• Title/Summary/Keyword: 유동한계

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Analysis of Management Status and Optimum Production Scale of Quarrying Firms in Korea -Comparative Analysis of Aggregate and Building-Stone Quarrying Firms- (산지채석업체(山地採石業體)의 경영실태(經營實態) 및 적정규모설정(適正規模設定) -골재용(骨材用) 채석업체(採石業體)와 건축용(建築用) 채석업체(採石業體)의 비교(比較) 분석(分析)-)

  • Joung, Ha Hyeon;Cho, Eung Hyouk
    • Journal of Korean Society of Forest Science
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    • v.80 no.1
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    • pp.72-81
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    • 1991
  • This study was carried out to provide necessary information for improving quarrying industry management in Korea. The results of the study are summarized as follows : 1. In aggregate and building-stone quarrying firms the managers over 40 years of age are 97% and 89.1%, the ones above education level of high school are 90% and 85% and the ones not more than 10 years of quarrying experience are 70% and 52%, respectively. Accordingly it can be pointed out that most of the managers of two types of firms are relatively old, have high educational background, while quarrying experiences of building-stone firm managers are longer than that of aggregate firm managers. 2. Most of the management forms are social corporation(60%) for aggregate quarry firms and private management(76%) for building-stone firms. Average areas of permitted stone-pits of aggregate and building-stone quarries are about 2.86ha and 1.66ha respectively. That is, aggregate quarrying firms are carried on a larger scale than building-stone quarrying firms. 3. The yearly average product of aggregate quarrying firms has increased steadily from $88.961m^3$ in 1985 to $144.028m^3$ in 1988, while, in case of building-stone quarry firms, it has significantly increased from $4.155m^3$ to $19.462m^3$ from 1985 to 1987, but reduced to $13.400m^3$ in 1988. Unstable production activities of building-stone quarrying firms may require continuous government support. 4. Major cost items are equipment rental, depreciation, salaries, repair, maintenance for aggregate quarrying firms, and salaries, depreciation, fuel, tax for building-stone quarrying firms. The yearly average rate of return is about 9.7% for aggregate quarry firms and 2.6% for building-stone quarry firms. It can be pointed out that aggregate quarrying firms is better managed than building-stone quarrying firms. 5. The production elasticity of salary for aggregate quarrying firms is 0.495, that of employees is 0.559, and that of capital service is 0.513. The sum of the elasticities is 1.257>1. Fur building-stone quarrying firms, that of employees is 0.492, that of variable costs is 0.192, and that of capital service is 0.498. The sum of elasticities is 1.172>1, thus denotes the increasing returns to scale for both types quarrying firms. 6. The ratio of marginal value product to opportunity cost of empolyees is 2.54, that of variable costs is 3.62, and that of capital service is 1.45, in aggregate quarrying firms. That of employees is 2.47, that is variable costs was 2.34, and that of capital service is 19.67 in building-stone quarrying firms. Therefore the critical factors for more expansion of management scale in aggregate quarrying firms are variable cost and employees, and are capital service in building-stone quarry ing firms. 7. The break-even points of stone sales are about 0.587 billion won and 0.22 billion won in aggregate and building-stone quarrying firms respectively. The optimum sales Level for profit maximization are about 2.0 billion and 0.5 billion in aggregate and building-stone quarry firms respectively.

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Effect of Coagulants on the Behavior of Ultra Fine Dust in a Coal Firing Boiler (석탄 화력 보일러에서의 응집제 이용에 따른 초미세먼지 거동)

  • Ryu, Hwanwoo;Song, Byungho
    • Applied Chemistry for Engineering
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    • v.31 no.1
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    • pp.84-89
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    • 2020
  • Particulate matters of PM2.5, particularly focusing on 0.1~1 ㎛ decrease the efficiency of dust-collector due to the brownian-motion. This study is to verify the effect of coagulant on the particle size distributions of potassium and PM2.5. The activated coagulant was spayed to the coal fired fluidized bed combustion boiler by the weight ratio of 1,200 : 1 = coal : coagulant, and the size distributions of captured particles at both the cyclone (FP) and electrostatic precipitator (EP) were measured. As the result of XRP analysis, the potassium content of FP increased to 13.33% (averagely from 1.65% to 1.87%) and, in EP at 17.68% (averagely from 1.65% to 2.03%). And it was confirmed by the particle size distribution analyzer and SEM image analysis that the distribution rates of PM2.5 decreased at 89.53% on average in FP, and at 88.57% in EP. The total dust concentration (mg/㎥) confirmed by tele-monitering system (TMS) decreased during the primary test from 2.6 to 1.7~1.9 and also the secondary test from 2.9 to 1.7~1.9.

