• Korean Journal of Construction Engineering and Management
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• v.15 no.3
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• pp.31-37
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• 2014

"The Law of purchasing policy for market support of small and medium business" was legislated to support small and medium industry by expanding purchase and revised consistently for the activation. And then the government made the public construction direct purchase compulsory about design items designated by president on small and medium business based on this law. However, secureing quality, tardiness and field material staff's heavy duty were arisen from approximately 120 direct market purchase items. The legislative intent of law is in accord with Win-Win growth between major company and small and medium business. However material staff who works in the field based on this law has difficulties with material securing quality, JIT(Just In Time), cost push. This study reclassified procurement items of "the direct market purchase system" reasonably and then suggested performance criteria for evaluation. The suggested result will contribute to vatalize the direct market purchase system.

• Korea Trade Review
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• v.46 no.3
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• pp.135-149
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• 2021

This study analyzes the economic effect through the use of the RCEP direct transport rules, and suggests the necessacity of logistics efficiency and policy alternatives. The advantage of the hub network has been widely applied to the international logistics system, but there is a limit in the FTA logistics system in which goods must be directly transported between two contracting parties. Therefore, based on the new RCEP direct transport rules and the theoretical review on the possibility of an FTA logistics hub, FTA logistics efficiency improvement is estimated. This study quantitatively estimated the economic effect of direct transportation, unlike the previous studies, which were limited to the analysis of judicial precedents or surveys. GTAP model was used through five scenarios according to the impact of the RCEP tariff cut and the FTA logistics hub establishment in Singapore or Korea. As a result of the analysis, Korea's trade volume increased by 0.38% of exports and 1.63% of imports, and RCEP would increase exports by 0.27% and imports by 0.42%. In particular, the establishment of an FTA logistics hub (0.71%) was found to have a greater effect on the improvement of terms of trade than a tariff cut (0.12%), confirming the necessity of establishing an FTA logistics hub in RCEP. As a policy proposal, the institutional support of the customs authorities for the use of RCEP, the expansion of the free trade area where BWT traded cargo can be stored, and the establishment of a system for issuing back-to-back certificates of origin with approved exporters.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.172.1-172.1
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• 2010

In Jeju, underground air is used for heating greenhouse and fertilizing natural $CO_2$ gas by suppling directly into greenhouse. But greenhouse heating method by direct supply of underground air has several problems as like low temperature below $20^{\circ}C$ or high relative humidity over 90%. The underground air is inadequate in heating of crops such as mangos, oranges with the growing temperature over $20^{\circ}C$. Also if the relative humidity of greenhouse is kept with over 90%, diseases can strike almost of the crops. And also the ventilation loss becomes larger because the air pressure of inside greenhouse by direct supply of underground air is higher. In this study the heat pump system using underground air as heat source was developed and heating performance of the system was analyzed. Heating COP of the system was 2.5~5.0 and rejecting heat into greenhouse and extracting heat from underground air in this heat pump system were 46.5~31.4 kW, 34.9~20.9 kW respectively.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.821-827
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• 2001

As one of the advanced design features of the Korea next generation reactor, direct vessel injection (DVI) system is being considered instead of conventional cold leg injection (CLl) system. It is known that the DVI system greatly enhances the reliability of the emergency core cooling (ECC) system. However, there is still a dispute on its performance in terms of water delivery to the reactor core during the reflood period of a large-break loss-of-coolant accident (LOCA). Thus, experimental validation is under progress. In this paper, a new scaling method, using time and velocity reduced linear scaling law, is suggested for the design of a scaled-down experimental facility to investigate the direct ECC bypass phenomena in PWR downcomer.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.39-45
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• 2012

Today gasoline engines for vehicular application are not only faced with stringent emission regulation but also with increasing requirements to better fuel economy, while guaranteeing power density. The spray-guided type gasoline direct injection (GDI) engine has an advantage of improved thermal efficiency and lower harmful emissions. Centrally mounted high pressure injector and adjacent spark plug allow stable lean combustion due to the flexible mixture stratification. In the present study, the performance and emissions characteristics of developed spray-guided type GDI combustion system were evaluated at various excess air ratio conditions. The specific fuel consumption and nitrogen oxides ($NO_x$) emissions were reduced due to the achievement of stable lean combustion under flammability limit. Multiple injection strategy was not helpful to improve fuel consumption while further reduction of $NO_x$ emissions was possible.

