• Journal of Environmental Science International
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• v.11 no.6
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• pp.507-517
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• 2002

Cheeka Peak is a unique site for monitoring the background chemistry and aerosol contents of pristine marine air at mid-latitude. During long-range onshore winds that occur frequently throughout the year, it is predicted to have the cleanest air in the northern hemisphere. Measurements of CO and O$_3$were conducted at Cheeka Peak Observatory(CPO) on the northwestern tip of Washington state, USA during March 6 ∼May 29, 2001. The data have been segregated to quantify the mixing ratio of these species in the Pacific marine atmosphere. Also the marine air masses were further classified into four categories based on 10-day backward isentropic trajectories; high, mid, and low latitude and those which had crossed over the Asian industrial region. The diurnal variation of CO and O$_3$at CPO showed a similar to tendency of background measurement site. When marine air mass flowed to CPO, CO concentration was lower and O$_3$was similar or higher than those of total data. The westerly flow from ocean, not easterly from continent occurred the high concentration of CO and O$_3$at CPO. Using the trajectory segregation of marine air mass, the comparison of concentration according to latitude calculated. the CO concentration of Asian trajectory was lower than other latitudes, O$_3$concentration was higher.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.86-87
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• 2005

The combustion characteristics of the D.I. diesel engine are largely dependent on the air-fuel ratio and the gas exchange process. The main factors are the shape of combustion chamber, fuel injection system, air flow inside the cylinder, intake air mass flow rate and so forth. Because these factors affect the combustion in a mutual and combined manner, it is very important to clearly understand the correlation of these factors in order to provide the combustion improvement plans. In this paper, we studied the performance and the gas exchange process of marine four-stroke engine using the engine cycle simulation. Also, we predicted briefly turbocharger engine matching.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.162-175
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• 2008

Gyeongju, which was the central city of the ancient civilization at Silla Kingdom, has various kinds of stone cultural properties. It is significantly important to preserve historical sources of Korea. However, recent air quality data measured in Gyeongju did not show good air quality level. In order to investigate variation of the concentration of the air pollutants with meteorological condition, an air quality monitoring and an aerosol sampling were conducted during the intensive monitoring period in Gyeongju. Impacts of the meteorological factors on the air pollutants were also analyzed based on the air mass pathway categories using HYSPLIT model and the local wind patterns using MM5 model. The prevailing air mass pathways were classified into four categories as following; category I affected by easterly marine aerosols, category II affected by northwesterly continental aerosols, category III affected by southwesterly continental aerosols, and category IV affected by northerly continental aerosols. The concentrations of the air quality standards were relatively lower during the fall intensive monitoring period. At that time, the easterly marine air mass pattern was dominated. The seasonal average mass concentration of $PM_{10,Opt}$, which optically measured at the monitoring site, was the highest value of $77.6{\pm}28.3\;{\mu}g\;m^{-3}$ during the spring intensive monitoring period but the lowest value of $20.1{\pm}5.3\;{\mu}g\;m^{-3}$ during the fall intensive monitoring period. The concentrations of $SO_2$ and CO were relatively higher when the air mass came from the northwestern continent or the northern continent. The concentrations of ${SO_4}^{2-}$ and ${NO_3}^-$ increased under the northwesterly continental condition. It was estimated that the acidic aerosols were dominated in the atmosphere of Gyeongju when the air mass came from the continental regions.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.239-244
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• 2006

As an effective means to convey crushed materials from seabed to onboard ship, air-lift pump provides a reliable mechanism due to its simple configuration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance through analysis program based on the gas-liquid two-phase flow in circular pipes. It is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.252-258
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• 1999

As an effective means to convey crushed materials from seabed to on board ship and to raise hazardous or abrasive liquids air-lift pump provides a reliable mechanism due to its simple config-uration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newto-nian liquids. it is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates and furthermore attachment of downcomer gives little effects on riser performance the conveyed liquid flow rate increases with larger submergence rate.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.233-234
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• 2006

LNG is extremely cold, $-160^{\circ}C$ in its liquid state. When it vaporizes, returning to its natural state (re-vaporization), it cools its surroundings. This is cold energy. The manufacturing of liquid air is the first processes developed as the most effective utilization of LNG cold. In this paper, adopting the LNG cold process for manufacturing liquid air was developed and analysed. The result showed that as the higher air pressure and adapting nitrogen precooling, liquefaction rate and cumulative mass was increased.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.687-694
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• 1999

