• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.3
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• pp.212-223
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• 2007

18 Local exhaust ventilation systems in 10 melting companies located in an industrial complex were tested to know the status of maintenance. Test items were fan flowrates, fan static pressures, rotational speeds and differential pressures of bag filters. Only 22% of the tested fans has more than 80% flowrate efficiency. 44% of the fans has lower than 60% efficiency. The performance of the fans are not in a good status. For the fans with lower than 60% efficiency, the analysis shows that the lower flowrate might be caused by the degradation of fan performance. On the other hand, for the fan s with higher than 60% efficiency, the main cause of flowrate reduction might be too much pressure losses due to clogging of filter bags. The degradation of fans usually lead the reduction of hood capture efficiency, resulting in the increase of contaminant concentrations in workplace. To keep fans in good status, self inspections should be periodically conducted. This inspection should include the measurements of flowrate and pressures. The most important thing to be performed is the initial test of local exhaust ventilation system because the initial test data should be used to know the level of system degradation.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.745-758
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• 2022

As the unlimited natural source of a country, radio waves are widely being used in the daily life toward knowledge based information society. Therefore it is necessary to provide a long term policy of radio waves management policies based on market situation to cope with rapidly changing wireless technology and effective use of radio resources. Literary survey and analysis were accomplished for the rules and regulations in the radio station approval system and post-approval policies for mobile communication service. In conclusion, this study propose an blanket radio approval policy as well as self declaration of conformity(SDoC) of radio waves technical regulation and advanced radio inspection procedure. This study has significance in providing reference for introducing deregulation policy in the radio communication imdustry.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.134-141
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• 2011

There have been increased economic and societal demands to continuously monitor the integrity and long-term deterioration of civil infrastructures to ensure their safety and adequate performance throughout their life span. However, it is very difficult to continuously monitor the structural condition of the pipeline structures because those are placed underground and connected each other complexly, although pipeline structures are core underground infrastructures which transport primary sources. Moreover, damage can occur at several scales from micro-cracking to buckling or loose bolts in the pipeline structures. In this study, guided wave measurement can be achieved with a self-sensing circuit using a piezoelectric active sensor. In this self sensing system, a specific frequency-induced structural wavelet response is obtained from the self-sensed guided wave measurement. To classify the multiple types of structural damage, supervised learning-based statistical pattern recognition was implemented using the damage indices extracted from the guided wave features. Different types of structural damage artificially inflicted on a pipeline system were investigated to verify the effectiveness of the proposed SHM approach.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.10-19
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• 2016

The objective of this study is to investigate the self-healing properties of ternary blended cement(TBC) paste made with OPC, GGBFS and FA. The influence of OPC-GGBFS-FA on the self-healing ability of ternary blended cement paste was researched by ultrasonic pulse velocity(UPV) measurement. The TBC paste with GGBFS-FA replacement ratios of 20%, 40% and 60% were prepared having a constant water-cementitious materials ratios os 0.5. The research focuses on behavior after 28days(after loading). Four-point bending tests are used to pre-cracked the prismatic specimens at 28days. For specimens (uncracked and cracked) submerged in tap-water and sea-water until 60days. According to the experimental results, the TBC paste system has self-healing ability increased when the fraction of GGBFS increased. Because GGBFS and FA continues to hydrate after 28days, it is likely that hydrated products from GGBFS and FA may modify microstructures, seal these cracks. From these results, it is clear that the crack in all samples experience self-healing and that this occurs mostly in the first 30days of submerging. Futhermore, most of the healing for both specimens of submerged in sea-water and tap-water occurred during the first 30days. Sea-water submerged specimens healed cracks as fast as those in tap-water. Differences in healing effects of submerged in sea-water and tap-water may be attributed to the presence of specific sea-water ions. Therefore, self-healing effects considered age-effects was more strong effect occurred mostly in the first 30days, and then gradually weaken.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.504-510
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• 1991

SAMSUNG Electronics has developed a SCAR.A robot system, SM3, which is applicable to several assembly, inspection, and adjustment tasks. This robot system drives by AC servo motors has attained a .theta.1 and .theta.2 axis maximum composite speed of 5.4 m/sec, a repeatability of .+-.05 mm, and a cycle time of 1.2 sea. The robot controller based on three 8086 and one 8087 processors consists of the main controller, the joint position controller, and the motor controller. The robot controller has plentiful self-diagnosis and control capabilities, and can be interfaced to other external device. The robot language FARAL Is designed such that every task is easily programmed. In this paper, the main features of the body, controller, and FARAL of SM3 will be described. In particular, the control method designed for a stable and fast robot motion will be explained. Finally, the future development will be addressed.

