• Title/Summary/Keyword: 4-WAY Cassette

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Evaluation of Indoor Thermal Comfort for Ceiling Type System Air-Conditioner with Various Discharge Angles (천장형 시스템 에어컨의 토출방향 변화에 따른 실내 열쾌적성 평가)

  • Lee, Jin-Hyung;Kim, You-Jae;Choi, Weon-Seok;Park, Sung-Kwan;Youn, Baek;Kim, Youn-Jea
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.1180-1185
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    • 2006
  • Modern people spend most of time at indoor space, such as office or classroom. Especially, occupants are exposed to the airtight indoor air quality (IAQ) for a long time, At present, many studies on the air-conditioning systems are more focused on the individual thermal comfort than the thermal efficiency due to increase of the concern of health. There are several factors which are influenced thermal comfort, such as temperature, humidity, convection and air movement, etc. Also, the individual factor, such as age, gender, Physical constitution and habit, should be considered. The 4-way cassette type air conditioner is known to bring out better performance about thermal comfort than the traditional one. This study is performed on the higher ceiling environment than the common buildings or classrooms. Also, this study analyzed on the Indoor thermal comfort by diffusing direction of 4-way cassette air conditioner with various discharge angles, $45^{\circ},\;50^{\circ},\;55^{\circ}$ and $60^{\circ}$. Using a commercial code, FLUENT, three-dimensional transient air thermal flow fields are calculated with appropriate wall boundary conditions and standard $k-{\epsilon}$ turbulence model. Results of velocity and temperature distributions are graphically depicted with various discharge angles.

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Noise Reduction of Turbo Fans for Air-Conditioner Indoor Units (에어컨 실내기 터보팬의 소음 저감)

  • 김진백;최원석;구형모;이재권
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.93-96
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    • 2004
  • A turbo-fan for the 4-way cassette indoor units of air-conditioners has been investigated. The main purpose of this investigation is the reduction of the turbo-fan noise. In order to reduce the noise level, many design parameters of turbo-fans such as blade section, blade thickness, geometry of blade leading edge, blade width, blade angle and bellmouth depth have been studied. With the experimental data of these parameters, a new turbo-fan was made for our system. The noise level of the new system was at least 3 dB(A) lower than that of the current in use.

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A Study on the Comparison of Thermal Comport Performance Indices for Cooling Loads in the Classroom (학교건물에서 냉방부하에 따른 열적 쾌적성 평가지표 비교 연구)

  • Noh, Kwang-Chul;Oh, Myung-Do
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1274-1279
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    • 2004
  • We performed the numerical study on the comparison of thermal comport performance indices for cooling loads in the classroom when the 4-way cassette air-conditioner is mounted on the ceiling. We investigated the velocity and the temperature distribution of the classroom as with respect to the variation of the air diffusion angle of the air-conditioner. Air diffusion performance index and Predicted mean vote were used for analyzing the characteristics of the thermal comport in the classroom and comparing their values each other. From the numerical results, we knew that the thermal comport is largely affected by the air diffusion angle and velocity of the air-conditioner. And we also found out that the qualitative tendency of the distribution between Air diffusion performance index and Predicted mean vote is very similar in all occupied zone.

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Comparison of Thermal Comfort Performance Indices for Cooling Loads in the Lecture Room - An Correlation of PMV Bnd EDT - (강의실에서의 냉방부하에 따른 열쾌적성 평가지표 비교 - PMV와 EDT의 연관성 -)

  • Noh Kwang-Chul;Oh Myung-Do
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.7 s.238
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    • pp.868-877
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    • 2005
  • We performed the experimental and the numerical study on the comparison of thermal comfort performance indices for cooling loads in the lecture room for 4 cases: Fan coil unit(FCU) or 4-way cassette air-conditioner is respectively operated with the ventilation system or without. We measured the velocity, the temperature distribution and predicted mean vote(PMV) value in the lecture room for 4 different air-conditioning methods. Effective draft temperature(EDT) and PMV were investigated to analyze the characteristics of two thermal comfort indices in the lecture room and to compare their values each other. From the results we knew that there is the similarity between PMV values and EDTs when the room is air-conditioned for cooling loads. It turned out that definition of the control temperature is very important when the EDT is calculated. Finally EDT should not be used to predict the accurate thermal comfort in case that the temperature and humidity are suddenly varied and the zone affected by the solar and inner wall radiation.

