• Journal of the Korean Society for Heat Treatment
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• v.37 no.4
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• pp.182-187
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• 2024

To improve and control the mechanical properties of low alloy steel, the influence of quenching and tempering process conditions was investigated. In the case of quenching heat treatment, a comparison was made between the conventional method of heating to the austenite region followed by single quenching and a method involving double quenching, followed by high-temperature tempering. It was observed that specimens subjected to double quenching exhibited significantly finer tempered microstructures compared to those subjected to conventional quenching, resulting in noticeably higher hardness. Additionally, a study was conducted to investigate the variation in hardness with changes in tempering temperature and time after the same conventional quenching treatment. As expected, an increase in tempering temperature or time led to a decrease in hardness, and the correlation between hardness and the Hollomon-Jeffe Parameter was confirmed. It was also observed that during high-temperature tempering, the size of carbides significantly increased.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.2 no.1
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• pp.67-85
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• 1995

The purpose of this study was to determine the effects of rhythmic movement therapy for adaptation state in mastectomy patients. The quasi-experimental study was designed using nonequivalent control group pretest-posttest design within the framework of Laszarus & Folkman's stress-adaptation model. The subjects of the study were composed thirty-two mastectomy patients, of these fifteen were assigned to the experimental group and seventeen to the control group. Rhythmic movement therapy was carried out twice a week for thirty-five, minutes or forty minutes for six weeks period from August 22 to September 30 in 1994. Data was collected before and after the experimentation. Collected data was analyzed by mens of chi-square test, t-test, two-way ANOVA, Pearson's correlation coefficient with $SPSS/PC^+$. The results were summarized as follows : 1. Physical symptom score in the experimental group and control group was not significant difference. 2. Joint Movement Parameter in the experimental group and control group was significant difference. 3. Depression score in the experimental group and contrl group was significant difference. 4. Body image score in the experimental group and control group was significant difference. 5. Stress perception score in the experimental group and control group was significant difference. 6. Social adjustment score in the experimental group and control group was significant difference. 7. Each adaptational level in the experimental group and control group according to type of Health Locus of Control were partially significant difference. Depression score and social adjustment score between the experimental group and control group according to others Health Locus of control were significant difference. This data suggest that rhythmic movement therapy was more effective in the group of Others health Locus of Control. 8. Each adaptational level between the experimental group and control group according to amount of spouse support were not significant difference. 9. The significant positive correlation between physical symptom score and body image, between body image and social adjustment, were observed. The significant negative correlation between stress perception score and social adjustment, between depression and body image, between depression and social adjustment, were observed. This data suggest that the more physical symptom score increased, the more body image increased and the more body image, the more social adjustment. And then the more stress perception score decreased, the more social adjustment increasded and the more depression score, the more body image and social adjustment. Thus it is concluded that the rhythmic movement therapy was a useful nursing intervention for adaptation of mastectomy patients.

• Korean Journal of Poultry Science
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• v.29 no.2
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• pp.95-100
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• 2002

Two experiments were conducted to investigate the effect of taurine supplementation on lipid metabolism in laying hens. In experiment 1, 19-wk-old laying hens were given one of four taurine supplemented diets (0 (control), 0.4, 0.8, and 1.2% taurine) fur 10 weeks. Abdominal fat weight was lower in the 1.2% diet by 29.2% compared to the control. Serum concentrations of triacylglycerol and HDL-cholesterol were not different among the treatments. However, seam concentration of total cholesterol was higher by 22.4% in the 1.2% diet compared to the control. Concentration of triacylglycerol or total cholesterol in the liver were decreased by 26.1% or 26.4% and 28.2% or 26.4%, respectively in the 0.8% and 1.2% diets compared to the control. The concentration of HDL-cholesterol in liver was also lower by 33.9% in the 1.2% diet compared to the control. In experiment 2, 81-wk-old laying hens were allocated to one of three taurine supplemented diets (0 (control), 1 and 2% taurine) fur 6 weeks. Abdominal fat weight was lower by 25% in 1% taurine supplementation compared to the control. Serum concentrations of triacylglycerol, total cholesterol and HDL-cholesterol of hens fed with 1% diet were not different from those of control group. However, sew concentrations of triacylglycerol and total cholesterol were lower by 44.0% and 19.8%, respectively in the 2% diet compared to the control. Furthermore, serum concentration of HDL -cholesterol in the 2% diet was higher by 75% compared to the control. Concentrations of triacylglycerol and total cholesterol in the liver in the 2% diet were decreased in the 1% diet by 36.8 and 23%, respectively, but increased by 78.4% and 70%, respectively, compared to the control. The concentration of HDL-cholesterol in the liver was not different between the 1% diet and the control, but higher by 62.8% in the 2% diet compared to the control. These results indicated that taurine supplementation decreased the fat storage in abdominal cavity, which was accompanied by the changes in triacylglycerol and cholesterol metabolisms of laying hens.

