• Journal of the Korean Institute of Gas
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• v.21 no.2
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• pp.58-63
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• 2017

Currently, the safety monitoring process in a complex plant environment is proceeded by human. Sometimes, human error that may occur in a filed causes an severe problem. This paper introduces new method of safety monitoring system using sound information and fuzzy theory that is one of intelligent theories, in order to recognize the status of plant environment. In this paper, the filling station of high pressure gas will be used as a test plant. The result system will be widely applied for more complex plant environments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.9
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• pp.1217-1228
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• 1998

In order to elucidate the operational characteristics of rotating heat pipes, the internal flow patterns and heat transfer performance are investigated. Flow patterns and its transition are studied with various rotational speeds by visualizing flows established inside a rotating tube. To verify those results of analysis, 2 heat pipes of the same geometries but fill charge rates of 7, 30% were manufactured and submitted to operating tests. Comparison of experimental results on heat transfer rate show a fairly good agreement with the analytical results. The analysis reveals that the optimum charge ratio is ranged in 4~7% depending on the quantity of thermal loads. but the heat pipe with 7% of fill charge ratio reached dry-out limitation at heat flux of $q^{{\prime}{\prime}}=6.2kW/m^2$ lower than that of analytic results. Transition of flow regime was well related to the correlation by Semena & Khmelev on transient centrifugal Froude Number Frc. But hysteresis phenomenon was observed in transition of flow regime, when the rotational speed was stepwisely changed in the way to undergo 1 cycle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.498-503
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• 2017

There is no unusual difference in the initial viscosity of the propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material added with yellow iron oxide is faster than that of the addition of red iron oxide. Especially, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure. The initial viscosity was lowest at 71% of large particle/small particle ratio

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.725-733
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• 2002

In this study, the heat transport limitations of a two-phase closed thermosyphon were investigated. For the test, a two-phase closed thermosyphon ($L_t/: 600 mm,\;L_e:105mm,\;L_a:75mm,\;L_c:420mm,\;D_o:22.2mm,$ container: copper (inner grooved surface), working fluid: PFC ($C_6F_14$) was fabricated with a reservoir that can change the fill charge ratio. The following was imposed as the factors on the heat transport limitations of a two-phase closed thermosyphon. 1) Fill charge ratio of the working fluid. 2) Tilt angle of the longitudinal axis. From tile experimental data, some results were obtained as follows. When the fill charge ratio was relatively small ($\psi$20%), the heat transport limitation occurred about 100W by dry-out limitation. However over 40%, it shelved nearly constant value (500 W) by flooding limitation. The heat transport limitation according to the tilt angle increased smoothly until the tilt angle was $60^{\circ}$,/TEX>, after then decreased slowly.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.123-134
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• 1999

A new forming technology has been developed to fabricate near-net shape components by using aluminum alloys with globular microstructure. The estimations of filling characteristic in the forging simulation with arbitrarily shaped dies of SSM are calculated by finite element method with proposed algorithm. The proposed model and various boundary conditions for arbitrarily shaped die are investigated with the coupling calculation between the liquid phase flow and the solid phase deformation. The simulation processes with arbitrarily shaped dies are performed on the isothermal conditions and axisymmetric problems. To analyze the forging process simulation with SSM, new stress-strain relationship for semi-solid behaviour is described, and forging the liquid flow. Furthermore, For the purpose of getting net shape of SSM, it is important to be obtain a solid fraction in forging process with arbitrarily shaped dies. To produce a automotive part which have good mechanical properties, the filling pattern in accordance with die velocity and solid fraction distribution has to be estimated for arbitrarily shaped die.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.352-356
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• 2006

As a basic study to develop heating panel, the purpose of this study was to know possibility as a floor heating panel. We investigated working conditions and performance of pulsating heat pipe. Tests were conducted under the next conditions; Working fluid were R-22 and R-134a, charging ratio 40% and 50%, temperature of inlet water $60^{\circ}C$ and $70^{\circ}C$, flow rates $1{\sim}3kg/min$. The experimental results indicate that the pulsating heat pipe charged 50% showed better performance than 40%, R-22 is more suited to the working fluid than R-134a, and it has a possibility which can be applied to floor heating panel using a pulsating heat pipe.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.2
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• pp.95-105
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• 1973

