• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.5
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• pp.321-328
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• 2015

In recent years, there has been an increasing demand to apply the new IACS(International Association of Classification Societies) standards for ice and polar-classed ships. For ice-class vessel propulsion system, the ice impact torque design criterion is defined as a periodic harmonic function in relation to the number of the propeller blades. However, irregular or transient ice impact torque is assumed to occur likely in actual circumstances rather than these periodic loadings. In this paper, the reliability and torsional vibration characteristics of a comparatively large six-cylinder marine diesel engine for propulsion shafting system was examined and reviewed in accordance with current regulations. In this particular, the transient ice impact torque and excessive vibratory torque originating from diesel engine were interpreted and the resonant points identified through theoretical analysis. Several floating ice impacts were carried out to evaluate torque responses using the calculation method of classification rule requirement. The Newmark method was used for the transient response analysis of the whole system.

• Journal of Animal Environmental Science
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• v.8 no.2
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• pp.99-106
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• 2002

This study was conducted to improve utilization efficiency of slurry and choose a suitable type of tractor power which can be attached by manure spreader in the paddy field. In the paddy field, the pulling force for the spreader was measured by using a measurement system installed between tractors with and without the spreader. The soil moisture contents at the 0${\sim}$10cm and 10${\sim}$20cm depth of test soil(SiCL) were 28.45% d.b. and 23.47% d.b., respectively in average while Cone Index at l0cm and 15cm depth were 14.5kPa and 16.2kPa, respectively. It was impossible to measure the soil moisture contents and Cone Index below 20cm depth of the soil because the hardness of the soil increased greatly. Thereafter, hard pan of the sampled soil was found at 15${\sim}$20cm depth. While the required power only for the dragged tractor was found to be 3.44kW in the test field, the required pulling powers of tractor considering the pumping were 8.48${\sim}$12.48kW, 12.19${\sim}$16.19kW, 16.96${\sim}$20.96kW, respectively for 2 tons, 3 tons, and 4 tons of tank capacity. As the tank capacity increased, the sinkage of soil were also increased to 7cm, l0cm, and 12cm, respectively for the tractors with 2 tons, 3 tons and 4 tons of tank capacity. Considering about 60% of pulling efficiency of tractor, a tractor which had lower than 25.74kW of pulling power was suitable to pull the spreader and spread the slurry simultaneously for manure spreader with 2 tons of tank capacity. 29.42kW${\sim}$36.78kW of pulling power was found to be optimum for the tractor with 3 tons of tank capacity while over 40.45kW for 4 tons of tank capacity.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.105-114
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• 2020

In this paper, we address security issues in 5G non-public networks for industrial applications. In contrast to public networks that offer mobile network services to the general public, 5G non-public networks provide 5G network services to a clearly defined user organization or groups of organizations, and they are deployed on the organization's defined premises, such as a campus or a factory. The main goal of this paper is to derive security threats and potential security requirements in the case that 5G non-public networks are built for discrete and process industries according to the four deployment models of 5G-ACIA (5G Alliance for Connected Industries and Automation). In order to clarify the scope of this paper, we express the security toolbox to be applied to 5G non-public networks in the form of the defense in depth concept. Security issues related to general 5G mobile communication services are not within the scope of this paper. We then derive the security issues to consider when applying the 5G-ACIA deployment models to the industrial domain. The security issues are divided into three categories, and they are described in the order of overview, security threats, and potential security requirements.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.3
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• pp.23-29
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• 2002

A wall-frame type structural system has been widely used to make full use of a limited land in large cities to satisfy the several functional requirement in one building. However, this type of hybrid structure brought some problems due to the vertical discontinuity of a structural system. The response of a wall-frame type structural system having a deep transfer girder was observed. An arch system was introduced to replace the deep transfer girder. The adequacy of an arch system was observed for the various boundary conditions of a system. The proposed system was compared to a general transfer girder system by applying both gravity load and lateral load. It was observed that an arch system fairly distributes the stress without concentrating stress at a certain location of a system differently from the current transfer girder system. The moment decrement effect of a column can also be obtained by eliminating the large mass of a transfer girder. Also it was investigated that an arch system is more economical and effective than the current transfer girder system.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.3
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• pp.69-77
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• 2003

This paper presents test results on eight reduced beam section(RBS) steel moment connections. The testing program addressed bolted versus welded web connection and panel zone(PZ) strength as key variables, Specimens with medium PZ strength were designed to promote energy dissipation from both PZ and RBS regions such that the requirement for expensive doublet plates could be reduced. Both strong and medium PZ specimens with a welded web connection were able to provide satisfactory connection rotation capacity for special moment-resisting frames. On the other hand, specimens with a bolted web connection performed poorly due to premature brittle fracture of the beam flange of the weld access hole. If fracture within the beam flange groove weld was avoided using quality welding, the fracture tended to move into the beam flange base metal of the weld access hole. Plausible explanation of a higher incidence of base metal fracture in bolted web specimens was presented. The measured strain data confirmed that the classical beam theory dose not provide reliable shear transfer prediction in the connection. The practice of providing web bolts uniformly along the beam depth was brought into question. Criteria for a balanced PZ strength improves the plastic rotation capacity while reduces the amount of beam distortion ore also proposed.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1099-1104
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• 2007

