• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.329-335
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• 2001

Recently, in many laboratories and institutes it is being studied on the high flowing concrete widely, which has high fluidity, non-segregation ability and fillingability, and sometimes being applied to the construction field actually. And the fluidity properties of high flowing concrete are influenced according to the several factors ; binder content, water/binder ratio and water content etc. This is an experimental study to compare and analyze the effect of water/binder ratio and water content on the properties of high flowing concrete. For this purpose, the mix proportion of high flowing concrete according to water/binder ratio(W/B : 0.30, 0.35, 0.40, 0.45) and water content (W : 155, 165, 175, 185 kg/㎥) was selected. And then slump-flow, V-lot, L-passing test in fresh concrete, and compressive strength, freezing and thawing test in hardened concrete were peformed. According to test results, it was found that the viscosity of all those high flowing concrete with the water content 175 kg/㎥ was satisfied with 50 cm pass time of slump flow prescribed by Japanese Architectural Standard Specification (JASS 5) - from 3 to 8 seconds. And non-segregation ability of concrete with W/B 0.35 was better than the other mix proportions. Especially, the compressive strength after curing 24 hours(1 day) of all high flowing concrete was higher than that prescribed by JASS 5(50 kgf/㎠).

• Journal of Environmental Health Sciences
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• v.36 no.5
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• pp.391-401
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• 2010

A reduction in risk of occupational exposure to chemical hazards within the workplace has been the focus of attention both through industry initiatives and legislation. The aims of this study were to develop an exposure matrix by industry and process, and to apply this matrix to control the risk of occupational exposure to Dichloromethane (DCM). The exposure matrix is a tool to convert information on industry and process into information on occupational risk. The exposure matrix comprised industries and processes involving DCM, based on an exposure database provided by KOSHA (the Korean Occupational Safety and Health Agency), which was gathered from a workplace hazards evaluation program in Korea. The risk assessment of the exposure matrix was performed using Hallmark risk assessment tool. The results of the risk assessment were indicated by a Danger Value (DV) calculated from the combination of hazard rating (HR), duration of use rating (DUR), and risk probability rating (RPR) of exposure to the chemical, and were divided into four control bands which were related to control measures. The applicability of the risk assessment of the exposure matrix was evaluated by a field study, and survey of the employees of the exposure matrix groups. Among 45 industries examined, this study found that greater attention should be paid to two industries: the manufacture of other optical instruments and photographic equipment, and the manufacture of printing ink, and to one process among 47 examined, the packing process in the manufacture of printing ink, because these were regarded as carrying the highest risk. This tool of a risk assessment for the exposure matrix can be applied as a general exposure information system for hazard control, risk quantification, setting the occupational exposure limit, and hazard surveillance. The exposure matrix includes workforce data, and it provides information on the numbers of exposed workers in Korea by agent, occupation, and level of exposure and risk.

• Journal of the Korean GEO-environmental Society
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• v.21 no.7
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• pp.17-26
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• 2020

The soft ground in the southwest coastal area composed of marine clay is greatly influenced by sediment composition, particle size distribution, particle shape, adsorption ions and pore water characteristics, tide and temperature. In addition, the geotechnical properties are very complex due to stress history, change in pore water, dissolution process and gas formation. In this study, the physical and mechanical properties of the soft ground were evaluated through field tests and laboratory tests to investigate the strength increase characteristics according to consolidation on the soft ground in the southwest coast. In addition, in order to understand the consolidation behavior of soft ground such as subsidence, pore water pressure, horizontal displacement of soil by embankment load, measuring instruments such as pore water pressuremeter, settlement gauge, inclinometer and differential settlement gauge was installed, and a piezocon penetration test was carried out step by step to confirm the increase in shear strength of the ground. Through this, it was confirmed that the shear strength of the ground is increased according to the stages of filling. In addition, by evaluating the properties of consolidation behavior, strength increase and consolidation prediction by empirical methods and theories were compared to analyze the characteristics of strength increase rate and consolidation behavior in consideration of regional characteristics.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.65-72
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• 2016

