• Journal of Korean Institute of Industrial Engineers
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• v.42 no.2
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• pp.122-128
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• 2016

The purpose of this study is to improve the firing elevation driving method for towed howitzer to prevent the musculoskeletal disorders. To adjust the firing elevation, it is required to rotate the hand wheel and this work has been done manually in the firing test range as the same method as field artillery troops. In the firing test range, the motor-driven firing elevation adjustment device was developed to improve the working efficiency and safety. These were compared by using posture classification scheme of RULA and REBA. It was measured elapsed time to investigate the improved operational efficiency. The optimal posture of upper body to operate the hand wheel for field artillery troops was proposed.

• Journal of the Korea Safety Management & Science
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• v.6 no.2
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• pp.23-33
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• 2004

Domestic city gas is supplying in an about 10 million household on present 34 city gas companies because is begun to supply regularly after two 1980 years middle. But, result that focus on city gas supply spread and stable supply for supply area and neglects about safety problem, hundreds casualties such as Ahyun explosion accident and Deagu city gas explosion accident were reached in situation that occurred large size calamity occurs it is dizzliness. In the case of advanced nation, can see that accomplish system and progress that in technology after experience major accident. Therefore, grasp problem investigating safety actual conditions for city gas institution and study about solvable plan is required this. Also, must guide reform and level elevation of a domestic company safety technology through induction and development of safety technology that is suitable in supply, domestic real condition etc. Must help in power positivity that is full text executing high-quality safety education about step High firing mechanism safety technology than present safety education.

• Proceedings of the Safety Management and Science Conference
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• 2004.05a
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• pp.5-8
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• 2004

Domestic city gas is supplying in an about 10 million household on present 34 city gas companies because is begun to supply regularly after two 1980 years middle. But, result that focus on city gas supply spread and stable supply for supply area and neglects about safety problem, hundreds casualties such as Ahyun explosion accident and Deagu city gas explosion accident were reached in situation that occurred large size calamity occurs it is dizzliness. In the case of advanced nation, can see that accomplish system and progress that in technology after experience major accident. Therefore, grasp problem investigating safety actual conditions for city gas institution and study about solvable plan is required this. Also, must guide reform and level elevation of a domestic company safety technology through induction and development of safety technology that is suitable in supply, domestic real condition etc. Must help in power positivity that is full text executing high-quality safety education about step High firing mechanism safety technology than present safety education.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.6
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• pp.247-251
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• 2007

Changes of single unit activity of CA1 hippocampus region were investigated in anesthetized Mongolian gerbils for six days following transient ischemia. Ischemia was produced immediately before the implantation of micro-wire recording electrodes. In control animals receiving pseudo-ischemic surgery, neither spontaneous neuronal activities ($5.70{\pm}0.4Hz$) nor the number of recorded neurons per animal changed significantly for six days. Correlative firings among simultaneously recorded neurons were weak (correlation coefficient > 0.6) in the control animals. Animals subjected to ischemia exhibited a significant elevation of neural firing at post-ischemic 12 hr ($9.95{\pm}0.9Hz$) and day 1 ($8.48{\pm}0.8Hz$), but a significant depression of activity at post-ischemic day 6 ($1.84{\pm}0.3Hz$) when compared to the activities of non-ischemic control animal. Ischemia significantly (correlation coefficient > 0.6) increased correlative firings among simultaneously recorded neurons, which were prominent especially during post-ischemic days 1, 2 and 6. Although the numbers of spontaneously active neurons recorded from control group varied within normal range during the experimental period, those from ischemic group changed in post-ischemic time-dependent manner. Temporal changes of the number of cells recorded per animal between control group and ischemic group were also significantly different (p = 0.0084, t = 3.271, df = 10). Cresyl violet staining indicated significant loss of CA1 cells at post-ischemic day 7. Overall, we showed post-ischemic time-dependent, differential changes of three characteristics, including spontaneous activity, network relationship and excitability of CA1 cells, suggesting sustained neural functions. Thus, histological observation of CA1 cell death till post-ischemic day 7 may not represent actual neuronal death.

