• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.6
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• pp.67-72
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• 2019

This study compared the theory of a culvert spacing and analytical results of the seepage flow for the subsurface drainage. i) If culvert spacing (Sc) is within 5 m, the unit drainage (q) is very larger; in contrast, if Sc is 5 m or more, there is very little drainage in the middle between drains. Therefore, the drain spacing should be within 5 m to ensure high drainage efficiency. ii) Since the planned culvert drainage increases linearly with the soil's permeability coefficient (k), k must be taken into account when determining the drain diameter by the planned culvert drainage. iii) As a result of analyzing the drainage performance of the absorbing culvert, the drainage performance is sufficient with the diameter of the corrugated drain pipe Dc = 50 mm at the length of the drain Lc = 100 m. iv) Therefore, if the drain spacing (Sc) is less than 5 m using the low-cost non-excavated drainage pipe method (${\Phi}50mm$ the corrugated drain pipe and fiber mat) rather than the conventional trench drain method (Sc > 10 m, Dc > 100 mm), uniform and high drainage efficiency can be ensured as well as low construction cost. v) The sub-irrigation+drainage culvert requires narrower drain spacing (Sc < 2-3 m) for irrigation. As a result of examining the condition of 35 mm in diameter (Dc) and 2~3 m in drain spacing, it is possible to apply the non-excavated drainage pipe method to the sub-irrigation+drainage culvert because drainage performance is sufficient at the drain length Lc = 50 m.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.4
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• pp.331-341
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• 2013

In the present work, the effect of the gate-to-drain capacitance ($C_{gd}$) on the noise performance of a symmetric tied-gate $In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}As$ double-gate HEMT is studied using an accurate charge control based approach. An analytical expression for the gate-to-drain capacitance is obtained. In terms of the intrinsic noise sources and the admittance parameters ($Y_{11}$ and $Y_{21}$ which are obtained incorporating the effect of $C_{gd}$), the various noise performance parameters including the Minimum noise figure and the Minimum Noise Temperature are evaluated. The inclusion of gate-to-drain capacitance is observed to cause significant reduction in the Minimum Noise figure and Minimum Noise Temperature especially at low values of drain voltage, thereby, predicting better noise performance for the device.

• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.82-88
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• 2013

There are the stirring test and drain test in the daily performance test to determine the thermal performance of a domestic solar hot water system. The drain test is a test that measures the discharge heating rate while drain the hot water from the top of the storage tank and supply the city water to the bottom of the tank. From the perspective of the user, this drain test is more effective than the stirring test. In this study, the thermal performance were compared through the drain test for a passive type and an active type domestic solar hot water systems consisting of the same storage tank and collectors. At this point, a passive type was used the horizontal storage tanks, and an active type was used vertical storage tank. In the drain test, when the hot water drained up to the reference hot water temperature, an active type which have vertical storage tank represents excellent daily performance than a passive type which have horizontal storage tank regardless of weather conditions. The reason for this is because the vertical storage tank is advantageous to thermal stratification in the tank. After the drain test, the residual heat for the horizontal storage tank was much more than the vertical storage tank, but in the next day the amount of discharged heat were less than the those of vertical storage tank neither. Thus, the solar water heating system which have horizontal storage tank should be adopted preheating control method rather than separate using control method when connected with auxiliary heat source device.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.155-162
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• 2016

A proton exchange membrane fuel cell (PEMFC) produces only water at cathode by an electrochemical reaction between hydrogen and oxygen. The generated water is transported across the membrane from the cathode to the anode. The transported water collected in water-trap and drained to the cathode within the humidifier outlet. If the condensate water is not being drained at the appropriate time, condensate water in the anode can cause the performance degradation or fuel efficiency degradation of fuel cell by the anode flooding or unnecessary hydrogen discharge. In this study, we proposed an optimization method of condensate water drain logic for the water drain performance and the water drain algorithm as considered the condensate water generating speed prep emergency case. In conclusion, we developed the water management strategy of fuel processing system (FPS) as securing fuel efficiency and operating stability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.451-466
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• 2003

