• Journal of information and communication convergence engineering
• /
• 제6권3호
• /
• pp.327-330
• /
• 2008

It is required that a server which communicates with various client simultaneously should have an efficient data transfer model. In Windows$^{(R)}$ environment, the server was generally developed based on IOCP model. Developing the IOCP model, the server generally has one data transfer buffer per client. If the server divides a larger data than the transfer buffer into several fragments, there used to be a problem in sending it to a client, because there is a conflict in a data transfer buffer. That is, CPU requests one data-fragment transfer, then it will request the next data-fragment transfer successively before completing the previous request, owing to the property of overlapped IO model. In this paper, we proposed the transfer buffer sharing technique to solve the conflicting problem. The experimental result shows that the performance of data transfer was enhanced by 39% maximally.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제12권1호
• /
• pp.37-49
• /
• 2004

Four different data reduction methods for the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two heat and mass transfer models and two fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the reduced heat transfer coefficients revealed that the single potential heat and mass transfer model yielded the humidity-independent heat transfer coefficients. Two fin efficiency models-enthalpy model and humidity model-yielded approximately the same fin efficiencies, and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

• 한국항공우주학회지
• /
• 제47권2호
• /
• pp.161-168
• /
• 2019

본 논문에서는 소형 무인기 데이터 링크 시스템에 적용이 가능한 전송률 가변 비대칭 TDD(Time Division Duplex) 방식에 대해 다루었다. 긴 복호 시간이 필요한 터보 복호기를 비대칭 TDD 방식에 적용하기 위하여 이중 버퍼 제어기 구조의 터보 복호기를 제안하였다. 제안 방법은 전송률 가변과 동일 송수신 시간에 최대의 데이터 전송이 가능하다. 제안 방식을 적용한 데이터 링크 시스템을 제작하여 성능을 확인하였다. 측정 결과, 대칭 TDD 방식에 비해 전송률은 최대 약 1.8배 증가하였다. PER(Packet Error Rate) 성능은 동일하며, 전송률 가변이 가능함을 확인하였다.

• 대한기계학회논문집
• /
• 제17권10호
• /
• pp.2624-2633
• /
• 1993

Mass transfer experiment by naphthalene sublimation method has great advantages in measurement of local transfer coefficients in the region of a three dimensional flow or for a model of complex geometry, which is considered to be very difficult with conventional heat transfer measurements. Mass transfer data obtained by naphthalene sublimation technique are converted to the heat transfer data through heat/mass transfer analogy. This analogy is valid for a simple or laminar flow, but new insight is needed when applying to a turbulent flow or complex flow such as separation, reattachment and recirculation, The purpose of this research is to investigate how geometries and flow conditions incorporate heat/mass transfer analogy. Mass transfer experiments are performed using naphthalene sublimation technique for a flat plate, a circular cylinder, and rectangular cylinders. And mass transfer data are compared with earlier heat transfer measurements for the same geometries. Usefulness of analogy relation between heat and mass transfer is examined with these results.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2005년도 추계종합학술대회
• /
• pp.1225-1228
• /
• 2005

This paper compares the differences between Java virtual machine and x86 processor in data transfer viewpoint. Memory models of JVM and x86 are analyzed and the data transfer paths are identified. As all operations must be performed to the values on operand stack, a great many data transfer operation is unavoidable in JVM. We also lists the number of data transfer operations necessary for executing some typical high-level language statements including assignment, arithmetic, conditional, and iterative statements.

• Journal of Mechanical Science and Technology
• /
• 제15권12호
• /
• pp.1711-1727
• /
• 2001

Heat transfer coefficient were measured and new correlations were developed for two-phase heat transfer in a horizontal pipe for different patterns. Flow patterns were observed in a transparent circular pipe (2.54 cm I. D. and L/D=96) using an air/water mixture. Visual identification of the flow patterns was supplemented with photographic data and the results were plotted on the flow regime map proposed by Taitel and Dukler and agreed quite well with each other. A two-phase heat transfer experimental setup was built for this study and a total of 150 two-phase heat transfer data with different flow patterns were obtained under a uniform wall heat flux boundary condition. For these data, the superficial Reynolds number ranged from 640 to 35,500 for the liquid and from 540 to 21,200 for the gas. Our previously developed robust two-phase heat transfer correlation for a vertical pipe with modified constants predicted the horizontal pipe air-water heat transfer experimental data with good accuracy. Overall the proposed correlations predicted the data with a mean deviation of 1.0% and an rms deviation of 12%.

• 설비공학논문집
• /
• 제15권1호
• /
• pp.73-85
• /
• 2003

Four different methods of reducing the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two different heat and mass transfer models and two different fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the data with the reduction methods revealed that the single potential heat and mass transfer model yielded the humidity independent heat transfer coefficients. Two different fin efficiency models - enthalpy model and humidity model - yielded approximately the same fin efficiencies and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

• 대한토목학회논문집
• /
• 제38권5호
• /
• pp.693-701
• /
• 2018

수도권 도시철도의 환승통행은 '노선간환승'과 '역사환승'으로 구분된다. 역사환승은 1) 교통카드 Tag-In 단말기 운영노선과 초승열차 운영노선이 다른 경우와 2) 최종 하차열차 운영노선과 교통카드 Tag-Out 단말기 운영노선이 다른 경우에 발생한다. 기존연구에서 주로 교통카드자료를 이용한 환승량 추정은 '노선간 환승량'을 의미하며 '역사환승량'은 제외되어 환승통로를 이용하는 보행에 대한 과소추정의 원인이 되었다. 본 연구는 수도권 대중교통카드자료를 이용해서 역사환승량을 추정하는 방안을 제시한다. 이를 위해 승객의 경로선택모형에 역사환승량 산정에 적합하도록 변형된 Big-Node 기반 네트워크 구축기법과 자료구조 방법론을 제시한다. 1일 약 800만 건의 수도권 도시철도 이용카드자료를 대상으로 사례분석을 시행한다.

• 한국수정란이식학회:학술대회논문집
• /
• 한국수정란이식학회 2000년도 추계학술대회 및 정기총회
• /
• pp.74-83
• /
• 2000

• 설비공학논문집
• /
• 제14권3호
• /
• pp.231-239
• /
• 2002

Experiments on the single phase cooling heat transfer and pressure drop with microfin tubes were performed using water as a test fluid. Experimental data were obtained in the range of Reynolds number 3000 ~40000 and Prandtl number 4-6. The data of microfin tubes presented the characteristics of rough surface tube in pressure drop and heat transfer Experimental data were compared with the heat transfer and friction factor correlations of smooth tubes. Heat transfer enhancements of microfin tubes were lower than pressure drop penalty factors. The helix angle is more significant parameter in both of the pressure drop and heat transfer than the relative roughness. The correlations of Nusselt number and friction factor were suggested for the tested microfin tubes. Maximum deviations between correlations and experimental data were within $\pm15$% for Nusselt number and $\pm10$% for friction factor.