A Study on the Trends of Virtual Reality Application Technology for Agricultural Education (가상현실 응용기술의 동향 분석을 통한 국내 시설농업의 교육용 가상현실 활용방안 고찰)

  • Kim, Jun-Gyu;Lee, In-bok;Yoon, Kwang-Sik;Ha, Tae-hwan;Kim, Rack-woo;Yeo, Uk-hyeon;Lee, Sang-yeon
    • Journal of Bio-Environment Control
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    • v.27 no.2
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    • pp.147-157
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    • 2018
  • With the rapid development of the 4th industrial revolution, the large-sized facilities of agriculture have been developed with high-technologies. However, it is difficult to maintain the optimum environment in large-sized facilities. Although it is essential to control micro-climate properly in large-sized facilities, there are a lot of problems to utilize high-technologies and equipment because of insufficient education for farmers. Most farms have limitations to access to their farm because of prevention of epidemics, exposure of management know-how, and so on. Especially, it is difficult to understand internal environmental factors (airflow, temperature, humidity, etc.) for farmers because these factors are invisible. Recently, Virtual reality technology which allows users to experience various phenomena directly is attracting attention. Virtual reality is very useful technology to visualize airflow and temperature distribution and so on. However, there is no cases applied this technology to agricultural facilities. In this study, research trends of virtual reality in various fields were investigated. In particular, the limitation and possibility of virtual reality technology were analyzed for educating farmers. Finally, the development of virtual reality contents for smart-farm facility were suggested.

High Gain Observer-based Robust Tracking Control of LIM for High Performance Automatic Picking System (고성능 자동피킹 시스템을 위한 선형 유도 모터의 고이득 관측기 기반의 강인 추종 제어)

  • Choi, Jung-Hyun;Kim, Jung-Su;Kim, Sanghoon;Yoo, Dong Sang;Kim, Kyeong-Hwa
    • Journal of the Korean Institute of Intelligent Systems
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    • v.25 no.1
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    • pp.7-14
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    • 2015
  • To implement an automatic picking system (APS) in distribution center with high precision and high dynamics, this paper presents a high gain observer-based robust speed controller design for a linear induction motor (LIM) drive. The force disturbance as well as the mechanical parameter variations such as the mass and friction coefficient gives a direct influence on the speed control performance of APS. To guarantee a robust control performance, the system uncertainty caused by the force disturbance and mechanical parameter variations is estimated through a high gain disturbance observer and compensated by a feedforward manner. While a time-varying disturbance due to the mass variation can not be effectively compensated by using the conventional disturbance observer, the proposed scheme shows a robust performance in the presence of such uncertainty. A Simulink library has been developed for the LIM model from the state equation. Through comparative simulations based on Matlab - Simulink, it is proved that the proposed scheme has a robust control nature and is most suitable for APS.

Separation of Soybean Protein by Free-flow Electrophoresis (자유유동 전기이동법에 의한 대두단백질 분리)

  • 한재갑;류화원
    • KSBB Journal
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    • v.10 no.1
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    • pp.63-70
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    • 1995
  • The effect of operating conditions on separation of soybean proteins in a home-made free-flow electrophoresis apparatus was investigated. Measurement of the pH, conductivity, and UV-absorbance(280 nm) were carried out at each run and the purity of the sample was tested with SDS-PAGE analysis. The soybean extract pretreated with Tris and boric acid was mixed with the amino acids composed of glutamic acid, histidine, arginine, glycine(1 mM each) with glycyl-glycine(2mM) and KCl(1mM). When the cellulose acetate was used as a compartment between the electrode and the buffer solution in the cell, pH distribution in the separation cell varied from 3.0 at the anodic side to 8.0 at the cathodic side and had two inflection point. The applied voltage was from 300V to 1000V and the separation was better at a higher voltage but the voltage was limited by the capability of the cooling system due to Joule heat. The proteins focused near the middle of the channel. From the change of pH and conductivity it was found that the ions in the channel moved out to the electrodes through the membrane. In the case when the concentration of the buffer solution was increased 5 times, proteins were focused at 300V. We could not increase up to the ten times of the concentration since the temperature difference between inlet and outlet was more than $25^{\circ}C$ and denaturation of proteins was expected. When ion-exchange membranes were used U-type pH distribution was set up due to the ionic polarization near the membrane. The commercial ampholytes, instead of the mixed amino acids showed not much improvements in purity of the separated sample.

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Investigation of Turbulent Analysis Methods for CFD of Gas Dispersion Around a Building (건물주위의 가스 확산사고에 대한 CFD 난류 해석기법 검토)

  • Ko, Min Wook;Oh, Chang Bo;Han, Youn Shik;Do, Kyu Hyung
    • Fire Science and Engineering
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    • v.29 no.5
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    • pp.42-50
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    • 2015
  • Three simulation approaches for turbulence were applied for the computation of propane dispersion in a simplified real-scale urban area with one building:, Large Eddy Simulation (LES), Detached Eddy Simulation (DES), and Unsteady Reynolds Averaged Navier-Stokes (RANS). The computations were performed using FLUENT 14, and the grid system was made with ICEM-CFD. The propane distribution depended on the prediction performance of the three simulation approaches for the eddy structure around the building. LES and DES showed relatively similar results for the eddy structure and propane distribution, while the RANS prediction of the propane distribution was unrealistic. RANS was found to be inappropriate for computation of the gas dispersion process due to poor prediction performance for the unsteady turbulence. Considering the computational results and cost, DES is believed to be the optimal choice for computation of the gas dispersion in a real-scale space.

