• Journal of Ocean Engineering and Technology
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• v.21 no.2 s.75
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• pp.67-74
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• 2007

Maritime and Ocean Engineering Research Institute (MOERI), a branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) named ISiMI (Integrated Submergible for Intelligent Mission Implementation). ISiMI is an AUV platform to satisfy the various needs of experimental test required for development of challenging technologies newly investigated in the field of underwater robot; control and navigational algorithms and software architectures. The main design goal of ISiMI AUV is downsizing which will reduce substantially the operating cost compared to other vehicles previously developed in KORDI such as VORAM or DUSAUV. As a result of design and manufacturing process, ISiMI is implemented to be 1.2 m in length, 0.17 m in diameter and weigh 20 kg in air. A series of tank test is conducted to verify the basic functions of ISiMI in the Ocean Engineering Basin of MOERI, which includes manual control with R/F link, auto depth, auto heading control and a final approach control for underwater docking. This paper describes the implementation of ISiMI system and the experimental results to verify the function of ISiMI as a test-bed AUV platform.

• Ocean and Polar Research
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• v.33 no.1
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• pp.69-76
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• 2011

A test miner named MineRo was constructed for the purpose of shallow water test of mining performance. In June of 2009, the performance test was conducted in depth of 100 m, 5 km away from Hupo-port (Korean East Sea), to assess if the developed system is able to collect and lift manganese nodules from seafloor. In August of 2010, in-situ test of automatic path tracking control of MineRo was performed in depth of 120 m at the same site. For path tracking control, a localization algorithm determining MineRo's position on seabed is prerequisite. This study proposes an improved underwater navigation algorithm through estimation of MineRo's kinematic parameters. In general, the kinematic parameters such as track slips and slip angle are indirectly calculated using the position data from USBL (Ultra-Short Base Line) system and heading data from gyro sensors. However, the obtained data values are likely to be different from the real values, primarily due to the random noise of position data. The aim of this study is to enhance the reliability of the algorithm by measuring kinematic parameters, track slips and slip angle.

• Journal of the Korean institute of surface engineering
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• v.47 no.1
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• pp.13-19
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• 2014

The various surface treated conditions of Fe-3.0%Ni-0.7%Cr-1.4%Mn-X steel such as as-received, ion nitriding, DLC coated, DLC coated after nitriding for 3 hrs and 6 hrs were investigated to evaluate the beneficial effect for plastic mold steel. Micro Vickers hardness tester was used to estimate nitriding depth from the hardness profile and to measure hardness on the surface. Elastic modulus and residual stress were measured by a nanoindentator. Scratch test and SP (small ball punch test) were utilized to assess the adhesive strength of DLC coating. The depth of nitriding layer was measured as $50{\mu}m$ for the condition of 3 hrs nitriding and $90{\mu}m$ for that of 6 hrs nitriding. Hardness, elastic modulus, residual stress of DLC coating were 20.37 GPa, 162.78 GPa and -1456 MPa respectively. Residual stress on the surface of DLC coating after nitriding could increase to -3914 MPa by introducing nitriding before DLC coating. During the 'Ball-On-Disc' test ${\gamma}^{\prime}$ particles pulled out from the surface of nitrized layer tend to enhance abrasive wear mode since the fraction of ${\gamma}^{\prime}$ (Fe4N) in ion-nitrized layer is known to increases with nitriding time. Thus the specific wear rate of the nitriding layer increased. Comparing with nitriding the specific wear rate in work piece disc as well as ball decreased prominently in DLC coating due to the remarkable reduction in friction coefficient.

• Journal of the Korean institute of surface engineering
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• v.49 no.5
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• pp.423-430
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• 2016

In this study, we investigated the corrosion damage characteristics of steel for offshore wind turbine tower substructure using an accelerated electrochemical test. The galvanostatic corrosion test method was employed with a conventional 3 electrode cell in natural sea water, and the steel specimen was served as a working electrode to induce corrosion in an accelerated manner. Surface and cross-sectional image of the damaged area were obtained by optical microscope and scanning electron microscope. The weight of the specimens was measured to determine the gravimetric change before and after corrosion test. The result revealed that the steel tended to suffer uniform corrosion rather than localized corrosion due to active dissolution reaction under the constant current regime. With increasing galvanostatic current density, the damage depth and surface roughness of surface was increased, showing approximately 25 times difference in damage depth between the lowest current density ($1mA/cm^2$) and the highest current density ($200mA/cm^2$). The gravimetric observation showed that the weight loss was proportionally increased with increment of current density that has 75 times different according by experimental conditions. Consequently, uniform corrosion of the steel specimen was conveniently induced by the electrochemically accelerated corrosion technique, and it was possible to control the extent of the corrosion damage by varying the current density.

