• 한국패류학회지
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• 제28권3호
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• pp.277-291
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• 2012

Aquaculture is challenged by a number of constraints with future efforts towards sustainable production. Global climate change has a potential damage to the sustainability by changing environmental surroundings unfavorably. The damaging parameters identified are water temperature, sea level, surface physical energy, precipitation, solar radiation, ocean acidification, and so on. Of them, temperature, mostly temperature elevation, occupies significant concern among marine ecologists and aquaculturists. Ocean acidification particularly draws shellfish aquaculturists' attention as it alters the marine chemistry, shifting the equilibrium towards more dissolved CO2 and hydrogen ions ($H^+$) and thus influencing signaling pathways on shell formation, immune system, and other biological processes. Temperature elevation by climate change is of double-sidedness: it can be an opportunistic parameter besides being a generally known damaging parameter in aquaculture. It can provide better environments for faster and longer growth for aquaculture species. It is also somehow advantageous for alleviation of aquaculture expansion pressure in a given location by opening a gate for new species and aquaculture zone expansion northward in the northern hemisphere, otherwise unavailable due to temperature limit. But in the science of climate change, the ways of influence on aquaculture are complex and ambiguous, and hence are still hard to identify and quantify. At the same time considerable parts of our knowledge on climate change effects on aquaculture are from the estimates from data of fisheries and agriculture. The consequences may be different from what they really are, particularly in the temperature region. In reality, bivalves and tunicates hung or caged in the longline system are often exposed to temperatures higher than those they encounter in nature, locally driving the farmed shellfish into an upper tolerable temperature extreme. We review recent climate change and following environment changes which can be factors or potential factors affecting shellfish aquaculture production in the temperate region.

• 한국군사과학기술학회지
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• 제3권1호
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• pp.207-217
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• 2000

A fire fighting characteristic by a single evaporating droplet in the case of a fire of military enclosure space was studied experimentally. Transient cooling of solid surface by water droplet evaporation has been investigated through controlled experiments using a heated brass cylinder. Quantitative predictions of droplet evaporation time and in-depth transient temperature distribution in solid have been made. The particular interest was in the removal of thermal energy from the heated cylinder by evaporative cooling. A $10{\mu}1$ single droplet is deposited on a horizontal brass surface with initial temperatures in the range of $90^{\circ}C{\sim}130^{\circ}C.$ The results can be summarized as follows; Evaporating droplet was divided into three different configuration. Evaporation time was predicted as a function of initial surface temperature ($t_c=492.62-6.89T_{s0}+0.0248T_{s0}^2).$ The contact temperature was predicted as a function of initial surface temperature( $T_{i}$=0.94 $T_{s0}$+1.4), The parameter ${\beta}_o$ was predicted as a function of initial surface temperature( ${\beta}_0$ : 0.O0312 $T_{s0}+0.932$)>)>)

• KIEE International Transaction on Systems and Control
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• 제2D권2호
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• pp.78-91
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• 2002

In the thermal power plant, there are six manipulated variables: main steam flow, feedwater flow, fuel flow, air flow, spray flow, and gas recirculation flow. There are five controlled variables: generator output, main steam pressure, main steam temperature, exhaust gas density, and reheater steam temperature. Therefore, the thermal power plant control system is a multinput and output system. In the control system, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, strict control of the steam temperature must be maintained to avoid thermal stress. Maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature versus changes in fuel flow rate, difficulty of control of the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, and the fluctuation of inner fluid water and steam flow rates during the load-following operation. Up to the present time, the Proportional-Integral-Derivative Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on the characteristic comparison of the PID controller and the modified 2-DOF PID Controller (Two-Degrees-Freedom Proportional-Integral-Derivative) on the DCS (Distributed Control System). The method is to design an optimal controller that can be operated on the thermal generating plant in Seoul, Korea. The modified 2-DOF PID controller is designed to enable parameters to fit into the thermal plant during disturbances. To attain an optimal control method, transfer function and operating data from start-up, running, and stop procedures of the thermal plant have been acquired. Through this research, the stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Also, this paper addressed whether an intelligent tuning method based on immune network algorithms can be used effectively in tuning these controllers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1012-1015
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• 2003

Recently technologies have created new principle and theory but the PID control system remains its popularity as the PID controller contains simple structure, including maintenance and parameter adjustment being so simple. The adjust parameter of PID to achieve best response of process which be using time and may be error if user are not expert. Nowadays this problem was solved by develop PID controller which can analysis and auto tune parameter are appropriate with process which used principle of Ziegler ? Nichols but it are expensive and designed for each task. Thus, this paper proposes auto tune PID based on FPGA by use principle of Dahlin which maximum overshoot not over 5 percentages and do not fine tuning again. It have performance in control process are neighboring controller in industrial and simple to use. Especially, It can use various process and low price. The auto tune digital PID processor embedded on chip FPGA XC2S50-5tq-144. The digital PID processor was designed by fundamental PID equation which architectures including multiplier, adder, subtracter and some other logic gate. It was verified by control model of temperature control system.