Untethered nodes in mobile ad-hoc networks strongly depend on the efficient use of their batteries. In this paper, we propose a new metric, the drain rate, to forecast the lifetime of nodes according to current traffic conditions. This metric is combined with the value of the remaining battery capacity to determine which nodes can be part of an active route. We describe new route selection mechanisms for MANET routing protocols, which we call the Minimum Drain Rate (MDR) and the Conditional Minimum Drain Rate (CMDR). MDR extends nodal battery life and the duration of paths, while CMDR also minimizes the total transmission power consumed per packet. Using the ns-2 simulator and the dynamic source routing (DSR) protocol, we compare MDR and CMDR against prior proposals for power-aware routing and show that using the drain rate for power-aware route selection offers superior performance results.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.3
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• pp.26-31
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• 2006

Through the KOMPSAT program, Koreanization of thruster have been carried out successfully, but there are still many difficulties in Koreanization of most core parts of propulsion system. Because the development of core parts is essential to participate in the advanced nations, KARI has carried out development of Fill/Drain valve for propellant/pressurant supply of satellite, which has high possibilities to be koreanized, with Hanwha Corp.. This paper summarizes overall processes of development including design, manufacturing and test, and finally 4 sets of modules were successfully made. Also the satisfaction of performance requirements are verified through performance tests.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.69-74
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• 2016

In this study, we proposed an a-IGZO (amorphous In-Ga-Zn-O) TFT (thin-film transistor) with off-planed source/drain structure. Furthermore, two different electrode materials (ITO and Ti) were applied to the source and drain contacts for performance improvement of a-IGZO TFTs. When the ITO with a large work-function and the Ti with a small work-function are applied to drain electrode and source contact, respectively, the electrical performances of a-IGZO TFTs were improved; an increased driving current, a decreased leakage current, a high on-off current ratio, and a reduced subthreshold swing. As a result of gate bias stress test at various temperatures, the off-planed S/D a-IGZO TFTs showed a degradation mechanism due to electron trapping and both devices with ITO-drain or Ti-drain electrode revealed an equivalent instability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.157-157
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• 2008

As the minimum feature size of semiconductor devices scales down to nano-scale regime, ultra shallow junction is highly necessary to suppress short channel effect. At the same time, Ni-silicide has attracted a lot of attention because silicide can improve device performance by reducing the parasitic resistance of source/drain region. Recently, further improvement of device performance by reducing silicide to source/drain region or tuning the work function of silicide closer to the band edge has been studied extensively. Rare earth elements, such as Er and Yb, and Pd or Pt elements are interesting for n-type and p-type devices, respectively, because work function of those materials is closer to the conduction and valance band, respectively. In this paper, we increased the work function between Ni-silicide and source/drain by using Pd stacked structure (Pd/Ni/TiN) for high performance PMOSFET. We demonstrated that it is possible to control the barrier height of Ni-silicide by adjusting the thickness of Pd layer. Therefore, the Ni-silicide using the Pd stacked structure could be applied for high performance PMOSFET.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1581-1584
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• 2008

In this study, performance Assesment of the existing tunnel drain and higher permeable for the In-plane Test. Two separate simulation tests from geotexitile and Lightweight Foamed Mortar compare. perfomed:the one is the in-plane test and the other is the clogging phenomenon test. As a result, NATM Composite used to Ligheweight Foamed Mortar pemability 80%, more than existing tunnel drain. Also, clogging phenomenon test do low assesment more than existing tunnel drain geotextile.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.6
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• pp.457-461
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• 2009

In this paper, barrier height between Ni-silicide and source/drain is reduced utilizing Pd stacked structure (Pd/Ni/TiN) for high performance PMOSFET. It is shown that the barrier height is decreased by Pd incorporation and is dependent on the Pd thickness. Therefore, Ni-silicide using the Pd stacked structure is promising for high performance nano-cale PMOSFET.