• Proceedings of the Korean Information Science Society Conference
• /
• 1999.10c
• /
• pp.563-565
• /
• 1999

인터넷 서비스의 급속한 확산과 기술 발전으로 인하여 대량의 정보를 고속으로 전송하기 위해 고속의 링크 기술을 이용하고, ATM 인터넷 기간망을 수용하고 다양한 서비스 품질을 제공하는 등 다양한 차세대 인터넷 기술의 등장과 함께 네트워크 구조에 많은 변화가 이루어지고 있다. 또한, 다양한 인터넷 응용의 등장과 함께 인터넷 이용자의 네트워크 트래픽이 급속도로 증가하고 있다. 이에 따라 인터넷의 다양한 트래픽을 특성지울 수 있는 플로우 개념을 이용하여 이용자 네트워크 사용 패턴 및 망 관리 방안등을 제시할 수 있다. 이러한 데이터를 분석하여 인터넷의 성능 및 특성을 평가하는 것은 단기적, 중기적, 장기적인 네트워크 설계관점에서 매우 중요한 기초연구이다.

• Journal of ILASS-Korea
• /
• v.9 no.2
• /
• pp.18-23
• /
• 2004

An experimental studies of conventional gasoline fuel pump were carried out to obtain fundamental data fur liquid phase LPG injection(LPLi) system. A regenerative type and a roller-vane type of pumps were investigated in various operational condition. The experiments were performed to obtain flow rate of LPG fuel as a function of pressure differences and temperatures. The regenerative pump had too low flow rate at some experimental conditions to use this pump system for LPLi fuel supply system. On the other hand, the roller-vane type pump can be applied to the system only if its check valve is modified. Cavitation might occur in this system which can result in system noise, flow rate variation, and pump durability problem. To solve these problems the system is needed to increase $NPSH_{re}$(required net positive suction head).

• Nuclear Engineering and Technology
• /
• v.53 no.9
• /
• pp.2839-2846
• /
• 2021

In this study, experiments of downward-facing flow boiling were conducted to investigate material effects on CHF. Experiments were conducted using aluminum, copper, and carbon steel. It was found that different materials had different CHFs. Aluminum has the biggest CHF while copper has the lowest CHF for each mass flux. After experiment, surface wettability increased and surface became rougher, which was probably due to the oxidation process during nucleate boiling. The CHF difference is likely to be related to the surface wettability, roughness and thermal effusivity, which influences the bubble behavior and in turn affects CHF. Further studies are needed to determine which factor is dominant.

• Journal of Ecology and Environment
• /
• v.30 no.2
• /
• pp.109-119
• /
• 2007

The effect of water flow on the growth of Gafrarium tumidum was studied in the field using open cages constructed with stainless steel net and perspex in which holes were drilled. Cages with different flows (25, 50 and 75% of the control) were made by varying the area of perspex being drilled. Reduction in flow rate was directly proportional to the undrilled area, and the mean flow rate of the different treatment groups varied from 3.12 cm/s for the 25% exposure to 12.48 cm/s for the control cages. At the end of the 3-month experiment, no significant differences in sediment characteristics were found among the treatments. Growth in shell length, shell weight and tissue dry weight was, however, positively correlated with flow rate. Percentage increases ranged from $3.0{\sim}8.3%$ for shell length, $9.9{\sim}23.1%$ for shell weight and $17.2{\sim}53.3%$ for tissue dry weight. Condition index of the clam was not significantly different among the treatments. Seston depletion effect could reduce growth in G. tumidum only when water flow was reduced to 25% of the control. G. tumidum also exhibited different responses in shell and tissue growth at low flow rates, in which shell growth continued to decrease as flow rate decreased whereas tissue growth was relatively independent of low flows at 25 and 50% of the control. It was suggested that when seston flux was reduced at slow flows, it would be a better strategy for G. tumidum to channel energy for gonad development instead of shell growth during the reproductive stage.

• The Journal of Information Systems
• /
• v.9 no.1
• /
• pp.109-128
• /
• 2000

This paper examined the significance of Intellectual Capital. In recent years the number of companies whose value lies largely with their intellectual capital has increased dramatically. Dr. Margaret Blair of the Brookings Institute reported a significant shift in the makeup of company assets. In 1978, her study showed that 80 pecent of the firms＇value was associated with its tangible assets, with 20 pecent associated with its intangible assets. By 1998, only 30 pecent of the value of the firms studied was attributable to tangible assets while 70 pecent was associated with the value of their intangibles. This paper used the result of her study. This paper tested the correlation of enterprise value and intellectual capital, cash flow, net income and net assets. The results showed that the correlation of enterprise value and intellectual capital was most significant.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2012.11a
• /
• pp.42-45
• /
• 2012

A network processor (NP) is an application-specific instruction-set processor for fast and efficient packet processing. There are many issues in compiler's code generation and optimization due to NP's hardware constraints and special hardware support. In this paper, we describe in detail how to resolve the issues. Our compiler was developed on LLVM 3.0 and the NP target was our in-house network processor which consists of 32 64-bit RISC processors and supports multi-context with special hardware structures. Our compiler incurs only 9.36% code size overhead over hand-written code while satisfying QoS, and the generated code was tested on a real packet processing hardware, called S20 for code verification and performance evaluation.

