• 수산해양기술연구
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• 제50권4호
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• pp.427-434
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• 2014

Although ex situ target strength (TS) measurements using dual- and split-beam systems have become the primary approach of estimating fish abundance, theoretical model estimation is a powerful tool for verifying the measurements, as well as for providing values when making direct measurements is difficult. TS values for 20 samples of live bambooleaf wrasse (Pseudolabrus japonicus) whose target length (TL) ranged between 13.7 and 21.3 cm were estimated theoretically using the Kirchhoff-ray mode model, and the TS values for 18 live fish samples were additionally measured at ${\sim}0^{\circ}$ tilt angle to the swimming aspect using a tethered method at a frequency of 120 kHz to verify the theoretical values. The digitizing intervals used to extract the fish body and swim bladder morphology in the X-ray photographs significantly affected the calculated TS patterns, but variations based on the speed of sound and density ratio values for the general range of fish flesh were relatively small (within 1 dB). Close agreement was observed between the measured and theoretical TS values, and the correlation between the average TS and body length of the fish could be calculated accurately as <$TS_{120kHz}$>= 20logTL (cm) -71.6 using the theoretical method.

• 상하수도학회지
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• 제22권6호
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• pp.705-714
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• 2008

Three Mesh Screenning Reactors (MSRs) were operated in three different modes to investigate the effect of the mesh opening size and the filtrate flux on the removal of particulate matters and the production of soluble organic matters. The mesh opening size was $82{\mu}m$ (Mode 1), $61{\mu}m$ (Mode 2) and $38{\mu}m$ (Mode 3), respectively, and each mode has three different filtrate flux; $0.47m^3/m^2/d$, $0.95m^3/m^2/d$ and $1.42m^3/m^2/d$, respectively. TSS removal efficiency of mode 1, 2, and 3 fed with 191 mgTSS/L was 27%, 36%, and 60%, respectively. The SCOD concentration of 91mg/L in influent for the mode 1, 2, and 3 increased to 117 mg/L, 127 mg/L, and 155 mg/L, respectively. For the all MSRs, there was no significant effect of filtrate flux on the removal of particulate matters and the production of soluble organic matters. However, the mesh opening size greatly affected the removal of particulate matters and the production of soluble organic matters in wastewater. Three parallel A2O processes consisting of anaerobic, anoxic and aerobic reactors maintaining mixed liquor suspended solids (MLSS) of 3,000 mg/L were operated to investigate the effectiveness of MSR on the removal efficiencies of the organic matters, nitrogen, and phosphorus; MSR influent was introduced to System 1 (183 mgTSS/L, 324 mgTCOD/L, 87 mgSCOD/L, 45.2 mgTKN/L, and 6.6 mgTP/L) and MSR efluent was introduced to System 2 and 3(72 mgTSS/L, 289 mgTCOD/L, 141 mgSCOD/L, 40.2 mgTKN/L, and 4.2 mgTP/L). HRTs of the anaerobic reactors in systems 1, 2 and 3 were 1 h, 1 h and 0.6 h, respectively and anoxic reactors were 2 h in all systems. HRTs of the aerobic reactors in systems 1, 2 and 3 were 5 h, 3 h and 3 h, respectively. TSS concentration in effluent of both system 2 and 3 is about 8 mg/L and lower than that of system 1 effluent. Despite higher TCOD loading and SCOD loading, both Systems 2 and 3 had a greater TCOD and SCOD removal efficiency at 91% and 92% than System 1 was at 88% and 82%, respectively. The nitrification efficiency for system 2 was greater than observed for System 1 (99% verses 97%). The denitrification efficiency for systems 1, 2 and 3 was 78%, 88% and 87%, respectively. System 2 and 3 showed about 12% higher TN removal efficiency than system 1 (85% verses 73%). The effluent TP concentration for system 2 was less than observed for system 1 and 3.

• 통상정보연구
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• 제6권1호
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• pp.3-23
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• 2004

Since the mid-1980's, strategic alliances are dominantly hailed as an effective growth and survival strategy in the era of international market and multinational corporation. There are a number of reasons for this phenomenon. there is an increasing globalization of markets in an ever-widening band of industries, together with the development of global technologies that makes production cycles shorten and the ever-increasing demand for investment resources and information to cope with the changing environment. The purpose of this study is to investigate the determinants of corporation information system in strategic alliance mode, and to analyze the main factors which are affecting the choice of strategic alliance mode by Korean firms. This study can also contribute theoretical and practical suggestive points in relation to strategic alliance operations. However, it also has limits as an exploratory study due to lacks of prior studies and proper methodologies and so on. Accordingly, the phenomenon of international strategic alliances call for further studies on casual relationships between main factors and variables in this field.

