• Journal of the Economic Geographical Society of Korea
• /
• v.19 no.2
• /
• pp.378-398
• /
• 2016

This paper aims to clarify the process of institutionalization of customary land ownership along with the expansion of coffee plantation in Dak Lak Province, Vietnam. Vietnam is the second-largest coffee exporter in the world. Most of the coffee areas are concentrated in Dak Lak-a province of commercial agricultural production. The expansion of coffee plantation in Dak Lak have brought a severe competition of land resources, and resulted in the transition of land ownership scheme from customary commons by ethnic minorities to those of exculsive private assets which is secured by the state. Institutionalization of customary land ownership in Dak Lak, however, was differently happened according to the geography from the center of state power as well as the value of land resources. In this paper, the authors argue that institutionalization of customary land ownership in Dak Lak was a result of compromising between statemaking process in the frontiers and "everyday resistance" of ethnic minorities, comparing 3 geographically different ethnic minorities' communities.

• Journal of The Korean Association For Science Education
• /
• v.18 no.4
• /
• pp.643-650
• /
• 1998

In order to assess students' higher mental abilities, such as scientific inquiry thinking skills, the essay type items would be more adequate than the multiple choice itmes. However, due to the present condition in which a huge number of students take the examination at the same time, it is inevitable to use the multiple choice type. For this reason, it is necessary to develop a new type of multiple choice items which can reduce the disadvantages of the traditional multiple choice type and can achieve a similar level of validity as subjective type assessment. The three-tier multiple choice test items which can be used for a large sample of students and especially for scientific inquiry thinking abilities, are proposed and examined. The three-tier multiple choice test items asked firstly conclusion or the results of calculation or experimental apparatus, secondly the processes of calculation or of developing conclusion, thirdly asking relevant scientific concepts. For the item analysis, 1 point was given to the correct answer, while 0 point was given to the wrong one. The data were processed through the computer program developed in Turbo C 2.0 language with an IBM compatable personal computer. The average score in the sub-items asking for scientific concepts was lower than that in the sub-items asking for results or processes. The score of guessing by chance in the three-tier multiple choice items was only 0.13%, so that the probability of making correct answers by just guessing would be extremely low. The three-tier multiple choice items, even if they are objective items, are thought to assess thinking skills of the scientific inquiry meaningfully excluding the possibility of guessing by chance.

• Korean Journal of Soil Science and Fertilizer
• /
• v.35 no.6
• /
• pp.327-334
• /
• 2002

Method of besoil analysis were difficult to be applied universally since the use and the source material of bedsoils are diverse from country to country. Korean Standard Methods for Bedsoil Analysis was developed to measure the particle and bulk density. Fifty-three samples for horticultural bedsoil and nine samples for paddy rice bedsoil in the current market were collected. Particle density was measured by electrical pyconometer with He gas, and bulk density by the sandbox method, free fall method, plunger compaction method, free fall and plunger method, and sample weight compaction method. While the use of glass pycnometer which measures particle density to fill blank space with water was inappropriate due to floating organic and calcined inorganic materials in the water, the electrical pycnometer with gas type was suitable considering speed and accuracy. For bulk density, the sandbox method recommended as European Standard Method was more reasonable in principle than other methods. However, this method requires expensive apparatus and intricate process. Plunger compaction method was proposed as standard method, since it had higher consistence with the sandbox method than other methods, as well as an advantage of easy and prompt measurement. Particle density of bedsoil ranged $1.48{\sim}2.67Mg\;m^{-3}$(mean $1.93Mg\;m^{-3}$) for horticultural bedsoil and $2.33{\sim}2.67Mg\;m^{-3}$ (mean $2.43Mg\;m^{-3}$) for paddy rice bedsoil by the electrical pycnometer with He gas. Bulk density of bedsoil ranged $0.11{\sim}0.40Mg\;m^{-3}$ (mean $0.22Mg\;m^{-3}$) for horticultural bedsoil and $0.84{\sim}1.26Mg\;m^{-3}$(mean $1.01Mg\;m^{-3}$) for paddy rice bedsoil by plunger compaction method.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.44 no.3
• /
• pp.10-21
• /
• 2021

