• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.42-50
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• 2001

In this paper, the effects of scale formation in engine water jacket upon the thermal durability of engine itself and its component parts were studied. To understand the effect of quality of water, a full load engine endurance test for 50 hours was carried out with not-treated underground water. The followings were found through the tested engine inspection after the endurance test; 1-2 mm thick scale formation in the engine water jacket, valve seat wear, piston top land scuffing, piston pin stick, and cylinder bore scuffing in siamese area. In order to understand the causes of above test results, the heat rejection rate to coolant, the metal surface temperature of combustion chamber, and the oil and exhaust gas temperatures were measured and analyzed. The scale formed in the engine water jacket played a role as thermal insulator. The scale formed in the engine reduced the heat rejection rate to coolant and it caused to increase the metal surface temperature. The reduced heat rejection rate to coolant increased the heat rejection rate to oil and exhaust gas and increased the oil and exhaust gas temperature. Also, the reasons of valve seat wear, piston top land scuffing and cylinder bore scuffing, and piston pin stick quantitatively analyzed in this paper.

• Journal of Korean Academy of Nursing
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• v.36 no.6
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• pp.992-1001
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• 2006

Purpose: This study was done to provide data for a nursing intervention to alleviate newborn pain clinically by investigating the effect of oral glucose. Methods: Subjects were newborns hospitalized in the nursery. Informed consent was obtained from parents of 60 newborns. A heel stick was carried out for a test on 3 groups; the experimental, placebo, and control group. The Neonatal infant pain scale(NIPS), respiration rate, heart rate, peripheral oxygen partial pressure($SpO_2$), and crying duration were measured to assess pain reaction. All neonatal behaviors were recorded on videotape. Results: There were significant differences in pain behavior during stimulus(F=4.195, p=.020), pain behavior immediately after blood-sampling (F=4.114, p=.021), and pain behavior 3 minutes after that (F=3.630, p=.033). However, there were no significant differences in heart rate, respiration rate, peripheral oxygen partial pressure or crying duration after the heel stick among the groups. Conclusions: Oral administration of glucose before a heel stick caused the reduction of neonatal pain behavior, which means that it has an effect of pain relief.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.462-468
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• 2017

KYP model is a pressure-based chemical kinetics that describes shock to detonation transition of energetic materials. In this research, the parameters of KYP model and JWL EOS for PETN-based explosive, namely PBXN-301, were determined. A series of unconfined rate stick tests and two dimensional hydrodynamic simulation were conducted to obtain the size effect behaviour of the explosive. As a result, it was confirmed that the parameters obtained from KYP modeling have more accuracy to predict the detonation velocities according to the inverse radius of PBXN-301 than the qualitatively obtained LLNL constitutive equations.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.12 no.3
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• pp.337-346
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• 2005

Purpose: The purpose of this study was to investigate the levels in student nurse of knowledge, compliance and risk factor recognition for needlestick injuries. Method: Nine hundred and thirty eight(938) student nurse from 3 universities and 3 junior colleges participated in this study. Completed questionnaires were collected between October and November 2004. They were analyzed by using the descriptive statistics and $x^2$-test, t-test with the SAS program, Results: There were no significant differences in the general characteristics of participants between the two groups-Needlestick Injury(NSI) group and non-Needle stick Injury(non-NSI) group. The scores for knowledge levels of treatment after needle stick injuries and the risk factor recognition level were significantly higher in the NSI group. The scores for performance level as to handling and using needles after needlestick injuries were significantly higher in the non-NSI group. Conclusion: It is necessary to develop a preventive program to decrease the needlestick injury rate among student nurse.

• International Journal of Highway Engineering
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• v.20 no.1
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• pp.107-115
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• 2018

PURPOSES : As the population of the mobility handicapped, who are classified as the disabled, the elderly, pregnant women, children, etc., has increased, the voices for guaranteeing their rights have been increasing as well. Thus, the design manuals for roads and sidewalks for the mobility handicapped were developed by the local government, such as the Ministry of Land, Transport, and Tourism, in Seoul City. However, according to the 2013 survey results of the Seoul Metropolitan City, the mobility handicapped still feel uncomfortable with the sidewalks, and particularly request for the improvement of the step and slope of the sidewalk curb. Therefore, in this study, we conducted an empirical experimental study to determine the slope of the sidewalk curb and height of the steps considering the mobility handicapped and analyzed whether there is a statistically significant difference. METHODS : The methodology of this study is an empirical experimental one. In the study, five non-disabled people, 10 wheelchair users, and 10 eye patch and stick users walked about 2-3 min on the sidewalk plates of the sloped type (0%, 5%, 6.3%, 8.3%) and stepped type (0 cm, 1 cm, 3 cm, 6 cm), and their human physiological responses, such as the skin temperature, volume of perspiration on forehead and chest, and heart rate, were measured and recorded. After combining the data, we conducted a nonparametric test, ANOVA, or t-test to determine whether there was a statistically significant difference according to each slope and step type. RESULTS : It was found that for the non-disabled, there was no significant difference in human physiological responses according to the slope and steps of the sidewalk. It can be said that the non-disabled do not feel much physiological discomfort while walking. In the case of the sloped sidewalk plate, the heart rate of the wheel chair users increased when the slope was 6.3%. In the case of the eye patch and stick users, the volume of perspiration on the chest increased at a slope of 5.0%. In general, it is judged that a sidewalk with a slope that is less than 5% does not cause a change in the physiological response. In the case of a stepped sidewalk plate, when 0 cm, 1 cm, and 3 cm were compared for wheelchair users, the amount of forehead perspiration increased from 1 cm. Meanwhile, in the case of the eye patch and stick users, when 0 cm and 6 cm were compared, the amount of perspiration on the forehead and chest as well as the heart rate all increased at 6 cm. Taken together, in the case of wheelchair users, a difference was shown when the height of the step of the sidewalk plate was 1 cm, suggesting that installing it at 0 cm does not cause any physiological discomfort. Moreover, in the case of the eye patch and stick users, when comparing only 0 cm and 6 cm, 0 cm was considered to be suitable, as there was a difference in physiological response at 6 cm. CONCLUSIONS : In this study, we set the human physiological responses such as chest skin temperature, amount of perspiration, and heart rate as evaluation items, and our study was considered to be a meaningful experiment that targeted wheelchair users as well as eye patch and stick users. The validity of the evaluation items was confirmed, as the results of human physiological responses were significant. As for the sidewalk design, according to the experiment result, it is considered that differential application should be implemented according to the type of mobility handicap, rather than uniformly applying a sidewalk step of 2 cm and sidewalk slope of 1/25, which are the current legal standards.

