• Journal of Powder Materials
• /
• v.1 no.2
• /
• pp.181-189
• /
• 1994

The compacts of pure and phosphorus-coated iron powder with 0~0.8%C were sintered at $1100^{\circ}C$ for 40 min. in cracked ammonia gas atmosphere. The tensile and impact strengths were measured and the relationship of the results with carbon content, phosphorus, quenching and tempering was investigated. The results obtained can be summarized as follows : (1) The tensile strength of sintered compacts increased slowly with carbon content. Increase in tensile strength by heat treatment was evident especially in the low carbon specimen. The specimen with phosphorus showed higher strength compared to pure iron compacts value. (2) No inflection point of elasticplastic deformation on stress-strain curve was observed in sintered steel. The elastic modulus of sintered steel had the same tendency as tensile strength. But the elongation showed the opposite tendency. (3) The impact absorption energy of sintered steel without addition of phosphorus decreased successively with carbon content and by quenching and tempering. On the contrary, addition of phosphorus resulted in an increase of the impact absorption energy. Quenching and tempering did not affect the impact energy especially in high carbon content. (4) The main fracture source was pore in specimen and the propagation of crack occured mostly along the grain boundaries. But the intragranular fracture was also observed in high carbon, quenched and tempered specimen, and especially in the specimen with phosphorus.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.12
• /
• pp.3847-3855
• /
• 1996

In order to study the relationship between static and cynamic behaviors of silion caride, both quasi-static indentaiton and impact experiments of spherical particle have been conducted. The difference inmaterial behavior when using the two mehtods suggests a loading rate difference in the damate pattrern and fracture strength of silicon carbide. This investigation showed some difference in damage pattern according to particla property, especially inthe case of particle impact. There was no differences in deformation behaviors according to the loading rate when the crater profiles were compared with each other at the same contact radius. From the result of residual strength evaluation, it was found that the strength degradation began at the initiation of ring crack and its behavior was colsely related to morphologies of the damage developed which was also dependent upon the extent of deformation atthe loaidng point. In the case of static indentation, there didnot exist the particle property effects onthe strength degradation behavior.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.8
• /
• pp.1066-1073
• /
• 2013

This paper illustrates newly an outage cost impact index function(OCIIF). The assessment of the OCIIF is described using the Web Based Online Real-time Outage Cost Assessment and Information System(WOROCAIS) for power system outage cost assessment in Korea. The proposed OCIIF is not absolute but relative outage cost impact index function in view point of outage time using web based survey method for outage cost assessment. While conventional methodology does not consider short time outage cost assessment, the proposed OCIIF reflects short time outage. SCOF(Sector Customer Outage Function) in stead of the traditional SCDF(Sector Customer Damage Function) is defined and proposed newly in this paper. Based the SCOF, AVLL(Average Value of Loss Load) is newly proposed. The OCIIF is demonstrated by WOROCAIS in case study around 2,000 sample data surveyed by KEPCO in South Korea in recent.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.11 s.104
• /
• pp.1311-1317
• /
• 2005

In environmental Impact assessment, noise impact assessment usually consists of three stages-surveying the existing noise levels by measurements, predicting noise levels induced by construction works and predicting noise levels after the completion of a project. The distance-attenuation relation of a point source, which has been used to predict the noise level due to its simplicity does not consider complex acoustic phenomena like multi-reflection, -diffraction and -absorption due to complex topographic configuration of buildings and terrains. For the consideration of such physical complexities. a noise mapping tool is adopted to produce a series of noise maps, which are those for the present, tot the works of construction and for the future. For accurate noise mapping, acoustical and topographic Information is used. Standard sound power levels and directivities of various construction equipments are need and scheduling of construction processes and locations of the equipments should be provided. In the case of exceeding legal limit, mitigation measures are applied to satisfy the legal limits and subsequent noise map is obtained and checked.

• International conference on construction engineering and project management
• /
• 2015.10a
• /
• pp.361-366
• /
• 2015

The objective of this paper was to establish the attributes that determines neighbourhood satisfaction in South Africa lowincome housing subsidy scheme ultilising the Delphi approach. This is because the perception and housing satisfaction of lowincome housing beneficiaries toward their housing condition can be studied by examining their satisfaction toward s the neighbourhood factors. The Delphi method was used where the views of housing experts were solicited on 26 potential attributes as identified from li terature. Consensus was achieved after three iterative rounds. The expert"s scored each attributes on a 10-point ordinal scale of impact significance, where 1-2=No impact and 9-10= very high impact. The scales adapted for consensus were: strong consensus, median 9-10, inter quartile deviation (IQD) ≤1; good consensus, median 7 ≤ 6.99and IQD≥2.1≤3. The key findings indicate that there was a good to strong consensus of 19 attributes which were key attributes that the experts perceived as determinants of neighbourhood satisfaction; while 6 other attributes had weak consensus, as they were considered to have a le sser impact in determining residents" neighbourhood satisfaction. However, attributes with weak consensus were the attributes that are highly regarded as core neighbourhood factors in other housing settings. The study contributes to the body of knowledge on th e subject where no consensus has been reached pertaining to indicators for measuring neighbourhood satisfaction in subsidised low-income housing in South Africa.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.7
• /
• pp.1131-1138
• /
• 2001