• Archives of design research
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• v.21
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• pp.185-194
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• 1997

Although the wall tile, which is the finishing material, has been used in many parts of the living space, there has been no attention to the process of research, production and marketing. Owing to the elevation of living tastes and the betterment of housing is causing a lot of interest and care about the finishing material in the inner part of housing, the interest on the wall tile has been remarkably increased. Even to the designers who are specializing in design, the wall tile industrial field has considered as only a ceramics, therefore it has not been indifferent to. With the background of the above, being conducted researches for causing interest and understanding in the wall tile industries with the various approach focusing on the importance of design, the desirable roles and direction of design in the \vall the tile field, this study shows the development and desirable future of the wall tile industries in our country.

• The Korean Journal of Physiology
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• v.18 no.1
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• pp.19-35
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• 1984

Since the first report of Drury and $Szent-Gy{\ddot{o}}rgyi$ in 1929, the inhibitory influences of adenosine on the heart have repeatedly been described by many investigators. These studies have shown that adenosine and adenine nucleotides have overall depressant effects, similar to those of acetylcholine. Heart beats become slow and weak. It is also well known that adenosine is a potent endogenous coronary vasodilator. Many investigations on the working mechanisms of adenosine have been focused mainly on the effects of the coronary blood flow. However, the cellular mechanisms underlying the inhibitory action of adenosine on sinus node are not well understood yet. Thus, this study was undertaken to examine the behavior of rabbit SA node under influence of adenosine. In these series of experiments three kinds of preparations were used: whole atrial pair, left atrial strip, and isolated SA node preparations. The electrical activity of SA node was recorded with conventional glass microelectrodes 30 to 50 $M{\Omega}$. The preparations were superfused with bicarbonate-buffered Tyrode solution of pH 7.35 and aerated with a gas mixture of $3%\;CO_2-97%\;O_2$ at $35^{\circ}C$. In whole atrial pair, adenosine suppressed sinoatrial rhythm in a dose-dependent manner. Effect of adenosine on atrial rate appeared at the concentration of $10^{-5}M$ and was enhanced in parallel with the increase in adenosine concentration. Inhibitory action of adenosine on pacemaker activity was more prominent in the preparation pretreated with norepinephrine, which can steepen the slope of pacemaker potential by increasing permeability of $Ca^{+2}$. Calcium ions in perfusate slowly produced a marked change in sinoatrial rhythm. Elevation of the calcium concentration from 0.3 to 8 mM increased the atrial rate from 132 to 174 beats/min, but over 10 mM $Ca^{+2}$ decreased. The inhibitory effect of adenosine on sinoatrial rhythm developed very rapidly. Atrial rate was recovered promptly from the adenosine-induced suppression by the addition of norepinephrine, but extra $Ca^{+2}$ was less suitable to restore the suppression of atrial rate. Adenosine suppressed also atrial contractility in the same dosage range that restricted pacemaker activity, even in the reserpinized preparation. In isolated SA node preparation, spontaneous firing rate of SA node at $35^{\circ}C$(mean{\pm}SEM, n=16) was $154{\pm}3.3\;beats/min. The parameters of action potentials were: maximum diastolic potential(MDP), $-73{\pm}1.7\;mV: overshoot(OS), $9{\pm}1.4\;mV: slope of pacemaker potential(SPP), $94{\pm}3.0\;mV/sec. Adenosine suppressed the firing rate of SA node in a dose-dependent manner. This inhibitory effect appeared at the concentration of $10^{-6}M$ and was in parallel with the increase in adenosine concentration. Changes in action potential by adenosine were dose-dependent increase of MDP and decrease of SPP until $10^{-4}M$. Above this concentration, however, the amplitude of action potential decreased markedly due to the simultaneous decrease of both MDP and OS. All these effects of adenosine were not affected by pretreatment of atropine and propranolol. Lowering extra $Ca^{2+}$ irom 2 mM to 0.3 mM resulted in a marked decrease of OS and SPP, but almost no change of MDP. However, increase of perfusate $Ca^{2+}$ from 2 mM to 6 or 8 mM produced a prominent decrease of MDP and a slight increase of OS and SPP. Dipyridamole(DPM), which is known to block the adenosine transport across the cell membrane, definately potentiated the action of adenosine. The results of this experiment suggest that adenosine suppressed pacemaker activity and atrial contractility simultaneously and directly, by decreasing $Ca^{2+}-permeability$ of nodal and atrial cell membranes.