• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.1
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• pp.61-68
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• 1994

Neglecting distant zones in the computation of geoidal heights using Stokes'formula give rise to some truncation errors. The GRS80 Korean Gravimetric geoid Model 1993(KGM93) of the South Korea region was implemented, in this paper, using a combination of satellite-derived GEM-T2 gravity and terrestrial gravity data. A spherical cap size of 30 degree is used on the integration and the truncation error is compensated to the free-air geoid. The results of this study show that the accuracy of the KGM93-C has one meter level.

• Journal of Korea Foundry Society
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• v.3 no.2
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• pp.83-91
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• 1983

In this paper analytical and numerical methods fur analysis of solidification of castings are described, and the matrix method, one of numerical method, where the nodal point is designated on the element boundary was adapted. The cooling curve obtained by experimental values, when cast steel (0.29%C. 0.62%Si) was poured into $CO_2$ mold, is compared with that of computed values by exploiting computer (V77-600 Data Proceeding System, UNIVAC). The computed value is nearly approximation to the experimental. But the computed value shows a tendency that is a little higher than the experimental in solid-liquid coexisting temperature ranges and much lower than the experimental after solidification. It is considered to result from the lacks and difficulties of ultimately appropriate adaptation of various physical properties and also air cap between castings and mold.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.47-52
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• 1999

Theoretical and experimental studies on burr formation and deburring in many manufacturing processes have been actively pursued. Though micro-drilling has become more important in the production of precision parts such as PCB, air bearing, camera and nozzle, most studies on drilling burr formation have focused on the conventional drilling process. This paper describes burr formation process and the effect of cutting conditions such as spindle speed, feedrate and drilling depth per one step on burr formation in drilling A6061 with drills of diameter 1.0mm and 0.6mm. Experimental results showed that burr with cap were formed at relatively low feedrates, while petal burrs with several large burr fragments were formed at high feedrates. Burr height appeared to increase at the hight feedrates and lower spindle speeds. The effect of final cutting depth on burr height was negligible.

• Current Applied Physics
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• v.18 no.11
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• pp.1375-1380
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• 2018

Atmospheric-pressure plasma has a great potential in many applications due to its simplicity rather than low pressure plasmas. In material processing, biomedical applications, and many other applications, the input power, gas flow rate, and the geometry of electrode have been mainly considered and studied as important external parameters of atmospheric-pressure plasma control. Besides, since the atmospheric-pressure plasmas are typically generated in an open air, the relative humidity is difficult to control and can change day by day. Therefore, the relative humidity cannot be ignored for plasmas. Thus, in this work, the atmospheric-pressure plasma jet was characterized by changing relative humidity, and it was found that the increase in electron density and OH radicals are due to Penning ionization between helium metastable and water vapors at higher humidity condition.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.561-571
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• 2005

To introduce an emissions trading system for GHG that currently have no reduction requirements, the following should be considered as priorities: eliciting the participation of the industrial sector and linking GHG emission trading systems to the emissions trading system (implemented from July 2007) that has become part of national policy with the enactment of the Special Act. Two directions can serve as viable alternatives in that regard. One is a baseline-and-credit method based on incentive auctioning. This has the advantage of inducing participation through economic incentives without a reductions commitment. The downside of this method is that it requires vast investments, as well as the fact that reaching an agreement between participants and the government to decide an objective baseline is difficult. On the other hand, the cap-and-trade method set forth in the Special Act is attractive in that it can be integrated with the air pollutant emissions trading system, but it would be difficult to elicit the participation of the industrial sector in the absence of GHG emission reduction requirements. In the current situation, it would be preferable for the government to induce the participation of the industrial sector by devising a wide variety of incentives because taking part in the emissions trading system before reducing GHG emissions offers large incentives through learning by doing. The timing of GHG reduction commitments and emissions trading system implementation may be uncertain but their Implementation will be unavoidable. Thus the government needs to facilitate preparations for emissions trading of GHG in the future and continuously review its operation in integration with the air pollutant emissions trading system to maximize adaptation and teaming by doing effect in the industrial sector.

• Journal of Mushroom
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• v.15 no.1
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• pp.14-20
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• 2017

The oyster mushroom cultivation house typically has multiple layers of growing shelves that cause the disturbance of air circulation inside the mushroom house. Due to this instability in the internal environment, growth distinction occurs according to the area of the growing shelves. It is known that minimal air circulation around the mushroom cap facilitates the metabolism of mushrooms and improves their quality. For the purpose of this study, a CFD analysis FLUENT R16 has been carried out to improve the internal environment uniformity of the oyster mushroom cultivation house. It is found that installing a section of the working passage towards the ceiling is to maintain the internal environment uniformity of the oyster mushroom cultivation house. When all the environment control equipment - including a unit cooler, an inlet fan, an outlet fan, an air circulation fan, and a humidifier - were operated simultaneously, the reported Root Mean Square (RMS) valuation the growing shelves were as follows: velocity 23.86%, temperature 6.08%, and humidity 2.72%. However, when only a unit cooler and an air circulation fan operated, improved RMS values on the growing shelves were reported as follows: velocity 23.54%, temperature 0.51%, and humidity 0.41%. Therefore, in order to maintain the internal environment uniformity of the mushroom cultivation house, it is essential to reduce the overall operating time of the inlet fan, outlet fan, and humidifier, while simultaneously appropriately manage the internal environment by using a unit cooler and an air circulation fan.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.111-116
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• 2011