• Advances in concrete construction
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• 제15권4호
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• pp.241-249
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• 2023

The unsteady mixed convection Casson type MHD nanofluid flow in the stagnation point with motile microorganism around a spinning sphere is investigated. Time dependent flow dynamics is considered. Similarity transformations have been employed to transfer the governing partial differential structure into ordinary differential structure. The impact of distinct parameters is examined via tables and graphs. The impact of rotational parameter (spin) on profiles of velocity profiles, temperature and concentration is revealed for unsteady mixed convection Casson type MHD nanofluid flow. It is observed that it is clear that rotational parameter has a great effect on non-dimensional primary velocity component but rotational parameter has a slight impact on non-dimensional secondary velocity component. The validity of the current investigation is authorized through comparing the existing outcomes with previous published literature.

• 동력기계공학회지
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• 제13권6호
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• pp.76-81
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• 2009

Thermal desorption systems are designed to remove organic compounds from solid matrices such as soils, sludges and filter cakes without thermally destroying them. It is a separation technology, not a destruction technology. Since it is a thermal process, there is a common belief that temperature is the only significant parameter to be monitored. While it is true that better removal efficiencies are usually achieved at higher temperatures, other factors must be considered. Since the process is governed by mass transfer, heating time and the amount of mixing are also key parameters in optimizing removal efficiency. Thermal desorption have been successfully used for just about every organic contaminant found to date. It has also been used to remove mercury. In the present study, the numerical simulation has been performed to investigate the characteristics of heat transfer of LTTD(low temperature thermal desorption). The commercial software, AMESIM was applied for analyzing the heat transfer process in the LTTD.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1537-1541
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• 2007

We injection molded a wedge type of plate with micro prizm patterns on its surface and investigated the fidelity of replication of the micro pattern depending on the process parameter such as mold temperature, melt temperature, injection rate or packing pressure. The size of the size of the $90^{\circ}$ prizm pattern is $50{\mu}m$ and the size of the plate is about 300㎜${\times}$200㎜. The thicknesses are 2.6㎜. and 0.7mm at each edge of the wedge type of plate. The fidelity of the replication turned out quite different according to the process parameters and location of the patterns on the plate. We measured the cavity pressure and temperature in real-time during the molding to analyze the effect of the local melt pressure and temperature on the micro pattern replication.

• 대한기계학회논문집A
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• 제31권2호
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• pp.160-165
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• 2007

To predict long-term creep life from short-term creep life data, various parametric methods such as Larson-Mille. (L-M), Orr-Sherby-Dorn (O-S-D), Manson-Haferd (M-H) parameters, and a Minimum Commitment Method (MCM) were suggested. A number of the creep data were collected through literature surveys and experimental data produced in KAERI. The polynomial equations for type 316LN SS were obtained by the time-temperature parameters (TTP) and the MCM. Standard error (SE) and standard error of mean (SEM) values were obtained and compared with the each method for various temperatures. The TTP methods showed good creep-life prediction, but the MCM was much superior to the TTP ones at $700^{\circ}C$ and $750^{\circ}C$. It was found that the MCM were lower in the SE values when compared to the TTP methods.

• Design & Manufacturing
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• 제11권2호
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• pp.15-19
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• 2017

Carbon fiber reinforced plastic (CFRP) is applied as structural material. CFRP is excellent in plane strength / stiffness and don't haves rust. Lightweight, rigid and robust at the same time as transportation material. Aluminum alloy and reinforcement material The application is increasing rapidly. In this study, the prototype of a semi - Monocoque structure frame, Longeron, Stringer, Skin of the aircraft, restraining the rigidity Clips of the aircraft was designated as the target product and the experiment was conducted. ln the experiment, (1) For CFRTP 3 points, data on heating, transfer, and cooling were measured using Thermo Couple, and optimum temperature required for flexible state was obtained. Heating was performed at a temperature 15% higher than the provided temperature. (2) By using a pneumatic press during molding, by dividing LH, center and RH according to the cooling time, thickness parameter of the target product due to the load is measured, and thickness control and time-deviations were analyzed and cross sections were observed with a low magnification microscope.

• 상하수도학회지
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• 제11권4호
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• pp.126-132
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• 1997

Trihalomethanes (THMs) are formed during the chlorination of waters containing precusors compounds, most commonly humic substances, changes in pH, TOC, temperature, precusor source and concentration chlorine dosage, bromide level and reaction time directly influence trihalomethane formation potential (THMFP) and kinetics. A standard THMFP experiment was conducted for each water under the following conditions ; $20^{\circ}C$, pH 7.4, reaction time of 48hr, TOC 5.7mgC/L. A series of kinetic experiments was conducted for each water to provide THM formation under varying conditions of reaction time, pH, temperature and TOC, chlorine dosage. The resultant mutiple parameter powre function predicts a THM which allows direct calculation of THM, is $[THM]=0.00039(pH-2.81)[TOC][Cl_2]^{0.321}\;t^{0.266}\;T^{0.286}$ Characteristics of raw water in advanced drinking water treatment pilot plant were, TOC levels ran from 4.42~6.84mgC/L, pH 7.2~7.8, temperature $7.0{\sim}18.4^{\circ}C$, UV-254 absorbance $0.057{\sim}0.85cm^{-1}$, THM levels ranged from 0.031~0.049mgC/L.