• Journal of Power System Engineering
• /
• v.15 no.2
• /
• pp.37-41
• /
• 2011

This paper presents the capacity-control characteristics in an industrial cooler with a variable speed compressor. The inverter-type compressor is controlled by the rotational speed of the operational frequency. This type of the compressor performs the wide range of load compared to the on-off type. When the load of the system reduces, the rotational speed will be reduced. Thus, the system leads to the less power consumption and extends the longer durability of the compressor. With the variable rotational speed of the compressor the cooling capacity of the cooler is about 1.6-3.6 kW and the capacity control is about 40-100%. The system showed the highest efficiency when the rotational speed is about 45-70 Hz. The results can be used as the basic design data to control an industrial cooler.

• Journal of ILASS-Korea
• /
• v.15 no.3
• /
• pp.131-139
• /
• 2010

Gas motion within the engine cylinder is one of the major factors controlling the fuel-air mixing and combustion processes in diesel engines. In this paper, a special swirl-chamber is designed and applied to a DI (direct injection) diesel engine to generate a strong swirl motion thus enhancing gas motion. Compression, combustion and expansion strokes of this DI diesel engine with the swirl-chamber have been simulated by CFD software. The simulation model was first validated through comparisons with experimental data and then applied to do the simulation of the spray and combustion process. The velocity and temperature field inside the cylinder showed the influences of the strong swirl motion to spray and combustion process in detail. Cylinder pressure, average temperature, heat release rate, total amount of heat release, indicated thermal efficiency, indicated fuel consumption rate and emissions of this DI diesel engine with swirl-chamber have been compared with that of the DI diesel engine with $\omega$-chamber. The conclusions show that the engine with swirlchamber has the characteristics of fast mixture formulation and quick diffusive combustion; its soot emission is 3 times less than that of a $\omega$-chamber engine; its NO emission is 3 times more than that of $\omega$-chamber engine. The results show that the DI diesel engine with the swirl-chamber has the potential to reduce emissions.

• Korean Institute of Interior Design Journal
• /
• v.24 no.5
• /
• pp.78-86
• /
• 2015

Nowadays, there has been a trend about drinking coffee due to remarkable expansion of market, but the market is occupied by less franchise cafes having a lot of branches, and small private cafes are just few percentage. On other aspects, there will be a good effect of more active economy when private cafes are more active through this domestic situation of market which has the high rate of private business. Therefore, it is necessary to research design of fasade and especially fixed features on private cafes located in Busan Jeonpo cafe street by maketing of sensibility. firstly, there is the analysis about trends and features of fixed factors, and secondly, there is deep analysis about structural. and decorated factors. Furthermore, as a result of the analysis of similarities and differences, the variations in the design of private cafe will be understanded. whenever structural and decorated factors are balanced, for the design is more worthy, there will be formed basis of analysis in trends. In addition, the basic data research which includes anaysis and comparisons in structural and decorative factors will be used to improve appropriate design.

• Parasites, Hosts and Diseases
• /
• v.57 no.2
• /
• pp.101-115
• /
• 2019

The pathogenesis of cerebral malaria is biologically complex and involves multi-factorial mechanisms such as microvascular congestion, immunopathology by the pro-inflammatory cytokine and endothelial dysfunction. Recent data have suggested that a pleiotropic T-cell immunomodulatory protein (TIP) could effectively mediate inflammatory cytokines of mammalian immune response against acute graft-versus-host disease in animal models. In this study, we identified a conserved homologue of TIP in Plasmodium berghei (PbTIP) as a membrane protein in Plasmodium asexual stage. Compared with PBS control group, the pathology of experimental cerebral malaria (ECM) in rPbTIP intravenous injection (i.v.) group was alleviated by the downregulation of pro-inflammatory responses, and rPbTIP i.v. group elicited an expansion of regulatory T-cell response. Therefore, rPbTIP i.v. group displayed less severe brain pathology and feverish mice in rPbTIP i.v. group died from ECM. This study suggested that PbTIP may be a novel promising target to alleviate the severity of ECM.

• The Korean Journal of Applied Statistics
• /
• v.34 no.5
• /
• pp.671-683
• /
• 2021

Power allocation is a technique that evenly allocates samples for each stratum, although the overall efficiency of the allocation is less than that of optimal allocation, and it is often used as a square root proportional allocation in real survey. Also, considering the non-response that occurs in real survey, a larger sample size is used than that in the theoretical formula. In this study, in determining the sample size for each stratum, we study the new methods of allocating by adding information on the response rate per each stratum to power allocation method. The proposed allocation methods are compare with proportional, optimal, and square root proportional allocation in simulation. In addition, the comparison with the proportional and optimal allocation to which the response rate was added is examined through simulation. As a result, we examine the advantages and disadvantages of the allocation methods.

• Asia-Pacific Journal of Business
• /
• v.11 no.3
• /
• pp.137-151
• /
• 2020

Purpose - The purpose of this study is to investigate whether financial analysts' cash flow forecasts mitigate the accrual anomaly. In addition, we examine whether the more accurate analysts' cash flow forecasts are the greater the decline of the accrual anomaly. Design/methodology/approach - Data used in the empirical tests are extracted through KIS-VALUE and FN-GUIDE, and the sample consists of firms listed on Korea Stock Exchange for 7 years from 2005 to 2011. We test the hypotheses using multiple regression analysis and we also estimate the regressions with the decile ranks of the explanatory variables to minimize the influence of outliers. Findings - We have failed to capture evidence that the provision of financial analysts' cash flow forecasts itself reduces the accrual anomaly. However, we find the accrual anomaly to be less severe when financial analysts provide more accurate cash flow forecasts. The findings are consistent in the regression models with the decile ranks as well as in the robustness tests that controlled the accruals quality. Research implications or Originality - This study contributes to the expansion of related studies in the Korea by providing empirical evidence partially that the financial analysts' cash flow forecasts mitigate the accrual anomaly.