Three-dimensional finite element analyses have been performed to improve the durability of bulkhead. To keep pace with design changes and concentrate on regions of interest, SUBMODEL technique in ABAQUS was used for analysis. An analysis was conducted with following load cases: 1) Cap press-fit, 2) Bearing crush, 3) Bolt assembly, 4) Hot assembly, 5) Firing load, 6) Alternating firing load, 7) 2nd hot assembly. Fatigue analysis was done using commercial software FEMFAT and fatigue factors at the interested regions such as bolt tip area, counter bore, breathing hole, honing clearance were calculated and compared to aid design validation. Finite element modeling in the area of thread engagement used a simple constraint equations. Increasing bolt length, to a minimum of 39 mm above joint face gives a better fatigue resistance to the bulkhead. Breathing hole helps not only circulate the air in the crankcase but also fatigue resistance of bulkhead by relieving the stress at the critical locations.

• Korean journal of food and cookery science
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• v.26 no.6
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• pp.840-847
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• 2010

In this study, we identified the volatile compounds of Artemisia princeps Pampan. cv. ssajuari (ssajuarissuk) essential oils and analyzed changes in the contents of volatile compounds under four different storage conditions, such as exposure to air at $20^{\circ}C$ and $40^{\circ}C$. Sixty-five volatile compounds consisting of 6 monoterpene hydrocarbons, 23 oxygenated monoterpenes, 16 sesquiterpene hydrocarbons, 6 oxygenated sesquiterpenes, 1 diterpene, 6 benzene derivatives, and 7 non-isoprenoid compounds were identified on the basis of their mass spectra characteristics and retention indices from original ssajuarissuk essential oils. Identified compounds constituted 90.56% of the total peak area. Borneol (10.29%) was the most abundant compound in the original ssajuarissuk essential oils, followed by 1,8-cineole (9.06%), viridiflorol (8.99%), spathulenol (8.73%), $\alpha$-thujone (5.28%), and camphor (4.39%). After six months storage at $40^{\circ}C$ with the cap opened for 3 min everyday, the total amount of volatile compounds in essential oil as determined by the percentage peak area decreased by 84.93%. The total levels of cis-sabinene hydrate, camphor, 4-terpineol, humulene oxide, $\beta$-caryophyllene oxide, and caryophyllene alcohol increased significantly. For ssajuarissuk essential oils stored under experimental conditions, changes in the contents of volatile compounds in essential oils were accelerated by temperature and contact with the atmosphere.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.481-487
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• 2009

The compositional changes of wormwood (Artemisia princeps var. orientalis) essential oils were studied under 4 different storage conditions i.e., being exposed to air at 20 and $40^{\circ}C$. Sixty-four volatile compounds consisting of 24 terpene hydrocarbons, 18 alcohols, 11 ketones, 6 esters, 1 aldehyde, 2 hydrocarbons, and 2 oxides were identified on the basis of their mass spectra characteristics and retention indices in original wormwood essential oils. Identified compounds constituted 80.53% of the total peak area. Borneol (12.13%) was the most abundant compound, followed by $\alpha$-thujone (8.66%), T-cadinol (6.67%), and 1,8-cineole (6.21%) in original wormwood essential oils. Under the condition of $40^{\circ}C$ of temperature with the cap being opened for 3 min everyday respectively during 6 months of storage, the total amount of functional groups in essential oil determined by peak area percent were decreased by 79.45%, at most. The total level of monoterpene hydrocarbons decreased markedly in the aerobic condition and high temperatures. Whereas the total level of esters increased significantly. Wormwood essential oils were stored in experimental conditions, with the changes in the volatile compounds of essential oils being accelerated by high temperatures and contact with the atmosphere.

• 연구논문집
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• s.28
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• pp.73-87
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• 1998

A pneumatic control system of compressed air as a working fluid has a variety of advantages such as low price, high respondence, non-explosion and good control performance and thus has many applications in the field of automobile, electronic and semiconductor industry. However, it has a difficulty in contolling a precise position due to quick response of system and compressibility of working fluid and. in particular, shock stress may occur due to an external load, resulting in fracture of a cylinder cap unless cushion device is equipped in the linear actuator. To avoid this, a cushion device should be installed for damping effect of the external load and the supply pressure as well as for decreasing shock stress and vibration caused by high speed rotation. Previous studies include dimensionless analyses and computer simulations of cushion capability and experiments of horizontally-mounted cylinder performances. A new attempt is experimentally made in this study using a vertically-mounted cylinder under an operation condition of 4, 5 and 6 (bar) as supply pressure and 40, 70 and 100 (kgf) as external load. It turns out that the cushion pressure is mainly a function of the external load rather than the supply pressure. The cushion characteristics was also revealed in the meter-in circuit.