ORC system was designed and constructed for utilizing the heat of the exhaust gas and coolant released from the gas engine which was modified to use natural gas as a fuel. In this paper the components of the ORC system were designed and manufactured based on measured data of the gas engine. The components are composed of two plate heat exchanger, the 5kW-class expander and multi stage centrifugal pump. The thermodynamic performance of the ORC system was analyzed by using the electric heater. Also, the developed ORC system was implemented to modified natural gas engine. Two gas engines were used to supply heat to the ORC system. As a result of test bench, when the heat source temperature is $110^{\circ}C$ expander shaft power, the pressure ratio and cycle efficiency is 5.22kW, 7.41, 9.09%. As a result of field test, when the heat source temperature is $86^{\circ}C$ expander shaft power, the pressure ratio and cycle efficiency is 2kW, 3.75, 6.45%.

• 대한공업교육학회지
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• v.44 no.2
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• pp.1-27
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• 2019

In recent years, space planning ability using 3D sketch software is required in the working field of interior design. However, vocational high school do not respond appropriately to changes in the industry, because the class of vocational high school consists of hands-on practical classes and 2D CAD based classes. There is a shortage of 3D sketch software-based instruction programs that can improve students' spatial planning skills. Therefore, this study is to develop instruction program using 3D sketch software for 'Planning for Residential Space' unit of NCS-based on interior design subject and to find out the effect on students' academic achievement by applying to vocational high school class. The 3d sketch software based instructional program developed in this study was developed through four stages of preparation, development, implementation and evaluation according to the PDIE model process. The experimental design model used nonequivalent group posttest-only design in this study. Experiments were conducted on vocational high school students in construction and 9 hours of interior design subjects were applied. After the experiments, students were tested for academic achievement in the cognitive, affective, and psychomotor areas. As a result, the instruction program using the 3d sketch program developed in this study was found to be more effective in improving students' academic achievement than existing manual instruction program in both cognitive, affective, and psychomotor areas.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.433-438
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• 2006

When we consider to develop a new harbor, the most important factor, we think, is the lowest water depth of waterway and approaching channel for safe navigation of vesse. The existing harbors have been being dredged to meet the international trend of jumbo sized vessels by adopting the new design criteria. As the dredged materials over the expected at the design level were common and there are still lack of land based reclamation area, we have no choice to discharge the dredged materials in open sea area. In this study, we analysed the behavior of discharged materials at the dumping area of offshore open sea, which were collected from the dredging work at the waterway in Busan New Port. We measured the tidal currents and analyzed the waters of dumping site after the dumping work. these were used to evaluate the numerical models. Suspended Solids(SS) were introduced to the diffusion model. Because of the characteristics of the dumping site, the speed of initial diffusion and settle down of the discharged materials was so fast. Therefore, we believe that the dumped materials do not cause a significant impact to the marine environment.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.3
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• pp.105-113
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• 2010

This study is for the preservation plan of the tradition space which is performed by the damage status analysis through performing the value assessment. Especially, it is an experimental study for finding the process and methods by analyzing the major element for the value assessment of the selected object's damage status through the expert group who are systematized in their interest to conserve the traditional structure in traditional space. For that purpose, this study should be performed by the fundamental understanding of the physical property of the Supyo-bridge and the condition of the selected site's environment. Meanwhile, this study has been done that 'map of the damage status distribution' for making records of damage status of the Supyo-bridge on the property utilized field measurement adapted by photogrammetry and assessment guidelines, which are for investigation on damage status of objects that are standardized 'Raccomandazioni Normal' which could be said construction culture assets management guidelines of Italian government. As the result of investigation, damage status of each part in the Supyo-bridge was mostly composed of damage by sediment and corrosion and in case of 9 damage types including corrosion, in consideration of physical and chemical properties and distribution status of those elements, it is made an judgement that is not working as a threatened factor regarding security of the Supyo-bridge. On the contrary, for the improvement landscape, in case of 'Thermoclastism' phenomenon observed in 'upper floor', 'Myungae stone' and 'bridge pier' is that when taking it into consideration that is widely distributed concentrated on the bridge pier, surface reinforcement job along with elimination of damage part will be judged to be requested for earliest treatment.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.3
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• pp.75-87
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• 2018