• Journal of Korea Trade
• /
• v.25 no.4
• /
• pp.37-59
• /
• 2021

Purpose - Although models of innovation and exporting dominate recent studies of relations between innovation and access to foreign markets, relations between innovation and foreign direct investment (FDI) are less explored. This is especially true of relations between types of innovation and FDI. We fill that gap in the literature with empirical evidence that clarifies whether firms enter foreign markets through exports or FDI. Design/methodology - In order to assess the role of innovation in firms' international engagement strategies, we develop research hypotheses and present new empirical evidence on firms' choice of entry - exports and FDI - based on firm-level data. Findings - Our empirical results suggest that the impact of product innovation is more significant in transition from being a purely domestic firm to an exporter, while process innovation more significantly affect transition from being an exporter to a multinational enterprise. Our results also support 'self-selection into FDI' rather than 'learning-by-performing FDI' in the relationship between innovation and firms' overseas expansion. Originality/value - Recent literature on the relationship between innovation and firms' participation in foreign markets is dominated by models of innovation and export behavior. However, foreign direct investment by multinational enterprises may also be associated with firms' innovative activities. We first analyze how product and process innovations influence firms' choices to initiate exports or FDI.

• Geophysics and Geophysical Exploration
• /
• v.13 no.4
• /
• pp.315-322
• /
• 2010

The phase-screen and the split-step Fourier migrations, which are implemented in both the frequency-wavenumber and frequency-space domains by using one-way scalar wave equation, allow imaging in laterally heterogeneous media with less computing time and efficiency. The generalized-screen migration employs the series expansion of the exponential, unlike the phase-screen and the split-step Fourier migrations which assume the vertical propagation in frequency-wavenumber domain. In addition, since the generalized-screen migration generalizes the series expansion of the vertical slowness, it can utilize higher-order terms of that series expansion. As a result, the generalized-screen migration has higher accuracy in computing the propagation with wide angles than the phase-screen and split-step Fourier migrations for media with large and rapid lateral velocity variations. In this study, we developed a 2D prestack generalized-screen migration module for imaging a complex subsurface efficiently, which includes various dips and large lateral variations. We compared the generalized-screen propagator with the phase-screen propagator for a constant perturbation model and the SEG/EAGE salt dome model. The generalized-screen propagator was more accurate than the phase-screen propagator in computing the propagation with wide angles. Furthermore, the more the higher-order terms were added for the generalized-screen propagator, the more the accuracy was increased. Finally, we compared the results of the generalizedscreen migration with those of the phase-screen migration for a model which included various dips and large lateral velocity variations and the synthetic data of the SEG/EAGE salt dome model. In the generalized-screen migration section, reflectors were positioned more accurately than in the phase-screen migration section.

• Journal of Internet Computing and Services
• /
• v.24 no.5
• /
• pp.1-7
• /
• 2023

This paper proposes a small cell resource partitioning allocation method to solve interference to machine type communication devices (MTCD) and improve performance in 5G heterogeneous networks (HetNet) where macro base station (MBS) and many small cell base stations (SBS) are overlaid. In the 5G HetNet, since various types of MTCDs generate data traffic, the load on the MBS increases. Therefore, in order to reduce the MBS load, a cell range expansion (CRE) method is applied in which a bias value is added to the received signal strength from the SBS and MTCDs satisfying the condition is connected to the SBS. More MTCDs connecting to the SBS through the CRE will reduce the load on the MBS, but performance of MTCDs will degrade due to interference, so a method to solve this problem is needed. The proposed small cell resource partitioning allocation method allocates resources with less interference from the MBS to mitigate interference of MTCDs newly added in the SBS with CRE, and improve the overall MTCD performace using separating resources according to the performance of existing MTCDs in the SBS. Through simulation results, the proposed small cell resource partitioning allocation method shows performance improvement of 21% and 126% in MTCDs capacity connected to MBS and SBS respectively, compared to the existing resource allocation methods.

• Korean Journal of Remote Sensing
• /
• v.22 no.6
• /
• pp.575-579
• /
• 2006

The land use in suburban area has been changed rapidly due to the urban expansion in Korea during the last few decades. And such land use changes result in various environmental problems such as biodiversity decrease, habitat fragmentation, air pollution and urban heat island. Remote Sensing (RS) and Geographical Information Systems (GIS) can be used for land cover change detection to understand the impact and trend of the land use change. Change detection is the process of identifying differences in the state of an object or phenomenon by observing it at different times and it can provide quantitative and comparative information for the land use/cover change. RS is less expansive than field survey for producing land use maps, and can be accessed quickly and repetitively for large area. Also it can be used for change detection using multi-temporal land use/cover by accumulated data. Therefore, the purpose of this study is to detect and quantitatively evaluate urban land cover change in urban stream watershed area for the last few decades and ultimately to provide the basic data for urban land use planning and management.