• Journal of Animal Environmental Science
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• v.2 no.1
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• pp.41-52
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• 1996

This experiment was carried out to study the effect of sprinkler and fan cooling system on the physiological parameter, milk production and milk composition for Holstein cows in hot, humid climates. Thirty cows were assigned to one of two sections of open-sided loose barn. Water nozzles of sprinkler system were spaced in line at 1.2m intervals. Forced air was provided by 85cm diameter fans at rate of 3.4㎥/sec. The results obtained from these experiments are as follows: 1. There was no significant difference in meteorological data between control and fan + sprinkler cooling system(treatment group). 2. Skin temperature and rectal temperature of the treatment group were significantly lower than those of the control group (32.96 : 39.53$^{\circ}C$ vs 34.02 : 41.21$^{\circ}C$ respectively) (P<0.05). 3. Serum cortisol concentration of the treatment group(0.90$\mu\textrm{g}$/dL) was lower than that of control group(1.44$\mu\textrm{g}$/dL)(P<0.05). 4. Milk production of cows cooled with a sprinkler and fan cooling system was significantly higher than that of no cooling system (P<0.0l). 5. Lactose, protein and solid-not-fat content of milk were not changed by the treatments. Milk fat content of the control(3.23%) was low compared with the treatment group(3.38%). Somatic cell count was reduced by 26.63% in the treatment. The results indicate that a sprinkler and fan cooling systems can provide an effective means to relieve heat stress and enhance productivity of lactating Holstein cows during hot and humid summer season.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.1-9
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• 2015

To satisfy stricter $NO_X$ emission regulations for light- and heavy-duty diesel vehicles, a control algorithm needs to be developed based on a selective catalytic reaction (SCR) dynamics model for chemical reactions. This paper presents the development and validation of a SCR dynamics model through test rig experiments and MATLAB simulations. A nonlinear state space model is proposed based on the mass conservation law of chemical reactions in the SCR dynamics model. Experiments were performed on a test rig to evaluate the effects of the $NO_X$ and $NH_3$ concentrations, gas temperature, and space velocity on the $NO_X$ conversion efficiency for the urea-SCR system. The parameter values of the proposed SCR model were identified using the experimental datasets. Finally, a control-oriented model for an SCR system was developed and validated from the experimental data in a MATLAB simulation. The results of this study should contribute toward developing a closed-loop control strategy for $NO_X$ and $NH_3$ slip reduction in the urea-SCR system for an actual engine test bench.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.11
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• pp.589-598
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• 2007

In the group communication which has multiple data streams and various access privileges, it is necessary to provide group access control. The group members having the same access privilege are classified into one class, and the classes form a hierarchy based on the access relations. Then each class is assigned to a secret key. In the previous schemes, a single logical key graph is constructed from the hierarchy and each member always holds all secret keys of the classes he can access in the proactive manner. Thus, higher-privileged members hold more keys then lower-privileged members. However, if the hierarchy is large, each member manages too many keys and the size of multicast message in rekeying increases in proportion to the size of the hierarchy. Moreover, most of the members access a small portion of multiple data streams simultaneously. Therefore, it is redundant to receive rekeying message and update the keys in which he is not currently interested. In this paper, we present a new key management scheme that takes a reactive approach in which each member obtains the key of a data stream only when he wants to access the stream. Each member holds and updates only the key of the class he belongs. If he wants to get the key of other class, he derives it from his key and the public parameter. Proposed scheme considerable reduces the costs for rekeying, especially in the group where access relations are very complex and the hierarchy is large. Moreover, the scheme has another advantage that it easily reflects the change of access relations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.794-801
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• 2017