Sink (grain)-filling rates of IR667 line (Suwon 213 and 214) and local leading varieties (Jinheung and Paldal) were investigated in relation to sink-source ratio, sink-source distance, forms of photosynthates, and weather factors. The results are as follows. 1. IR667 line have higher maximum filling rate (g. grain/day. ear) and shorter duration to reach maximum filling rate than local varieties. The curve pattern of sink-filling rate was high and steep type in IR667 line and low and broad type in local varieties. 2. Weather factors seem to give little effect on the curve pattern of sink-filling rate. 3. The functional sink-source distance (actual sink-source distance multiplied by the contribution rate of leaf for grain production) was shorter in upper leaves (flag and 2nd leaf) for IR667 line, the upper leaf-dependent type in grain production, and was longer in lower leaves (3rd and 4th) for local varieties, the lower leaf-dependent type. Specially short first internode from top may contribute to the upper leaf depencency of IR667 line. 4. According to free sugar-starch ratio (sugar/starch) in the culm and leaf sheath IR667 line could be classified as the high sugar type and the local varieties as the high starch type. The ratio of transportable form (sugar) to non transportable photosynthate (starch) seems to relate with sink-filling rate. And high sugar type is expected to have higher efficiency for grain production in view of energy balance. 5. A hypothesis that the higher in the uniformity within the series of productive structure the more efficient in grain production is proposed and discussed in relation to productivity. 6. According to the pattern of percent nutrient retention of each leaf blade IR667 showed the central retention type and Jinheung showed the apical retention type and each retention type appears to be a cause of each canopy conservation pattern. 7. From the content and percent distribution of nutrient in various organ IR667 could be classified as the leaf sheath dominant type and Jinheung as the leaf blade dominant type. 8. The fact that the greater the percent translocation of nutrient into grain the greater the percent nutrient retention in leaf blade was held between nitrogen and phosphorus within a variety and between varieties within a nutrient (N, P or K).

• KSBB Journal
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• v.18 no.3
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• pp.234-238
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• 2003

Biofilm process is preferred to activated sludge process in small domestic wastewater treatment plant because of its simplicity in operation and maintenance. Column reactor filled with waste ceramics and with waste plastics was used to remove pollutants in restaurant wastewater. COD removal at 18 hours of hydraulic retention time (HRT) gave 93.7%, COD removal during the experimental period, where maximum COD removal was observed. Under same condition, average removal of total nitrogen and total phosphorus were 82.3% and 25.9%, respectively Organic and nitrogen were efficiently removed with the HRT of 18 hours or more.

• Economic and Environmental Geology
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• v.22 no.4
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• pp.381-393
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• 1989

Hydrogeological modelling was performed to evaluate groundwater flow system in Igsan Area. The study area extends over $790km^2$. The geology consists of Jurassic Daebo granite and gneissose granite and Precambrian metamorphic rocks. The capability of pumping yield is the highest in gneissose granite region among them due to comparatively thick weathered zone with thickness ranging from 10m to 25m. The Colorado State University Finite Difference Model was used for the model simulation. The model was divided into 28 rows and 31 columns with variable grid spacing. The model was calibrated under steady-state and unsteady-state conditions. In the steady-state simulation, the model results were compared with measured water table contours in September 1985 with determining hydraulic conductivities and net recharge rates during rainy season. Unsteady state simulation was done to know the aquifer response due to groundwater abstraction. The non- steady state calibration was conducted to determine the distribution and magnitudes of specific yields and discharge/recharge rates during dry season as matching water level altitudes in May 1986. The calibrated model was used to simulate water level vaiation caused by groundwater withdrawal and natural recharge from 1 October, 1985 until 30 September, 1995. The calibrated model can be used to groundwater development schemes on regional groundwater levels, but it cannot be used to simulate local groundwater level change at a specific site.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.377-383
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• 2007

In recent years the field application of high performance concrete has been increased to improve the quality and reliability of concrete structures. The mix design of the high performance concrete includes the 2 set-off mixture theory of mortar and coarse aggregate and that of paste and aggregate. The 2 set-off mixture theory of mortar and coarse aggregate has a problem of having to determine its value through repeated experiments in applying the rheological characteristics of mortar. The 2 set-off mixture theory of paste and aggregate has never been applied to high performance concrete since it doesn't take into account the relationship between optimum fine aggregate ratio and unit volume of powder nor does it consider the critical aggregate volume ratio. As the mixture theory of these high performance concretes, unlike that of general concrete, focuses on flowability and charge-ability, it does not consider intensity features in mix design also, the unit quantity of the materials used is determined by trial and error method in the same way as general concrete. This study is designed to reduce the frequency of trial and error by accurately calculating the optimum fine aggregate ratio, which makes it possible to minimize the aperture of aggregate in use by introducing the maximum density theory to the mix design of high performance concrete. Also, it is intended to propose a simple and reasonable mix design for high performance concrete meeting the requirements for both intensity and flowability. The mix design proposed in this study may reduce trial and error and conveniently produce high performance concrete which has self-chargeability by using more than the minimum unit volume of powder and optimum fine aggregate with minimum porosity.