A Research on the Digital Restoration of the Analog by Removing Hiss Noise (Using X-NOISE Based on Hiss-Noise Reduction) (히스 노이즈제거를 통한 아날로그의 디지털 복원에 대한 연구 - X-NOISE를 활용한 히스 노이즈리덕션을 중심으로 -)

  • Byun, Jung Min;Doo, Ill Chul
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.10 no.4
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    • pp.161-170
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    • 2014
  • Analog cassette tapes are easily changed due to environmental factors. To digitize is the best way to preserve a sound source. The way to digitize is to deal with the original sound to be enhanced to a variety of sources by playing through the audio card after recording. In this process to occur, it's the most important to remove various noise and equalizing sound in a method for preserving. It's studied about how to remove noise by using one of softwares, Cubase 5. 5, to remove hiss noise, which happens changing analog tape into digitalization. A amount of hiss noise is reduced to use X-Noise software of Wave which uses in Cubase 5.0, one of PLUG-IN. The noise is removed changing value of threshold and reduction every 10 times in no change of origin sound. To keep regular condition, the experiment to remove the hiss noise is conducted based on sound meondle, which is one of sound Nonmaegi. The noise is removed easily when the value of threshold is getting high in spite of giving a little value of reduction. However, as it gives a amount of reduction high, the damage rate of the sound source gets high.

A Study on the ventilation Technology for Indoor Air Quality Improvement (실내 공기질 개선을 위한 환기기술에 관한 연구)

  • Chang Tae-Hyun;Cho Hyun-Wook
    • Journal of Advanced Marine Engineering and Technology
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    • v.29 no.5
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    • pp.540-551
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    • 2005
  • In this research, We'll focus on warm environment and ventilation characteristics when utilizing intake ports, exhaust port and 4-way cassettes for removing heat and polluted air. Four way cassettes have been typical air conditioning units for offices since the multi air-conditioner was introduced. The following installation cases will also be discussed: 1) 4-way cassette's operation without intake ports and exhaust port. 2) Effect of the position of intake port and exhaust ports. 3) cooling air flow, temperature. distribution and local supply index according to the air flow rate from 4-way cassettes.

A Study on the Evaluation of Air Change Efficiency of Multi-Air-Conditioner with Ventilation System for Heating Season (환기시스템이 적용된 히트펌프의 난방시 급기효율 평가에 관한 연구)

  • Kwon Yong-Il;Han Hwataik;Kim Kyung-Hwan;Chung Baik-Young;Lee Gam-Gue
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.1
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    • pp.56-61
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    • 2005
  • Indoor air quality becomes of a concern recently in view of human health. This study investigates the air diffusion performance and the air change efficiency of a classroom, when outdoor air is introduced in addition to the heating/cooling operation of a ceiling-mounted heat pump. A CFD analysis has been performed to investigate the effect of the discharge angle of the air jets from the heat pump for both parallel and series types of outdoor air system. It is observed that the series type creates more uniform indoor environment compared to the parallel type in general. It can be concluded the discharge angle should not be larger than 40o for the parallel type, in order not to generate thermal stratification in the room.

The study on the effect of the solar radiation on thermal comfort and ventilation performance in room space (태양일사가 실내공간의 열적 쾌적성과 환기성능에 미치는 영향에 관한 연구)

  • Yeon, Seong Hyeon;Lee, Hyo Joon;Rhee, Gwang Hoon
    • Journal of the Korean Society of Visualization
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    • v.14 no.1
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    • pp.19-26
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    • 2016
  • Modern people spend much time at indoor space. So, People want to make better indoor air condition. But the facade of building is made of glass to be seen urbanely, the effect of solar radiation makes indoor environment worse. This study designs an open space affected by solar radiation with 4-way cassette air-conditioner. Using numerical simulation, this paper investigates thermal comfort and ventilation performance with discharge angles $30^{\circ}$ and $45^{\circ}$. To study thermal comfort, this paper studies distribution of velocity, temperature and effective draft temperature. Also, this paper introduces concept of air age to study ventilation performance. The flow influenced by solar radiation determines thermal comfort and ventilation performance in room space. This study shows that discharge angle of 45 degree has better thermal comfort and ventilation performance than that of 30 degree.

Comparison of the PMV and ADPI according to Adapted Height of Ceiling-type System Air-conditioner in Large space (천정형 정풍량 시스템에어컨의 적용높이에 따른 실내온열환경 특성)

  • Sung, Sang-Chul;Kim, Hyouk-Soon;Chin, Sim-Won;Oh, Myung-Do
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.590-595
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    • 2009
  • PMV and ADPI were numerically investigated in a large space of various ceiling height with air-conditioning systems of two type. The numerical results showed that it is small that the growth of cooling load according to ceiling height rise in a large space without windows. In case of system air-conditioner of duct type embedded in the ceiling, the air mixing effect in indoor is superior to a case installed 4way cassette type in it. For controling thermal comfort at indoor, a system air-conditioner of duct type embedded in the ceiling is little influenced according to ceiling height rise in a large space considered.