Recently, the demand for atypical structures with functions and sculptural beauty is increasing in the construction industry. Existing mold-based structure production methods have many advantages, but building complex atypical structures represents limitations due to the cost and technical characteristics. Production methods using molding are suitable for mass production systems, but production cost, construction period, construction cost, and environmental pollution can occur in small quantity batch production. The recent trend in the construction industry calls for new construction methods of customized small quantity batch production methods that can produce various types of sophisticated structures. In addition to the economic effects of developing related technologies of 3D Concrete Printers (3DCP), it can enhance national image through the image of future technology, the international status of the construction civil engineering industry, self-reliance, and technology export. Until now, 3DCP technology has been carried out in producing and utilizing residential houses, structures, etc., on land or manufacturing on land and installing them underwater. The final purpose of this research project is to produce marine structures by directly printing various marine structures underwater with 3DCP equipment. Compared to current underwater structure construction techniques, constructing structures directly underwater using 3DCP equipment has the following advantages: 1) cost reduction effects: 2) reduction of construct time, 3) ease of manufacturing amorphous underwater structures, 4) disaster prevention effects. The core element technology of the 3DCP equipment is to extrude the transferred composite materials at a constant quantitative speed and control the printing flow of the materials smoothly while printing the output. In this study, the extruding module of the 3DCP equipment operates underwater while developing an extruding module that can control the printing flow of the material while extruding it at a constant quantitative speed and minimizing the external force that can occur during underwater printing. The research on the development of 3DCP equipment for printing concrete structures underwater and the preliminary experiment of printing concrete structures using high viscosity low-flow concrete composite materials is explained.

• Journal of the Korean Society for information Management
• /
• v.36 no.3
• /
• pp.81-107
• /
• 2019

The purpose of this study is to assert the justification for actively accepting media education in Library and Information Science and to suggest the media type according to the concept and classification criteria of the media from the perspective of Library and Information Science. In order to present the media type according to the concept of the media, the dictionary concept of the media was reviewed, the language and media for high school students in Korean language, the educational materials for elementary and secondary school students written by Media Education Committee of Korean Society for Journalism & Communication Studies, the educational textbooks for elementary and secondary school students in Library and Information Science, and media classification presented in the RDA of the cataloging rules were analyzed. In addition, the implications were derived based on the analysis results of the concepts and media type. The concept of media was set based on the analysis results and implications, and the media types were presented according to the concepts and classification criteria. In this study, the media was set up in the same meaning as the medium, and it was defined that the media function as a means of communication and that information contained in it can be obtained through the human sensory apparatus through physical objects that contain, transmit or reproduce information. The media was set up as three logical components of the media in this study: information in the media, materials, and representation devices.

• Journal of the Korean Academy of Esthetic Dentistry
• /
• v.27 no.2
• /
• pp.82-96
• /
• 2018

3D printing is a process of producing 3d object from a digital file in STL format by joining, bonding, sintering or polymerizing small volume elements by layer. The various type of 3d printing is classified according to the additive manufacturing strategies. Among the types of 3D printer, SLA(StereoLithography Apparatus) and DLP(Digital Light Processing) 3D printer which use polymerization by light source are widely used in dental office. In the previous study, a full-arch scale 3d printed model is less precise than a conventional stone model. However, in scale of quadrant arch, a 3d printed model is significantly precise than a five-axis milled model. Using $3^{rd}$ Party dental CAD program, full denture, provisional crowns and diagnostic wax-up model are fabricated by 3d printer in dental office. In Orthodontics, based on virtual setup model, indirect bracket bonding tray can be generated by 3d printer. And thermoforming clear aligner can be fabricated on the 3d printed model. 3D printed individual drilling guide enable the clinician to place the dental implant on the proper position. The development of layer additive technology enhance the quality of 3d printing object and shorten the operating time of 3D printing. In the near future, traditional dental laboratory process such as casting, denture curing will be replaced by digital 3D printing.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.5
• /
• pp.117-127
• /
• 2008

The volumetric pressure plate extractor (VPPE) was modified for the measurement of shear wave velocity ($V_s$) at various levels of matric suction as well as soil water characteristic curve (SWCC). A non-destructive technique with a pair of bender element (BE) was employed in order to measure the $V_s$ and the corresponding maximum shear modulus ($G_{max}$) of unsaturated soil specimens. Three types of soil were collected from different road construction sites in Korea. For all test soils, the variations in $G_{max}$ with the various levels of water content and matric suction were investigated using the developed apparatus. Compared with the preceding results from the suction-controlled torsional shear (TS) testing system and in-situ seismic tests, the feasibility fur evaluating modulus characteristics of unsaturated compacted soils with the developed VPPE-BE system was assessed. It was confirmed that the newly developed system would be potentially helpful in modeling seasonal variation of modulus.