The visual implementation of 3-dimensional national environment is focused by the requirement and importance in the fields such as, national development plan, telecommunication facility deployment plan, railway construction, construction engineering, spatial city development, safety and disaster prevention engineering. The currently used DEM system using contour lines, which embodies national geographic information based on the 2-D digital maps and facility information has limitation in implementation in reproducing the 3-D spatial city. Moreover, this method often neglects the altitude of the rail way infrastructure which has narrow width and long length. There it is needed to apply laser measurement technique in the spatial target object to obtain accuracy. Currently, the LiDAR data which combines the laser measurement skill and GPS has been introduced to obtain high resolution accuracy in the altitude measurement. In this paper, we first investigate the LiDAR based researches in advanced foreign countries, then we propose data a generation scheme and an algorithm for the optimal manage and synthesis of railway facility system in our 3-D spatial terrain information. For this object, LiDAR based height data transformed to DEM, and the realtime unification of the vector via digital image mapping and raster via exactness evaluation is transformed to make it possible to trace the model of generated 3-dimensional railway model with long distance for 3D tract model generation.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.868-875
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• 2015

In order to replace existing slit type steel plate on the wooden structure joint, the FRP-reinforced laminated plates were produced. Four types of FRP-reinforced laminated plates were produced according to the type of reinforcement and adhesive, and before applying to the joint, the adhesion performance test according to KSF 3021 and KSF 2160 and the Compact Tension (CT) type fracture toughness test specified in ASTM D5045-99 were carried out. As a result of adhesion performance test, all GFRP textile, GFRP sheet, and GFRP Textile-Sheet type FRP-reinforced laminated plates satisfied the requirement of soaking delamination percentage with smaller than 5% based on KS standard. However, aramid type specimen satisfied the standard as the soaking delamination percentage of 4.8% but it did not satisfied the standard as the water proof soaking delamination percentage of 70%. As a result of fracture toughness test, the volume ratio of reinforcement to timber became 23% so that the strength of FRP-reinforced laminated plates increased by two to four times in comparison to the control specimen. It was confirmed that the GFRP Textile-Sheet type specimen was most resistant to the fracture most since the ratio of stress intensity factor compared with that of the control increased to 61% owing to the parallel arrangement of glass fiber to the load. As a result of tensile shear strength test using FRP-reinforced laminated plates and nonmetal dowels, it is about 12% lower than metal connectors.

• Fire Science and Engineering
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• v.26 no.2
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• pp.1-10
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• 2012

While a performance based sprinkler design method has been widely used in UK and USA according to fire hazards of occupancies, Korean fire safety industry could not yet accept it due to nonstandardization on risk level of various occupancy. Even only two or three spray pattern sprinkler was produced in Korea fire safety industry, therefore, various spray pattern sprinklers have not yet introduced to major occupancies. Spray pattern sprinklers with one of two K value have been used in all occupancies in Korea Market. UK and USA's Fire industry should produced the spray sprinklers with various K-factors and protection area due to performance based sprinkler design requirement. Therefore the fire load density for main occupancies has been investigated in order to compare with installation standard in advanced countries. Eventually a lot of variations in orifice and K factors of standard heads were set up including special heads needed for high hazard areas such as large drop type, enlarged orifice type and early suppression fast response.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.711-718
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• 2010

The requirement of the maximum yield strength of shear reinforcement in the KCI-07 code is quite different to those in the ACI-08 code, EC2-02, CSA-04, and JSCE-04 codes. Eighteen RC beams having high strength shear reinforcement were tested. Test results indicated that even if the yield strength of shear reinforcement in beams was much greater than the maximum yield strength required by the KCI-07 design code, the shear reinforcement of these beams reached their yield strains. Furthermore, the shear strengths of tested beams increased almost linearly with the increase of the amount of shear reinforcement. In addition, larger numbers of diagonal cracks developed in the web of the beam having greater yield strength than the beams having lower yield strength of shear reinforcement. The maximum crack width of the beam having high strength shear reinforcement was approximately the same to the crack with of the beam having normal strength shear reinforcement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.917-923
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the KHST test train. The object of this study was 3 kind of cars; trailer car(TT2), motorized car(TM1) and power car(TP1) and the predicted noise was calculated for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from each manufactures. Some of noise sources which were not available in project team, were chosen by experiences of ODS. Internal noise level of each car were predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated of each section of car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is floor in terms or structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TM1 are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TM1 are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.