• The Korean Journal of Emergency Medical Services
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• v.15 no.1
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• pp.37-46
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• 2011

Purpose : This study is equivalence experiment performed to test practice effects between experimental group from both left and right direction of mannequin and control group having practice from only right direction in cardiopulmonary resuscitation education. Methods : Subject of the research were total 71 elementary and middle school teachers in J province who had not experience to have cardiopulmonary resuscitation. They were divided into experimental group of 35 participants who practiced cardiopulmonary resuscitation from both right and left direction of mannequin on Dec. 27, 2009 and control group of 36 participants who performed cardiopulmonary resuscitation from only right direction of mannequin on Dec. 28, 2009. Collected data were analyzed by SPSS/PC+(version 14.0). Results : 1. There was no statistically significant difference by sex among general characteristics of the subjects. 2. According to the quality of chest compression performed from the right direction of mannequin, experimental group showed better results in proper depth (time), insufficient depth (time), too lowered compression position (time) and inexact position (time) than control group(p<.05). In the quality of chest compression from the left side of mannequin, experimental group performed better results in proper depth (time), insufficient depth (time), inexact compression position (time) and mean chest compression depth(mm) than control group(p<.05) and also in more left-centered compression position (time) than control group(p<.001). 3. The quality of chest compression by experimental group, the right side of mannequin was superior in proper depth (time) to the left side of mannequin (p<.001) and showed better results in insufficient depth (time) and chest compression/recoil rate (p<.05). According to the quality of chest compression by control group, the right side of mannequin showed superior results in proper depth (time), insufficient depth (time), too left-centered compression position (time) and mean chest compression depth (mm) (p<.05) to the left side of mannequin. Conclusion : The group having practice from both right and left sides of mannequin was superior in the quality of chest compression to the group having practice from only right side of mannequin. How to practice cardiopulmonary resuscitation from both right and left sides of mannequin can be recommended and practice from left side of mannequin is also useful.

• Magazine of the Korean Society of Agricultural Engineers
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• v.25 no.2
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• pp.35-41
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• 1983

This research is mainly to deal with the effects of submergence treatment on the grain yields of two rice plants, local variety, "Akibare" and Tongil line variety, "Milyang 23". The results obtained are summarized as follows. 1. According to the rice products of each plot the grain yield index was smallest in the plot treated at the early heading stage. The index of the next order became smaller in order of late flowering stage, late reduction division stage, milk ripe stage and dough ripe stage etc. The submerged stage at which the damages were smallest was tillering stage. Under the condition of two thirds or one third submerged depth of plant height, few differences in the grain yield index between Milyang 23 and Akibare was found, but except rooting stage, the damages of milyang 23 by whole submergence during growing period were mostly greater than those of Akibare. Especially the grain yield index of early heading stage at which the damages by whole submergence was most serious showed 45 percentage for one day submergence, 31 percentage for 3 days and 0.7 percentage for 7 days in Akibare plots, and 26.7% percentage for one day submergence, 7.9 percentage for 3 days and none for 7 days in Milyang 23 plots. 2. All the factors such as submerged stage, submerged depth and submerged period in this experimental test were highly recognized significance. The factors of the submerged depth and duration influenced on greater damages than the others. According to the difference in grain yield between plots, the larger the submerged depth and duration were, the larger the significant difference appeared. And between the treated levels at other submerged stages except both early tillering stage and most active tillering stage, the significance in the differences in grain yield was recognized, while only the submergence at early heading stage showed the most serious damages. 3. The decreased rate of grain yield for one day submergence at early heading stage indicated that in case of whole submergence of plant height it was 73 percentage in Milyang 23 plot and 55 percentage in Akibare plot, and in the event of two thirds and one third submergences of it, 20 percentage and 10 percentage in both Mulyang 23 and Akibare plots respectively. Therefore, the current criteria for planning project that restricted allowable submergence duration of more than 30cm submerged depth to 24 hours, should be amended not to exceed the submerged depth of 60cm when the duration of more than allowable submerged depth of 30cm will be limited to 24 hours, or within the limits of 12 hour submerged duration for locai variety and of less than 12 hour duration for Tong-illine variety as long as possible in case that submerged depth will be allowed to more than 60cm depth.ore than 60cm depth.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.405-410
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• 2001

To investigate factors influencing the effective width of. SRC column-steel beam joint resisting the moment as strut, six specimens are designed and tested. Parameters in the test are column width, beam height and horizontal tie within beam depth. From the test, using either wide column width or ties, strength and stiffness of joint were developed. The lower beam height the specimens showed the lower moment.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.174-179
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• 2003

Non-destructive test on the size and depth of cracks has been required for the safety evaluation of structures. Ultrasonic method based on laser techniques is one of the most popular non-destructive methods which overwhelm PZT based tests. In the present paper, ultrasonic was generated by high powered Q switching Nd:YAG pulse laser. Experiments were carried out using Fabry-Perot interferometer which was intensively discussed in the present study.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.12
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• pp.457-463
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• 1985

This paper studies on the tracking phenamena by the IEC recommended method with various polymeric insulating materials which are used in industrial fields. Under the same experimental condition, according to the materials it is observed that there are the type of tracking breakdown and the type of tracking erosion. In the tracking breakdown type materials, the tracking breakdown is occurred at a small number of drops increasing of test voltage and solution density. In the tracking erosion type materials, the erosion depth is saturated or proportioned as increasing of test voltage and solution density.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.135-146
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• 2003

Uphole test is a seismic field test using receivers on ground surface and a source in depth. In this paper, the uphole test using SPT(standard penetration test) which is economical and reliable for obtaining shear wave velocity profile was introduced. In the proposed uphole test, SPT sampler which is common in site investigation, was used as a source and several 1Hz geophones in line were used as receivers. Test procedures in field and interpretation methods for obtaining interval times and for determining shear wave velocity profile considering refracted ray path were introduced. Finally, uphole test was performed at three sites, and the applicability of the proposed uphole test was verified by comparing wave velocity profiles determined by the uphole test with the profiles determined by downhole test, SASW test and SPT-N values.