• Nuclear Engineering and Technology
• /
• v.52 no.9
• /
• pp.1955-1962
• /
• 2020

In a sudden shutdown of primary pump or coolant loss accident in a marine nuclear power plant, the primary flow decreases rapidly in a transition process from forced circulation (FC) to natural circulation (NC), and the lower flow enters the steam generator (SG) causing reverse flow in the U-tube. This can significantly compromise the safety of nuclear power plants. Based on the marine natural circulation steam generator (NCSG), an experimental loop is constructed to study the characteristics of reverse flow under middle-temperature and middle-pressure conditions. The transition from FC to NC is simulated experimentally, and the characteristics of SG reverse flow are studied. On this basis, the experimental loop is numerically modeled using RELAP5/MOD3.3 code for system analysis, and the accuracy of the model is verified according to the experimental data. The influence of the flow variation rate on the reverse flow phenomenon and flow distribution is investigated. The experimental and numerical results show that in comparison with the case of adjusting the mass flow discontinuously, the number of reverse flow tubes increases significantly during the transition from FC to NC, and the reverse flow has a more severe impact on the operating characteristics of the SG. With the increase of flow variation rate, the reverse flow is less likely to occur. The mass flow in the reverse flow U-tubes increases at first and then decreases. When the system is approximately stable, the reverse flow is slightly lower than obverse flow in the same U-tube, while the flow in the obverse flow U-tube increases.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.25 no.5
• /
• pp.9-14
• /
• 2002

A capital investment problem is essentially one of determining whether the anticipated cash inflows from a proposed project are sufficiently attractive to invest funds in the project. The net present value(NPV) criterion and internal rate of return(IRR) criterion are widely used as means of making investment decisions. A positive NPV means the equivalent worth of the inflows is greater than the equivalent worth of outflows, so, the project makes profit. Business people are familiar with rates of return because they all borrow money to finance ventures, even if the money they borrow is their own. Thus they are apt to use the IRR in preference to the NPV. The IRR can be defined as the discount rate that causes the net present value of a cash flow to equal zero. Why the project are accepted if the project's IRR is greater than the investor's minimum attractive rate of return\ulcorner Against the NPV, the definition cannot distinctly explain the concept of the IRR as decision criterion. We present a new definition of the IRR as the ratio of profit on the invested capital.

• Nuclear Engineering and Technology
• /
• v.51 no.4
• /
• pp.977-986
• /
• 2019

In the thermal-hydraulic system codes, such as MARS and RELAP5/MOD3, the Savannah River Laboratory (SRL) model has been adopted as a subcooled boiling model. It, however, has been shown that the SRL model cannot take into account appropriately the effects of inlet liquid velocity and hydraulic diameter on axial void fraction development. To overcome the problems, Ha et al. (2018) proposed a modified SRL model, which is applicable to low-pressure and low-Pe conditions (P < 9.83 bar and $Pe{\leq}70,000$) only. In this work, the authors extended the modified SRL model by proposing a new net vapor generation (NVG) model and a wall evaporation model so that the new subcooled boiling model can cover a wide range of thermal-hydraulic conditions with pressures ranging from 1.1 to 69 bar, heat fluxes of $97-1186kW/m^2$, Pe of 3600 to 329,000, and hydraulic diameters of 5-25.5 mm. The new model was implemented in the MARS code and has been assessed using various subcooled boiling experimental data. The results of the new model showed better agreements with measured void fraction data, especially at low-pressure conditions.

• The Korean Journal of Health Service Management
• /
• v.11 no.1
• /
• pp.1-9
• /
• 2017

Objectives : Cash Flows from operating activities is the most important part of the cash flow statement and it serves as an important financing source. Accordingly, the purpose of this study is to examine the influence of the contents of cash flows from operating activities on the changes in borrowings. Methods : In this study financial data from 2011 to 2014 were used to analyz 36 general hospitals and 85 hospitals according to the index displaying variation against the previous year. Results : For general hospitals, borrowings in cash flow from financing activities increased as net income decreased; while depreciation etc increased in cash flow from operating activities. For hospitals, borrowings in cash flow from financing activities increased as the gain on disposition of tangible assets in cash flow from operating activities decreased. Conclusions : General hospitals need to control the management of borrowings and depreciation at the level of funding management; whereas hospitals need to manage of future cash forecasts for stability of operational funds.