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Why A Multimedia Approach to English Education\ulcorner

  • Keem, Sung-uk
    • Proceedings of the KSPS conference
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    • 1997.07a
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    • pp.176-178
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    • 1997
  • To make a long story short I made up my mind to experiment with a multimedia approach to my classroom presentations two years ago because my ways of giving instructions bored the pants off me as well as my students. My favorite ways used to be sometimes referred to as classical or traditional ones, heavily dependent on the three elements: teacher's mouth, books, and chalk. Some call it the 'MBC method'. To top it off, I tried audio-visuals such as tape recorders, cassette players, VTR, pictures, and you name it, that could help improve my teaching method. And yet I have been unhappy about the results by a trial and error approach. I was determined to look for a better way that would ensure my satisfaction in the first place. What really turned me on was a multimedia CD ROM title, ELLIS (English Language Learning Instructional Systems) developed by Dr. Frank Otto. This is an integrated system of learning English based on advanced computer technology. Inspired by the utility and potential of such a multimedia system for regular classroom or lab instructions, I designed a simple but practical multimedia language learning laboratory in 1994 for the first time in Korea(perhaps for the first time in the world). It was high time that the conventional type of language laboratory(audio-passive) at Hahnnam be replaced because of wear and tear. Prior to this development, in 1991, I put a first CALL(Computer Assisted Language Learning) laboratory equipped with 35 personal computers(286), where students were encouraged to practise English typing, word processing and study English grammar, English vocabulary, and English composition. The first multimedia language learning laboratory was composed of 1) a multimedia personal computer(486DX2 then, now 586), 2) VGA multipliers that enable simultaneous viewing of the screen at control of the instructor, 3) an amplifIer, 4) loud speakers, 5)student monitors, 6) student tables to seat three students(a monitor for two students is more realistic, though), 7) student chairs, 8) an instructor table, and 9) cables. It was augmented later with an Internet hookup. The beauty of this type of multimedia language learning laboratory is the economy of furnishing and maintaining it. There is no need of darkening the facilities, which is a must when an LCD/beam projector is preferred in the laboratory. It is headset free, which proved to make students exasperated when worn more than- twenty minutes. In the previous semester I taught three different subjects: Freshman English Lab, English Phonetics, and Listening Comprehension Intermediate. I used CD ROM titles like ELLIS, Master Pronunciation, English Tripple Play Plus, English Arcade, Living Books, Q-Steps, English Discoveries, Compton's Encyclopedia. On the other hand, I managed to put all teaching materials into PowerPoint, where letters, photo, graphic, animation, audio, and video files are orderly stored in terms of slides. It takes time for me to prepare my teaching materials via PowerPoint, but it is a wonderful tool for the sake of presentations. And it is worth trying as long as I can entertain my students in such a way. Once everything is put into the computer, I feel relaxed and a bit excited watching my students enjoy my presentations. It appears to be great fun for students because they have never experienced this type of instruction. This is how I freed myself from having to manipulate a cassette tape player, VTR, and write on the board. The student monitors in front of them seem to help them concentrate on what they see, combined with what they hear. All I have to do is to simply click a mouse to give presentations and explanations, when necessary. I use a remote mouse, which prevents me from sitting at the instructor table. Instead, I can walk around in the room and enjoy freer interactions with students. Using this instrument, I can also have my students participate in the presentation. In particular, I invite my students to manipulate the computer using the remote mouse from the student's seat not from the instructor's seat. Every student appears to be fascinated with my multimedia approach to English teaching because of its unique nature as a new teaching tool as we face the 21st century. They all agree that the multimedia way is an interesting and fascinating way of learning to satisfy their needs. Above all, it helps lighten their drudgery in the classroom. They feel other subjects taught by other teachers should be treated in the same fashion. A multimedia approach to education is impossible without the advent of hi-tech computers, of which multi functions are integrated into a unified system, i.e., a personal computer. If you have computer-phobia, make quick friends with it; the sooner, the better. It can be a wonderful assistant to you. It is the Internet that I pay close attention to in conjunction with the multimedia approach to English education. Via e-mail system, I encourage my students to write to me in English. I encourage them to enjoy chatting with people all over the world. I also encourage them to visit the sites where they offer study courses in English conversation, vocabulary, idiomatic expressions, reading, and writing. I help them search any subject they want to via World Wide Web. Some day in the near future it will be the hub of learning for everybody. It will eventually free students from books, teachers, libraries, classrooms, and boredom. I will keep exploring better ways to give satisfying instructions to my students who deserve my entertainment.

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