This paper concerns the crashworthiness of the widely used vehicle structure, the spot welded hat and double hat shaped section members, which are excellent on the point of the energy absorbing capacity and low production cost. The target of this paper is to analyze the energy absorption capacity of the structure against the front-end collision, and to obtain useful information for designing stage. Changing the spot weld pitches on the flanges, the hat and double hat shaped section members were tested on the axial collapse loads in impact velocities of 4.72m/sec, 6.54m/sec, 7.19m/sec and 7.27m/sec. To efficiently review the collapse characteristics of these sections, the simulation have been carried out using explicit FEM package, LS-DYNA3D. The solutions are compared with results from the impact collapse experiments.

• The Journal of Industrial Distribution & Business
• /
• v.15 no.1
• /
• pp.1-8
• /
• 2024

Purpose: The purpose is to investigate the types of communication between aviation industry workers and passengers according to environmental changes following the COVID-19 pandemic. This study analyzes the impact of verbal and non-verbal communication styles of airport staff, especially those working at airline check-in counters, on passenger satisfaction. Research Design: The research design focuses on the impact of verbal communication styles and non-verbal communication factors of airline check-in counter staff, who represent the initial point of contact with passengers among airport staff, on passenger satisfaction. The survey period for sample collection was from July 1 to July 30, 2023, and the study was conducted targeting passengers boarding aircraft through Incheon Airport and Gimpo Airport. Result: First, it is important for airport staff to recognize all passengers, especially corporate customers, as corporate customers rather than simply as individuals boarding an airplane. Second, as the importance of non-verbal expressions increases due to the impact of COVID-19, physical and verbal responses are necessary. Third, it is important to check which language the passenger understands. Conclusions: Since communication through nonverbal expressions has become more important since COVID-19, airport employees need to recognize the importance of nonverbal communication. This awareness can serve as a foundation for building trust between airport staff and passengers.

• Journal of the Korea Concrete Institute
• /
• v.28 no.4
• /
• pp.455-462
• /
• 2016

This experimental study aims to evaluate the impact performance of UHPC exterior panels through high velocity impact tests. The impact performance of UHPC was compared with that of granite in terms of panel thickness, and strain histories were recoded on the rear face of panel specimens. The UHPC turned out to be a good exterior facade material, because the appearance of UHPC is natural enough and impact performance was superior to granite. After colliding, compression pulse reached to the rear face but that pulse was reflected in tension pulse with respect to the free point outside the rear face of the panel. This tension pulse caused the scabbing from the rear side, as the strain histories on the rear face showed three different regions as compression region, steady region and tension region. The shear plug deformation by shear force also was one of the primary reasons for the scabbing based on the observation. Therefore, the scabbing seemed to be affected by both tension and shear forces.

• Journal of the Korea Convergence Society
• /
• v.11 no.4
• /
• pp.173-177
• /
• 2020

In this study, the side doors of mid-size sedan vehicles of models A and B which are currently prone to rollover accidents are compared with each other by the structural analyses. As a result of the structural analysis, both models showed the maximum deformation at the point of overturning or impact load, and the model A of the two models was able to withstand greater impact load compared to the model B. In addition, the maximum stress happened at the door edge, and model B was 2.5 times more stressed than model A. In the accident of a crash, model A, which has the smaller maximum stress, is able to withstand greater impact loads than model B. Since model B has a larger deformation than model A, it is considered to be more dangerous than model A in the side impact accident. By applying the impact analysis of automotive side door by the class of vehicle, the study result at this paper is considered to be favorable as the convergent research material which can apply the aesthetic design.

• Composites Research
• /
• v.14 no.2
• /
• pp.22-32
• /
• 2001

Damage induced by low-velocity impact on the curved composite laminates was experimentally evaluated for CFRP cylindrical shells with the radius of curvatures of 50, 150, 300, and 500 mm. The result was then compared with that of flat laminates and with the results by nonlinear finite-element analysis. The radius of curvatures and the effective shell stiffness appeared to considerably affect the dynamic impact response of curved shells. Under the same impact energy level, the maximum contact force increased with the decreasing radius of curvatures, with reaching 1.5 times that for plates at the radius of curvature of 50 mm. Since the maximum contact farce is directly related to the impact damage, curved laminates can be more susceptible to delamination and less resistant to the low-velocity impact damage. Delamination was distributed rather evenly at each interface along the thickness direction of curved laminates on the contrary to the case of flat laminates, where delamination is typically concentrated at the interfaces away from the impact point. This implies that the effect of curvatures has to be considered for the design of a curved composite laminate.