• Journal of the Korean Institute of Gas
• /
• v.27 no.2
• /
• pp.7-15
• /
• 2023

The electric submersible pump (ESP) has been operating in production wells around the world because of its high applicability and operational efficiency among artificial lift techniques. When operating an ESP in a reservoir, variables such as temperature, pressure, gas/oil ratio, and flow rate are factors that affect ESP performance. In particular, free gas in the production fluid is a major factor that reduces the life and operational efficiency of ESP. This study presents the flow loop system which can implement the performance and damage tests of ESP considering field operating conditions to quantitatively analyze the variables that affect ESP performance. The developed apparatus in an integrated system that can diagnose the failure and causes of ESP, and detect leak of tubing by linking ESP and tubing as one system. In this study, the flow conditions for stable operation of ESP were identified through single phase and two phase flow experiments related to evaluation for the performance of ESP. The results provide the basic data to develop the failure prediction and diagnosis program of ESP, and are expected to be used for real-time monitoring for optimal operating conditions and failure diagnosis for ESP operation.

• Korean Journal of Hazardous Materials
• /
• v.2 no.1
• /
• pp.18-26
• /
• 2014

We analyzed the demand of competent authorities requiring adequate technical information for initial investigation of chemical accidents. Reflecting technical reports on chemical accident response by environmental agencies in the U.S. and Canada, we presented information on environmental diffusion and toxic effects available for the first chemical accident response. Hydrogen fluoride may have the risk potential to corrode metals and cause serious burns and eye damages. In case of inhalation or intake, it could have severe health effects. The substance itself is inflammable, but once heated, it decomposes producing corrosive and toxic fume. In case of contact with water, it can produce toxic, corrosive, flammable or explosive gases and its solution, a strong acid, may react fiercely with a base. In case of hydrogen fluoride leak, the preventive measures are to decrease steam generation in exposed sites, prevent the transfer of vapor cloud and promptly respond using inflammable substances including calcium carbonate, sodium bicarbonate, ground limestone, dried soil, dry sand, vermiculite, fly ash and powder cement. The method for fire fighting is to suppress fire with manless hose stanchions or monitor nozzles by wearing the whole body protective clothing equipped with over-pressure self-contained breathing apparatus from distance. In case of transport accident accompanied with fire, evacuation distance is 1,600m radius. In cae of fire, fire suppression needs to be performed using dry chemicals, CO₂, water spray, water fog, and alcohol-resistance foam, etc. The major symptoms by exposure route are dyspnoea, bronchitis, chemical pneumonia and pulmonary edema for respiration, skin laceration, dermatitis, burn, frostbite and erythema for eyes, and nausea, diarrhea, stomachache, and tissue destruction for digestive organs. In atmosphere, its persistency is low, and its bioaccumulation in aquatic organism is also low.

• Journal of the Korean Institute of Gas
• /
• v.27 no.4
• /
• pp.62-69
• /
• 2023

The use of low-grade coal is continuously increasing with the development of combustion technology and cost reduction for coal used in thermal power plants . During combustion, the latent heat of evaporation due to moisture is large, and there is a risk of spontaneous combustion and dust explosion during the process of storing and pulverizing coal. This study compared and evaluated the minimum explosive concentration and explosive strength of four types of coal dust-fine, coal dust-coarse, wood pallet+organic dust, and wood chip with coal powder collected from domestic power plant D. The minimum explosive concentration of coal dust was measured according to JIS Z 8818:2002, and the explosion strength was tested according to ASTM E1226 using a Siwek 20 L Chamber Apparatus. As a result of the minimum explosive concentration test, it was found that coal dust-fine has a risk of dust explosion, and since an explosion occurs at a dust concentration of 130 g/m³ of wood chips, it was found that there is a risk of explosion at the lowest dust concentration. According to the dust explosion class standard, Kst is less than 200 bar m/s, and all samples fall under the explosion class St 1, and the dust has a low risk of explosion.