droop control. In addition, the unbalance factor of voltage/current at the common coupling point (PCC) may increase significantly. To ensure the stable operation of a GCS under grid faults, the capability to compensate for grid imbalance should be integrated. To solve the aforementioned problem, an improved voltage-type grid-connected control strategy is proposed in this study. A negative sequence conductance compensation loop based on a positive sequence power droop control is added to maintain PCC voltage balance and reduce grid current imbalance, thereby meeting PCC power quality requirements. Moreover, a stable analysis is presented based on the small signal model. Simulation and experimental results verify the aforementioned expectations, and consequently, the effectiveness of the proposed control scheme.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.130-133
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• 2009

The sequence of the propellant supply is very important for the reliable and safe operation of a LRE combustion test. So combustion performance tests were performed to find an optimum test sequence by changing supply time of propellants and purge gas in the moment of ignition and extinction. The liquid rocket engine consisted of a catalytic ignitor and six swirl-coaxial injectors which used hydrogen peroxide and kerosene. Conclusively, an optimum sequence was found for stable combustion in the moment of ignition and extinction.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1715-1717
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• 1997

This paper deals with the dead operation characteristics of the earth leakage circuit breaker(ELB) caused by impulse voltages. The surge protective devices for electronic circuit and AC power lines are becoming more widely used. It is possible to give rise to the malfunction of ELB due to the operation of surge protective devices, and the interruption of AC power lines brings about several disadvantages such as low reliability of electronic and informational systems, economical loss, and etc. The dead operation characteristics of the ELB from impulse voltages were measured under the conditions of KS C 4613 and the test circuit with a varistor. As a result, the peak current value of the zero-phase sequence circuit of the ELB is increased as the surge voltage and stray capacitance increase. All of the ELBs used in this work were satisfied with the lightning impulse dead operation test condition defined in KS C 4613. However one specimen only did not cause dead operation in the condition of the test circuit with a varistor. There is high possibility that a large portion of the ELBs connected with the AC power lines having the surge protective devices bring about the dead operation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.549-556
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• 2017

This study investigated the importance of social cognitive intervention and the cognitive rehabilitation intervention by comparing the difference and examining the relationship between neurological cognitive function and social cognitive function of stroke patients in the acute phase and chronic stroke before returning to the community. LOTCA, cartoon intention inference task, and social behavior sequence task were performed on 30 acute stroke inpatients and 30 chronic stroke patients from May 2015 to June 2016. A two sample t test was conducted to examine the differences between the groups. The Pearson's correlations test was performed to examine the correlation among the variables in each group. As a result, there were statistically significant differences between the neurological cognitive function and social cognitive function of acute stroke patients and chronic stroke patients who were undergoing rehabilitation training before returning to the community (p<0.05). A linear relationship was found between the thinking operation and social behavior sequence task in the acute stroke group (r=0.539, p<0.05). In the chronic stroke group, visual perception (r=0.530, p<0.05), visual motor organization (r=0.655, p<0.05) and thinking operation (r=0.534, p<0.05) were correlated with the cartoon intention inference task. In addition, the social behavior sequence task were correlated with visual organization (r=0.534, p<0.05) and thinking operation (r=0.764, p<0.05). As a result of multiple regression analysis, the neurological cognitive functions influencing the social cognitive function in the cartoon task was found to be the thinking operation (B = 0.431) in acute stroke patients and the thinking operation (B=0.272) and visuomotor organization (B = 0.218) in the case of chronic stroke. In addition, the results of the social behavior sequence task revealed the thinking operation (B=0.417) in the acute stroke patients, and thinking operation (B=0.267), visual motor organization(B=0.274) and visual perception(B=151) in chronic stroke patients to be significant. According to this result, there is a difference in the neurological and social cognitive levels between the two groups. Therefore, the social cognition is strongly related to the high level cognitive function as thinking operation of the neurological cognitive function. Therefore, in further research, it would be necessary to determine if there is a change in higher cognitive function in neurological cognitive function after applying a social cognition intervention program for stroke.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.2
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• pp.59-66
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• 2002

A vertical test stand based on launcher propulsion system was constructed and several tests for the determination of cyclogram were carried out. To make an accurate estimation, static and dynamic pressures were measured and analyzed. Especially, static pressure measurements using fast response sensors without extension tubes were used to determine operation sequence more evidently. The standard operation times of final valves were determined in cold flow tests with an engine head, and fire formation time in combustion chamber was checked in an ignition test with an ignitor only. On the basis of these tests, ignition sequence was established and combustion test cyclogram was finally determined. According to combustion test, test results were well matched with the determined cyclogram within 0.05 sec.