• KSTLE International Journal
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• v.3 no.1
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• pp.49-53
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• 2002

Inconel 690 for nuclear steam generator tube has more chromium than the conventionally used Inconel 600 in order to increase the corrosion resistance. TD evaluate the tribological characteristics under fretting condition the fretting tests as well as sliding tests were carried out in elevated temperature water environment. Fretting tests of the cross-cylinder type were done under various vibrating amplitudes and applied normal loads in order to measure the friction forces and wear volumes. Also, the conventional sliding tests of pin-en-disk type were carried out to compare the test results. In fretting, the friction was very sensitive to the load and the amplitude. The friction coefficient decreased with increasing load and decreasing amplitude. Also, the wear of Inconel 690 can be predictable using the work rate model. Depending on normal loads and vibrating amplitudes, distinctively different wear mechanisms and of ten drastically different wear rates can occur. It was fecund that the fretting wear coefficients in water were increased as increasing the temperature of water.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.263-268
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• 2000

The fretting damage of the contact between Zircaloy-4 and Inconel 600 have Investigated. A fretting wear tester was designed to be suitable for this fretting test. In this study, the number of cycles, slip amplitude and normal load were selected as main factors of fretting wear. As the result of this research the wear volume increased with the increase of loads, slip amplitudes and the number of cycles and was more affected by slip amplitudes rather than by load. According to SEM, stick, partial slip, gross slip were observed on the surface of both specimens and wavy worn surfaces as the typical fretting damage were also Investigated due to accumulation of plastic flow.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.511-518
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• 1997

The technique of fretting fatigue test was developed and fretting fatigue tests of A12024-T4 were conducted under several conditions. The newly developed calibration methods for measuring surface contact tractions showed good linearity and repeatability. The plate type specimen to which tow bridge type pads were attached and vision system was used to observe the crack behaviour. The oblieque cracks appeared in the early stage of crack growth and they became mode I cracks as they grow about 1 mm. The mode I transition points were found to be longer when surface tractions are higher or bulk stress is lower. Before the crack becomes mode I crack, 'well point' where crack grow about rate is minimum, was detected under every experimental condition. The crack behaviour was found to be affected by surface tractions, contact area, bulk stress. It was also found that partial slip and stick condition is most detrimental and the crack starts from the boundary of stick and slip. For gross slip crack started at the outside edge of pad. After crack mode transition, fretting fatigue cracks showed almost same behaviour of plain mode I fatigue cracks. Equivalent stress intensity factor was used to analyze the behaviour of fretting fatigue cracks and it was found that stress intensity factors can be applied to fretting fatigue cracks.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.318-326
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• 2021

This study aims to the effectiveness of physical examination using VR contents to solve problems such as the increase in chronic diseases and shortage of professional manpower in the health care field according to the aging and low birth rate, and to provide efficient healthcare. Therefore, this study implemented a one-stop VR content physical examination system by wearing HTC VIVE Pro VR and a stick controller. The system is from step 1 to step 5, and the final body age is determined and a simple solution is provided through five steps sequentially: color blind test, memory test, audiogram test, reaction speed test, and instantaneous cognitive ability test. In addition, for the one-stop VR content physical examination system developed by this study, as a result of verifying the user satisfaction for normal people who visited the health examination center and VR/AR clinical trial center of certified tertiary hospital in Daejeon, the overall satisfaction and the intention to reuse Was high, and according to gender, there was a significant difference in the 5-step test, and according to the age, there were significant differences in the 4-step test and the 5-step test.

• Tribology and Lubricants
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• v.30 no.3
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• pp.168-176
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• 2014

This paper presents an engine oil change warning algorithm based on the test results of a small dip-stick-gage-type engine-oil-deterioration-detection sensor, software to realize the algorithm and a display device to apply the software. The algorithm determines the engine oil deterioration condition from the rate of change in the dielectric constant based on the average measured capacitance at $80^{\circ}C$ after the engine stops. The rate of change in the dielectric constant at the time for oil change correlates with the time that one of recommended warning limits for engine oil physical properties such as TAN (Total Acid Number), TBN (Total Base Number) and viscosity is first reached. At this point, a warning signal for oil change appears on the display device like a smart-phone or individual display device. The frames of smartphone app have three stages. The user can directly input all of the thresholds into the frame of the smartphone app. The screen of the display device comprises one frame for each warning signature with the related message. The user can input the thresholds to the device through a USB cable connected to a personal computer.