• Journal of Advanced Navigation Technology
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• v.1 no.1
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• pp.47-58
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• 1997

In this paper, the modified aviation TDMA protocol that can improve the aeronautical communication spectrum utilization is studied to satisfy the increasing air traffic demands. Currently European states proposed the scheme reducing the channel spacing from current 25 kHz to 8.33 kHz and U. S. FAA proposed the system using TDMA technique that divides access into four parallel circuits. The modified aviation TDMA protocol can complement the defects of these current systems. In modified aviation TDMA protocol, message channel that is used between aircraft and ground station is divided into uplink channel and downlink channel. After receiving the acknowledgement of the reservation request, aircraft sends messages at the allocated slots. Numerical analysis and simulation results show that the modified aviation TDMA scheme has high channel efficiency in the aviation environment.

• Progress in Medical Physics
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• v.14 no.4
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• pp.249-258
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• 2003

A few years ago, a proposal was made to change the dosimetry from the air kerma-based reference dosimetry to the absorbed dose-based reference dosimetry for all radiotherapy beams of ionizing radiation to improve the accuracy of dosimetry. Here, we present a dosimetry study in which the two most widespread absorbed dose­based protocols (IAEA TRS­398 and AAPM TG­51) were compared with an air kerma­based protocol (IAEA TRS-277) by measuring the absorbed dose in the same reference depth. Measurements were performed in three clinical electron beam energies using a PTW 30002 cylindrical chamber, and Markus and Roos plane­parallel chambers. $^{60}$ Co calibration factors were obtained from the KFDA. The absorbed dose differences between the air kerma­based and absorbed dose­based protocols were within 2.0% for all chambers in all beams. The results thus show that the obtained absolute dose values will be not significantly altered by changing from the air kerma­based dosimetry to the absorbed dose­based dosimetry. It was also shown that absorbed dose values between the absorbed dose­based protocols agreed by deviations of less than 0.5% for a cylindrical chamber and less than 0.7% for plane­parallel chambers using cross­calibration factors. Although the use of a cylindrical chamber and plane­parallel chambers resulted in a difference of less than 2% for all situations investigated here, to reduce errors, the plane­parallel chambers are recommended for electron energies in which the use of cylindrical chamber is not permitted in each protocol.

• Electronics and Telecommunications Trends
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• v.10 no.4 s.38
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• pp.113-127
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• 1995

본 고에서는 이동국과 기지국간 신호방식에 적용되는 PCS 무선 접속 프로토콜에 대하여 기술한다. 기본적인 내용구성은 Proposed W-CDMA PCS 표준화를 기본으로 하여 무선 인터페이스 프로토콜 기능 및 구조 그리고 기본호절차와 메시지 포맷 및 내용으로 이루어져 있다. 또한 오류 조건 처리에 대하여도 기술한다.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1744-1759
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• 2007

This study intended to identify the problems of the railroad which are raised as one of the 21C next-generation but to define the direction for the absence of the national policy and examine the competitiveness of railway transportation which is a Green Network with low environmental destruction and high energy efficiency as the continuable means of transportation for the 21st century with superiority to energy crisis caused by high oil price, conclusion of the Kyoto Protocol for worsened air pollution, and reduced cost of traffic jam.

• Electronics and Telecommunications Trends
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• v.11 no.3 s.41
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• pp.45-55
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• 1996

본 고에서는 이동국과 기지국간 신호방식에 적용되는 PCS 이동성 관리 프로토콜에 대하여 기술하였다. 기술의 내용으로는 Proposed W-CDMA PCS 표준화를 기본으로 하여 이동성 관리 프로토콜 기능 및 구조 그리고 기본호 절차, 메시지 포맷 및 내용으로 이루어져 있으며, 오류처리에 대해서도 기술하였다.