When a radial wheel is placed so as to partially overlap a conductive plate and rotated, a lift force is generated on the wheel, a thrust force along the edge, and a lateral force which tends to reduce the overlap region. When several of these wheels are combined, it is possible to realize a system in which the stability of the remaining axes is ensured, except in the traveling direction. To validate the overall characteristics of the multi-wheel system, we propose a transfer system levitated magnetically using radial electrodynamic wheels. The proposed system is floated and propelled by four wheels and arranged in a structure that allows the thrusts generated by the front and rear wheels to offset each other. The dynamic stability of the wheel and the effect of the pole number on the three-axial forces are analyzed by the finite element method. At this time, the thrust and levitation force are strongly coupled, and the only factor affecting them is the wheel rotation speed. Therefore, in order to control these two forces independently, we make use of the fact that the ratio of the thrust to the levitation force is proportional to the velocity and is independent of the size of the gap. The in-plane and out-of-plane motion control of the system is achieved by this control method and compared with the simulation results. The experimental results show that the coupled degrees of freedom can be effectively controlled by the wheel speed alone.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.437-444
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• 2020

This study was focused on the stabilization of surge motions of a moored vessel under irregular head seas. A two-point moored vessel shows strong non-linearity even in regular sea, owing to its inherent non-linear restoring force. A long-crested irregular wave is subjected to the vessel system, resulting in more complex nonlinear behavior of the displacement and velocities than in the case of regular waves. Sliding mode control (SMC) is implemented in the moored vessel to control both surge displacement and surge velocity. The SMC can provide a closed-loop system with performance and robustness against parameter uncertainties and disturbances; however, chattering is the main drawback for implementing SMC. The goal of minimizing the chattering and state convergence with accuracy is achieved using a quasi-sliding mode that approximates the discontinuous function via a continuous sigmoid function. Numerical simulations were conducted to validate the effectiveness of the proposed control algorithm.

• Progress in Medical Physics
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• v.26 no.4
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• pp.267-272
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• 2015

In this study, the reduction of dose and risk was evaluated from using automatic mA control in 4D CT scan of patients whose organ movement was considered for gated radiotherapy. The organ doses, CTDI, effective doses from 4D CT with and without using automatic mA control were evaluated using CT-Expo program for each 10 patients of liver and lung cancer, and the risk of exposure induced death and loss of life expectancy were evaluated using PCXMC program. It was founded that there were 26.8%, and 15.5% dose reduction in organ doses and CTDI for liver and lung cancer patients and 16.5% and 19.8% risk reduction in liver and lung cancer patients. The organ doses and effective doses were evaluated for the parameter of each patient used in CT scans, and risks considering age and gender could be evaluated. It was founded that there were 21.2% dose reduction and 18.2% risk reduction in 4D CT scan using AEC for liver and lung cancer patients.

• Journal of Periodontal and Implant Science
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• v.35 no.1
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• pp.87-98
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• 2005

The purpose of present study was to investigate the effects of physiologically active compound (SD62-122) from Phlomidis Radix on the cell cycle progression and its molecular mechanism in human gingival fibroblasts(HGFs). For this purpose, fibroblasts were isolated and cultured from excisioned gingiva during crown lengthening procedure in healthy adult. The following parameter were evaluated that there are cell number counting, MIT assay, cell cycle progression, western blot analysis. The cell number and MIT assay of primary cultured fibroblast was not increased at 2 days but significant increased compare to negative control at 3days(p<0.05). S phase was increased and G1 phase decreased in both $10^{-8}M$ and $10^{-9}M$ of SD62-122 in cell cycle analysis. The cell cycle regulation protein levels of Cyclin $D_1$, Cyclin E, cdk 2, cdk 4 and cdk 6 were increased compare to control in both $10^{-8}M$ and $10^{-9}M$ of SD62-122. The protein levels of p21 and p53 were decreased compare to control, but the level of pRb was not changed compare to control in $10^{-9}M$ of SD2-122. These results suggested that physiologically active compound (SD62-122) isolated from Phlomidis Radix increases the cell proliferation and cell cycle progression in HGFs, which is linked to increased cell cycle regulation protein levels of Cyclin $D_1$, Cyclin E, cdk 2, cdk 4 and cdk 6, and decreased the levels of p21, p53.