• Korean journal of applied entomology
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• v.22 no.2 s.55
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• pp.106-129
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• 1983

An emphasized analysis and reviews on the progress of pesticide managements for the past 10 years through the statistics in Korea are summarized in this continued studies in connection with the fundmental aspects and direction of advanced pesticide industry and improved plantprotection policies for 1980's. Remarkable development and changes are observed in the plant species and varieties, plantation practices and production techniques as well as pest infestations and controls in the last decade, but no normal achievement and operations are recognised on the pesticide management and marketing system especially. Realistic plant protection adminstration and pesticide regulations in accordance to the industrial modernization and pest management advancement must be adjusted in accordance with national economic progress and desirable agricultural structure for 1980's. Special considerations are stated on the strengthening of research and inspection program for the quality products and control with the efficacy and safety use of pesticides. More serious attentions are noted on the over production and flooded stocks under struggled market demands and sales competitions with lethal financial difficulties by producers. Through the status analyzed for the last decade, the integrated past management and cooperative basic control pattern under positive self-forecasting system by farmers are also urged for the effective and economic pest control measures. The problems and solutions discussed here ell the advanced pesticide management as well as the cooperation on the self-ordered quality control and market managing systems in 1980's as it is a desired projection for the further improvement. Most of outstanding and necessary statistics and data in the past decade are also summarized here for references in connection with the previous report.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.14 no.1
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• pp.17-25
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• 1996

The development of still video CCD cameras has simplified dramatically the digital imaging process. Still video cameras have flexibility that allows digital image acquisition and on-board image storage without being connected to a computer. The objective of this paper is to evaluate the performance of digital close-range photogrammetric system using the still video camera for dimensional inspection and structural monitoring being required in various industries. Some sub-pixel measurement techniques, which is indispensable for digital image measurement, were suggested. The author carried out the self-calibration of a high resolution DCS420 still video camera and then test application of a structure. The self-calibrating bundle adjustments resulted in object space accuracies which exceed 1 :46,000. It is ascertained that this digital close-range photogrammetric system has high accuracy potential and task effectiveness for industrial applications.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.617-627
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• 2021

In the field of on-road motor vehicles, the level for autonomous driving technology is defined according to J3016, proposed by Society of Automotive Engineers (SAE) International. However, in the field of agricultural machinery, different standards are applied by country and manufacturer, without a standardized classification for autonomous driving technology which makes it difficult to clearly define and accurately evaluate the autonomous driving technology, for agricultural machinery. In this study, a method to classify the autonomy levels for autonomous agricultural machinery (ALAAM) is proposed by modifying the SAE International J3016 to better characterize various agricultural operations such as tillage, spraying and harvesting. The ALAAM was classified into 6 levels from 0 (manual) to 5 (full automation) depending on the status of operator and autonomous system interventions for each item related to the automation of agricultural tasks such as straight-curve path driving, path-implement operation, operation-environmental awareness, error response, and task area planning. The core of the ALAAM classification is based on the relative roles between the operator and autonomous system for the automation of agricultural machines. The proposed ALAAM is expected to promote the establishment of a standard to classify the autonomous driving levels of self-propelled agricultural machinery.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.238-244
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• 2022

Maintenance works of offshore wind turbines could take a longer time, which causes the reduction of their energy production efficiency, than those of onshore wind turbines owing to severe offshore environment. Subsequently, preventive maintenance measures are required to increase the production efficiency. Thus, we proposed a wheel-based Underwater Pole Climbing Robot (UPCR) platform, which was aimed at the periodic inspection and maintenance of the substructures of the offshore wind turbines, with three advantages: high speed, good mobility and low power consumption. In the proposed platform, a self-locking system using a gripper module was adopted for preventing slippery problem and a dual configuration was chosen for moving on a branched structure. As a result, the proposed robot was able to continuously climb, preserve it's position at the pole without consuming energy, and move from the pole to the other branched pole. The results of this research show that the UPCR has basic moving capabilities required for the underwater work for the substructures of the offshore wind turbines.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.126-133
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• 2017

This paper presents the shear capacities of hollow slab with plate and octagonal pillar type hollow sphere. Recently, the interest in precast hollow slab system for buildings is growing up according to the demand for high quality control and the increase in slab thickness. A hollow slab system is widely known as one of the effective slab system which can reduce self-weight of slab. However, hollow slabs are vulnerable to the deterioration in the shear strength due to the decrease of concrete at slab web which resists shear. Especially, in case of precast hollow slabs, it has joint surface between precast concrete slab modules along transverse axis of slab, and shear failure, that is caused by cracks at joints, has to be prevented. Therefore, in this study, shear capacity of the I-slab system is evaluated by 3-points-supported shear test along the longitudinal and transverse axis of slab specimen. Test results showed that I-slab had enough shear strength compared to theoretical shear strength even if it included the joint surfaces.