• Journal of Preventive Medicine and Public Health
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• 제38권3호
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• pp.241-251
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• 2005

There has been an enormous increasing trend of widening gap of social inequalities since economic crisis at the end of 1997 in Korea. Since then, Korean society has deteriorated in economic and social conditions; the unemployment rate, temporary or casual workers and absolute poverty have increased. This paper presents the origin of inequalities in work and health in Korea. The origin of inequalities in work begins with the relationship between the capitalist and labourers in the capitalist mode of production. The conception and execution are dissolved in the work process in the capitalist mode of production. Thus, captitalists become control over ther labour process from workers. An alienation of the work process from the workers. The distribution of work is the majour source if inequalities in many countries as well as Korea. This paper presents the increasing tendency of unhealthy states such as mortality, early death, morbidity, physical work load, workplace injury amongst the under-privileged: ordinary workers, unemployed people, casual workers and socially deprived people in Korea.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2531-2533
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• 2001

This paper describes a low noise and high efficiency analog-digital switching mixed mode battery charger for production facilities of Li-Ion batteries. The requirements for battery chargers for production facilities are very strict. The accuracy of output voltage and output current should be below 0.1% with very low ripple current. Therefore analog type linear regulators are widely used for battery charger in spite of their inefficiency and bulkiness. We combined linear regulator as a voltage source with digital switching converter as a dependent current source. Low current ripple and high accuracy are obtained by linear regulator while high efficiency is achieved by digital switching converter. Experimental results show that proposed method has 0.1% ripple and 90% efficiency at an output current of 1A for a battery voltage of 4V.

• 한국정밀공학회지
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• 제18권10호
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• pp.161-167
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• 2001

This paper presents an approach to nonlinear engine idle controller and intake manifold absolute pressure(MAP) observer based on mean torque production model. A stable engine idle speed is important in that the unstable engine Idle mode can make engine to drooping or stall state. A sliding fuzzy controller has been designed to control engine idle speed under load disturbance. A sliding observer is also developed to estimate the intake manifold absolute pressure and compared with the actual MAP sensor value. The sliding mode observer has shown good robustness and good tracking performance. The inputs of sliding fuzzy controller are the errors of rpm and MAP. The output is a duty cycle(DC) for driving a idle speed control valve(ISCV).

• 한국자동차공학회논문집
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• 제5권2호
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• pp.94-110
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• 1997

In the present study, a mean torque predictive model has been proposed and experimentally validated. It includes induction air mass model, fuel delivery model and mean production mode. Air induction and fuel delivery model considering dynamic behaviors of air induction and fuel delivery were proposed to predict the air-fuel ratio excursions under transient condition. Torque function model reflects thermal efficiency, volumetric efficiency, friction and effect of spark timing. In the spark timing model, knock limit and acceleration retard are included. Experiments were carried out to validate the simulation model for the step changes of throttle at constant engine speed. The results show reasonable agreements between simulation and experiment at fully warmed condition. Using this model, fueling strategies are varied with fast throttle open and it can predict air-fuel ratio excursion and IMEP.

• 한국미생물·생명공학회지
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• 제22권3호
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• pp.304-308
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• 1994

A suitable culture method and bioreactor type for itaconic acid production were chosen by comparing the maximal concentration of itaconic acid produced in various systems. In batch culture, the maximal concentration of itaconic acid produced in a bubble column reactor was about 5% greater than that produced in stirred-tank or external-loop airlift reactor. These results were thought to be due to lower shear force and higher mass transfer efficiency in a bubble column reactor in comparison with other reactors. Moreover, the fed-batch mode in a bubble column was found to be a suitable one, producing about 25% higher concentration of itaconic acid compared to batch mode.

• 한국환경보건학회지
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• 제32권5호
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• pp.499-505
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• 2006

Bioventing efficiency was compared in a continuous and an intermittent(6hr injection and 6hr rest) air injection mode. Two lab-scale columns which packed with 5 kg of soil artificially contaminated by diesel oil were operated. The columns were maintained at the $25^{\circ}C{\pm}2.5$ in order to minimize the effect of exterior temperature variation. The flow rate of air injection mode were maintained constantly at the flow rate of 10 ml/min. The moisture of the columns was stably maintained at $60{\sim}80%$ of field capacity. The nutrient compounds were added to make C:N:P ratio as 100:10:l. The continuous and intermittent injection modes showed 67.56% and 69.63% reduction of initial TPH concentration during 90 days, respectively. Two venting modes showed similar results in the analysis of the trends of the hydrocarbon utilizing bacterial counts for operating periods. The carbon dioxide production rate of the continuous injection mode was higher than that of intermittent injection mode. The loss of diesel oil by volatilization in the continuous and intermittent injection modes were about 5% and 1%, respectively. The lower volatilization loss in the intermittent injection mode suggested that the biodegradation of TPH in the intermittent injection mode was greater than that of the continuous mode. These results suggested that the intermittent injection mode is more efficient than the continuous venting mode.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2010년도 춘계학술대회
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• pp.67-73
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• 2010

This study began the study by instructing enterprises to change Batch Production into U-Line. This study suggested TPS U-Line building model process and applied it to some of their product line. By connecting concerned process elements into continuous operations. Outside orders were also switched to inside operations and executed in continuous operations, thereby about 100Km of transit distance became zero Km, Production lead Time was incredibly reduced. After all, 90% of Production Lead Time, 50% of handling fault, 3/4 of workers decreased and Productivity per Person enhanced which involves improving Batch Production into Continuous Production and applies it to the real world, so that small and medium enterprises can consult this study if the company is willing to make an improvement to their product line.