The stillness-motion interface designing of the Web, Based on the e-advertisement concept. (웹 인터페이스의 정.동디자인에 관한 연구 -e광고 컨셉트별 정.동디자인 분석-)

  • 전기순
    • Archives of design research
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    • v.15 no.4
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    • pp.317-326
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    • 2002
  • The Web has taken a strong post as one of the media for advertisement for long time. The Internet has an advantage of an easy access to each of customers; the fractioning of the potential customers; the transcending of the time and space; and the utilizing of the multimedia. As such, the Web as a communication tool has not only all characteristics of the existing media but also the factors such as the sound, motion, and interaction. Therefore the Web designing should be much more flexible and open than any other medias. Nevertheless, most of the Webs being created currently appear to be simply perfunctory and functional. This is because a methodological aspect has not been rooted firmly as the Web design industry has been developed too rapidly, driven by the explosive demand. Therefore, this study is designed to demonstrate the approaching method to the Web-interface designing as an alternative for such methodological aspect. In other words, it is the very stillness-motion interface designing of the Web, based on the e-advertisement concept. The Web as one of the media for advertisement gives the heaviest weight to the users emotional aspects than any other media do. Therefore, it is very important to get the differentiation and impact in the Web-interface designing through the users emotional aspects.

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A Rough Estimation of Environmental Capacity in the Yellow Sea using a Numerical Hydrodynamic Model (해수운동모델을 이용한 황해 환경용량의 개략 산정)

  • Kim Gwang Su;Kim Dong Myung;Park Chung Kil
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.2 no.1
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    • pp.63-73
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    • 1999
  • The results of residual currents simulation by a three-dimensional hydrodynamic model showed the water volume transport and the residence time to be about 4km³ per tidal cycle and about 6 years through the line of latitude, 34° 25' N in the Yellow Sea, and to be about 13km³ per tidal cycle and about 2.5 years through the southeastern boundary line of the Yellow Sea, respectively. On the bases of the entire seawater volume of the Yellow Sea and dissolved oxygen (DO) in summer, the environmental capacity of the Yellow Sea for reception of the maximum pollution load without reducing DO concentration below 5.0mg/ℓ in seawater may be estimated to be about 58×10/sup 6/tons of chemical oxygen demand (COD), which is equivalent to the load about 8 times as high as the annual organic pollution load from 14 major rivers. On the bases of DO transports by residual currents calculated on the line of 34° 25' N latitude and on the southeastern boundary line of the Yellow Sea being about 57×10³tons and about 203×10³tons of DO per day, respectively, the environmental capacities of the Yellow Sea for reception of the maximum pollution loads without reducing DO concentration in seawater nay be equivalent to COD loads about 3 times and 10 times, respectively, as high as the existing organic pollution loads from 14 major rivers.

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A Study on the Prevention Measures against Fire and Explosion Accidents during Splash Filling in Batch Process (회분식 공정에서 스플래쉬 필링(Splash Filling) 작업으로 인한 화재·폭발 사고 예방대책에 관한 연구)

  • Kim, Sang Ryung;Lee, Dae Jun;Kim, Jung Duk;Kim, Sang Gil;Yang, Won Baek;Rhim, Jong Guk
    • Journal of the Korean Institute of Gas
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    • v.24 no.3
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    • pp.33-39
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    • 2020
  • In general, in a batch reaction process in which products are made using flammable liquids, splash filling is used to clean the walls of the reactor by spraying flammable liquids, which are raw materials used for product, during cleaning of the reactor after work. During this process, mist of flammable liquid is generated, the lower limit of explosion is lowered, and fire·explosion may occur due to discharges caused by various types of complex charges, such as flow charge, collision charge, and ejection charge. Therefore, based on the recent accident case, to identify the risk when working in the form of splash filling with toluene in a batch process and perform an explosion impact analysis using the TNT equivalent method After that, we will analyze the accident results and suggest preventive measures such as constant purge system, improvement of cleaning method, and use of tantalum to prevent such accident.

New Collaborative Filtering Based on Similarity Integration and Temporal Information (통합유사도 함수의 이용과 시간정보를 고려한 협업필터링 기반의 추천시스템)

  • Choi, Keun-Ho;Kim, Gun-Woo;Yoo, Dong-Hee;Suh, Yong-Moo
    • Journal of Intelligence and Information Systems
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    • v.17 no.3
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    • pp.147-168
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    • 2011
  • As personalized recommendation of products and services is rapidly growing in importance, a number of studies provided fundamental knowledge and techniques for developing recommendation systems. Among them, the CF technique has been most widely used and has proven to be useful in many practices. However, current collaborative filtering (CF) technique has still considerable rooms for improving the effectiveness of recommendation systems: 1) a similarity function most systems use to find so-called like-minded people is not well defined in that similarity is computed from a single perspective of similarity concept; and 2) temporal information that contains the changing preference of customers needs to be taken into account when making recommendations. We hypothesize that integration of multiple aspects of similarity and utilization of temporal information will improve the accuracy of recommendations. The objective of this paper is to test the hypothesis through a series of experiments using MovieLens data. The experimental results show that the proposed recommendation system highly outperforms the conventional CF-based systems, confirming our hypothesis.