The purpose of this study is to investigate conservation and management methods of the Joseon Royal Tombs under the Eastern District Management Office. Through the literature survey, we understood the process of change of Joseon royal tombs, and through field surveys and interviews, we understood the status of the interior and the surrounding area. In this process, topography, land use and flow of human traffic, architecture and stone objects, water system, historical forests, and facilities were set as the main evaluation indicators. Urbanization has damaged the original terrains of Royal Tombs as national roads, buildings and facilities have constructed in the inner and outer area of Joseon Royal Tombs. Construction of underground passage, land purchase, relocation and demolition of the buildings are required for the conservation of the Royal Tombs area, and then it is necessary to recover the original terrain. In the case of land use and pathways, there are many disconnection of the original ritual circulation, they should be maintained to remind the sacred atmosphere of the royal tomb. And It is necessary to collect accurate information on the lost buildings and stoneworks through literature survey and excavation investigation, and that investigations should be lead to the exposure or restoration of the ruins. Historical forests require periodic and ongoing monitoring and management, and it is necessary to establish new entrance area and appropriate facilities following the long-Term conservation and management plan. These plans should be classified into short, medium and long-Term projects according to urgency and securing financial resources with a long perspective to implement continuous and systematic projects.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.117-124
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• 2005

Recently the first stage of construction for Busan new port emerged over the sea surface at the north container terminal site. With this, there are lot of discussions and debates on increasing the water depth at the approaching channel and mooring basin from the existing 15m to 18m by dredging work in order to be able to serve 12,000TEU containership, and at the same time, correction to the reclamation plan of hinterland at the part of Undong Bay of the new port site. Since the attack of typhoon 'Maemi' in 2003, it is expected that the design wave parameters for coastal and harbor structures in this area would be somewhat changed and so the extreme wave condition at each terminal and tranquility of berthing area does, and therefore, it is necessary to analyze the tranquility at each berth. Hence in this study, we constructed a wave model for these conditions and performed simulation together with the circulation model simulation, compared with the field data collected. The result showed the increase of the harbor response throughout the basin but not severe condition. However, a certain location needs to be prepared for the rough sea condition when a severe typhoon hit the site.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.167-178
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• 2002

Properties of discontinuity for Seoul Granite in northeastern part of Seoul City were analyzed by dividing structural domains into Surak and Bulam Mtn. areas. Important parameters measured among several engineering properties of a rock during tunnel excavation and road construction are as follows: 1) Orientation of joint, 2) joint spacing, 3) joint density, and 4) uniaxial compressive strength. Orientation, spacing, and density of joints can be directly measured during field investigation using scanline survey, circle-inventory method, and window survey. Uniaxial compressive strength of the rock was calculated by a simple correlation equation although it is originally necessary to prepare core samples in measuring it. Major orientations of joints measured from both areas are 3 sets of joints with different orientations. In other words, they are 2 sets of orthogonal joint and 1 set of sheet joint that is dipping at low angle, and have very similar orientations in both areas. Joint densities in both areas range from 0.039 and 0.066/cm, and average joint length are between 1.30 and 4.52m. Average joint spacing also has values from 10.3cm up to 59.6cm, and shows significant difference along specific orientation of scanlines measured. Values of uniaxial compressive strength calculated on the basis of Schmidt hammer rebound values range from 217 to 335 MPa, which indicates very strong rock type by classification of wall strength.