• KIISE Transactions on Computing Practices
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• v.23 no.2
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• pp.134-139
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• 2017

The existing screen mirroring systems are vulnerable to packet loss and inefficient for mobile devices with limited energy capacity. To overcome these problems, we propose a packet loss robust and energy efficient screen mirroring system for mobile device. The proposed system employs systematic Raptor codes for a forward error correction method to mitigate the video quality degradation that is caused by packet loss over wireless networks. For the mobile device energy saving, the proposed system shapes the screen mirroring traffic and adjusts the Raptor encoding parameters. In this paper, the proposed system is fully implemented on single board computers and is examined in a real Wi-Fi Direct network.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6484-6487
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• 2013

This paper reports the direct controller for nonlinear plants using a neural network. The controller was composed of an approximate controller and a neural network auxiliary controller. The approximate controller provides rough control and the neural network controller gives the complementary signal to further reduce the output tracking error. This method does not place too much restriction on the type of nonlinear plant to be controlled. In this method, a RBF neural network was trained and the system showed stable performance for the inputs it has been trained for. The simulation results showed that it was quite effective and could realize satisfactory control of the nonlinear system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.97-104
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• 2011

This paper presents modeling and control for the emerging IGBT converter-based high-voltage direct-current system (IGBT-HVDC). This paper adds to the representation of the IGBT-HVDC system in the dq-synchronous reference frame and its decoupled control scheme. Additionally, since the IGBT-HVDC is able to actively support the grid due to its capacity to control independently active and reactive power production, a reactive power control scheme is presented in order to regulate/contribute to the voltage at a remote location by taking into account its operational state and limits. The ability of the control scheme is assessed and discussed by means of simulations using ahybrid power system, which consists of a permanent magnetic synchronous-generator (PMSG) based wind turbine, an IGBT-HVDC, and a local load.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1373-1392
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• 2017

WiFi Direct (WD) is a state of the art technology for a Device-to-Device (D2D) communication in 802.11 networks. The performance of the WD system can be significantly affected by some key factors such as the type of application, specifications of MAC and PHY layer parameters, and surrounding environment etc. It is, therefore, important to develop a system model that takes these factors into account. In this paper, we focus on investigating the design parameters of the PHY layer that could maximize the efficiency of the WD 802.11 system. For this purpose, a basic theoretical model is formulated for a WD network under a 2x2 Multiple In Multiple Out (MIMO) TGn channel B model. The design level parameters such as input symbol rate and antenna spacing, as well as the effects of the environment, are thoroughly examined in terms of path gain, spectral density, outage probability and Packet Error Rate (PER). Thereafter, a novel adaptive algorithm is proposed to choose optimal parameters in accordance with the Quality of Experience (QoE) for a targeted application. The simulation results show that the proposed method outperforms the standard method thereby achieving an optimal performance in an adaptive manner.

• Asia pacific journal of information systems
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• v.12 no.3
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• pp.45-70
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• 2002

This paper examines the role of distance learning self-efficacy, belief in one's capabilities of using a system in the accomplishment of web-based distance learning, in predicting user intention to use and performance of distance learning system. It used self-efficacy theory and technology acceptance model(TAM) to build a model that predicts relationships between antecedents to students' distance learning self-efficacy assessments and their behavioral and attitudinal consequences. The model was tested using LISREL analysis on the sample of 250 students who have worked with the Distance Learning System. The results indicated partial support for the conceptual model. In accordance with TAM, perceived usefulness had strong direct effects on intention to use and performance, while perceived ease of use had both direct and indirect effects on intention to use, but not performance. Distance learning self-efficacy had only direct effect on perceived ease of use to use. Computer experience was found to have a strong positive effect on distance learning self-efficacy, and computer anxiety had a negative effect on distance learning self-efficacy. Implications of these findings are discussed for researchers and practitioners.