• Phonetics and Speech Sciences
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• v.7 no.4
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• pp.93-99
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• 2015

In case of PAS test, the air is sometimes leaked although the mask is tightly attached to the face, which is not reliable on the measured values. Therefore, this study aimed to assist the clinical practice suggesting the test method of PAS without air leakage. In the healthy subjects with 12 males and 12 females over 19 years old, three types of tests were performed on the voicing efficiency among the protocol of PAS Model 6600. They are; first, to attach the mask tightly to the face holding the handle of PAS with the subject's two hands (Method 1); second, to attach the mask tightly to the face holding the handle of PAS with the subject's one hand and pushing the body of PAS strongly with the other hand (Method 2); and third, to attach the mask tightly to the face pushing the upper part of the mask by the tester when the subject attached the mask to his or her face holding the handle of PAS with two hands (Method 3). Upon the study analyses, the mean negative pressure, the mean phonogram, subglottic air pressure, and voicing efficiency were shown to be statistically significantly different during PAS test in males depending on the methods. (p<.05) In case of females, only the target airflow rate showed significant difference depending on the methods during PAS test. (p<.001) In conclusion, Method 2 enhanced the noise level and strength while Method 1 was likely to leak the air more compared to the other two methods in males. In case of females, Method 1 showed significant leakage of the air flow. Not to allow the air flow leakage without affecting the outcome of PAS test, it will be the most useful for the tester to push the mask to the subject's face tightly (Method 3).

• KIEAE Journal
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• v.1 no.2
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• pp.21-28
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• 2001

Naturally-ocurring short-lived decay products of radon gas in indoor air are the dominant source of ionizing radiation exposure to the general public. It is written in BEIR VI Report(l999l the radon progeny were identified as the second cause of lung cancer next to cigarette or 10 % to 14 %(15,400 to 21,800 persons p.a.) of all lung cancer deaths in USA. Indoor radon concentrations in houses typically result from radon gaining access to houses mainly from the underlying soil. In the States, they have "Indoor Radon Abatement Act" which was converted from "Toxic Substance Control Act" in 1988 to establish the national long-term goal that indoor air should be as free of radon as the ambient air outside of buildings. To review and study techniques for controlling radon, two test cells were constructed for a series of tests and are under measuring indoor and soil gas (underneath of floor slab)radon concentrations according to EPA's measurement protocol. In this paper, important theoretical studies are previewed and the following paper will explain the test results and confirm the theories reviewed to find out suitable coefficients. On the basis of test analysis, it will be described and evaluated various techniques that can be used to mitigate elevated indoor concentration of radon including the control of radon and its decay products.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.345-352
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• 2010

In this study, external condensation heat transfer coefficients(HTCs) of R134a and R1234yf are measured on a plain, low fin, and Turbo-C tubes at the saturated vapor temperature of $39^{\circ}C$ with the wall subcooling of $3{\sim}8^{\circ}C$. R1234yf is a new alternative refrigerant of low greenhouse warming potential for replacing R134a which is one of the greenhouse gases controlled by Kyoto protocol and is used extensively in mobile air-conditioners. Test results show that the external condensation HTCs of R1234yf are very similar to those of R134a for all three surfaces tested. For the application of condensation heat transfer correlations to the design of condensers charged with R1234yf, thorough property measurements are needed for R1234yf in the near future.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.434-439
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• 2005

In order to prevent the global warming, Korea has had a ratification to the Kyoto Protocol which is specified the air pollution level should be lower the condition of the year 1990 until the year 2012, in hence the traffic system produced mostly the air pollution has been faced to big change. According to the reinforcement of higher level for environmental condition, alternative way to the conventional traffic system is required, so that is fuel cell technology of commercialized R&D program used by hydrogen fuel, and further for the optimized high energy efficiency it has been considered the advanced development of traffic system used the conventional railroad system. But it is moreover expected the huge amount of initial investment, so at the current, next new traffic system is needed. This study is for the improvement of urban traffic system in domestic which should be seriously changed for environmental friendly through the reduction of air pollution by fuel gases of vehicle and human convenience to be easily approached. In hence it is proposed the development of superior high efficiency-'Fuel-cell Rubber-tired Tram' system manufactured by the composite car-body.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.4 s.23
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• pp.58-67
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• 2005

To overcome limitations of test scope, schedule and cost, M&S(Modeling & Simulation) technique has been applied for T&E(Test and Evaluation) of the state-of-art weapon systems. This paper proposes an air defense simulation software framework to reduce both redundancy an[1 programming errors in system simulator. The proposed framework consists of a 'model' and a 'middleware' The 'middleware' is a reliable communication service layer that supports not only HLA(High Level Architecture) which is an international standard in M&S but also TCP/IP, UDP and etc. The main role of 'model' is to schedule and to run the real-time distributed simulation. The proposed framework has been applied to M-SAM(Middle range Surface to Air Missile) system simulator. The proposed framework's scheduling and communication performance results are satisfactory and were measured by hardwired NTP(Network Timer Protocol) time-stamp with GPS(Global Positioning System) timer for better precision.