This study was conducted to develop new drying process for automatic control and marine engi-neering system. Air-water tests were carried out to investigate dryer performance. The dispersed flow in he dryer test apparatuses was also simulated by using a numerical code which solves the Dittus-Boelter equation for continuous liquid phase and the Reynolds equation of droplet motion for continuous liquid phase and the Reynolds equation of droplet motion for dispersed phase to predict droplet removal efficiency. Proper conditions for dehumidification were optimized by response ambient conditions. When the selected indexes were constrained in the range of 85-98% moisture content above $15^{\circ}$ and more than mass flow rates of moist air 750kg/h. The numerical results were compared with the experimental data pertaining to the removal effi-ciency at chamber stage and overall pressure drop along concentric tubes Good agreement was obtained as for the efficiency while relatively poor agreement was obtained for the relative humidity. The results also showed that the efficiency depended strongly on the relative humidity at the inlet condition which indicated the importance of estimating the heat exchanger length. Effects of some design parameters in both removal efficiency and breakthrough onset condition are discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1195-1202
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• 2004

In this paper an experimental study was investigated for two-phase flow distribution in compact heat exchanger header. A test section was consisted of the horizontal bottom dividing header($\phi$: 5 mm, L: 80 mm) and 10 upward circular mini channels ($\phi$: 1.5 mm, L: 850 mm) using an acrylic tube. Three different types of tube intrusion depth were tested for the mass flux and inlet mass quality ranges of 50 - 200 kg/$m^2$s and 0.1 - 0.3, respectively. Air and water were used as the test fluids. The distribution of vapor and liquid is obtained by measurement of the total mass flow rate and the calculation of the quality. Two-phase flow pattern was observed, and pressure drop of each channel was measured. By adjusting the intrusion depth of each channel an uniform liquid flow distribution through the each channel was able to solve the mal-distribution problem.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.701-706
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• 2005

Pipes, tubes. and tubular sections with external transverse high fins have been used extensively for heating cooling, and degumidifying air and other gases. This work was performed to investigate an air side heat transfer charactieristics of minichannel with tension wound transverse fin. This estimate was confirmed conversion heat capacity the air side surface area enlargement and heat transfer charactieristics performed available inlet tube side hot water mass flux or outlet tube side air frontal air velocity. The most suitable tension wound transverse finned minichannel was measured extremely low in air side pressure drop and fin effectiveness $3.3\~4.4$. The pressure drop $0.9\~2.8Pa$ was ranged frontal air velocity $0.5\~1.2m/s$. It is also appeared that heat transfer in air side could be better conversion heat area which has been increased $330\%$ of heat capacity compared with the bare tube.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.3
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• pp.347-357
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• 2011

The TSP aerosols were collected at Gosan site of Jeju Island between 2003 and 2007, and their aerosol components were analyzed to examine the variations of chemical compositions with the corresponding pathways of inflowing air parcels. According to the comparison of seasonal aerosol compositions, the soil-originated components showed remarkably high concentrations during spring season. On the other hand, the concentrations of anthropogenic components were somewhat high in spring and summer seasons, but low in fall season. Based on the comparison of TSP compositions in relation to the pathways of inflowing air mass, the concentrations of anthropogenic components (nss-$SO_4^{2-}$, S, $NO_3^-$), soil-originated components (nss-$Ca^{2+}$, Al, Fe, Ca), and the heavy metals (e,g., Mn, Zn, Cr, Pb, Cu, Cd, etc.) have relatively increased with the air mass moving from China continent into Jeju area. Meanwhile, the marine-originated components showed an increasing trend with the air mass coming from North Pacific Ocean. In the seasonal and sectional comparison, the nss-$SO_4^{2-}$, $NO_3^-$, nss-$Ca^{2+}$, and Al showed comparatively high concentrations when the air mass moved from China continent during all seasons. Especially, the $NO_3^-$, nss-$Ca^{2+}$, and Al concentrations were somewhat high when the air mass moved from Korean Peninsula during summer season. It was also recognized that the Na+ concentration were high, when the air mass moved from Pacific Ocean through all seasons.