• Title/Summary/Keyword: Large chamber

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The Basic Study of Internal Temperature Variation in a 3D Printer(FDM-type) Chamber (3D 프린터의 챔버 내부온도 변화에 대한 연구)

  • Shin, Geun-Sik;Kweon, Hyun-ku;Kang, Yong-Goo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.3
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    • pp.33-40
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    • 2019
  • FDM 3D printers have become widespread, and investment in the 3D printer industry is increasing. Therefore, many 3D printers are released and the functions of products are emphasized. However, to lower unit prices, open-type 3D printers are sold in kit form, and their performance is very low. If the 3D printer has many heat sources and is sealed, there is the possibility that the main accessories (the main board, power supply, and motor) will be damaged by trapped heat. At the same time, if the ambient temperature is low due to the properties of the material, the output quality deteriorates. In this study, we analyzed the temperature rise of the main accessories and the quality of the output by the heat bed when a chamber was added to an open-type 3D printer. We also compared the quality of the output due to the air flow with the temperature rise of the main accessories. Moreover, we found the optimal value. As a result of the quality analysis, it was finally confirmed that the case with the chamber at $95^{\circ}C$ was the best for the printing condition. In addition, in the absence of the chamber, the bending of the specimen was found to be large, and in the case of the chamber, the degree of bending was slightly decreased by 0.05 mm.

The Structual Restoration on Gyeongju-Style Piled Stone-Type Wooden Chamber Tombs (경주식 적석목곽묘의 구조복원 재고)

  • Gweon, Yong Dae
    • Korean Journal of Heritage: History & Science
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    • v.42 no.3
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    • pp.66-87
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    • 2009
  • The definition of the structure of wooden chamber tomb(piled stone-type) is as follows. It is a tomb with wooden chamber, and stones were piled on top of the wooden chamber, and then a wooden structure was placed on top of the piled stones, and more stones were piled on top of the wooden structure, and sealed with clay. Of course this definition can vary according to periods, the buried, etc. Gyeongju-style piled stone type wooden chamber tombs have some distinguished characteristics compared to general definition of piled stone type wooden chamber tombs. Outside the wooden chamber, either stone embankments or filled-in stones were layed out, and pilet-in stones are positioned right above the wooden chamber, and almost every class used this type, and finally, it is exclusively found in Gyeongju area. First generations of this Gyeongju-style piled stone type wooden chamber tombs appeared in first half of 5th century. These tombs inherited characteristics like ground plan, wooden chamber, double chamber(inner chamber and outer chamber), piled stones, burial of the living with the dead, piled stones, from precedent wooden chamber tombs. However these tombs have explicit new characteristics which are not found in the precedent wooden chamber tombs such as stone embankments, wooden pillars, piled stones(above ground level), soil tumuluses. stone embankments and wooden pillars are exclusively found on great piled stone type above-ground level wooden chamber tombs such as the Hwangnamdaechong(皇南大塚). Stone embankments, wooden pillars, piled stones(above ground level) are all elements of building process of soil tumuluses. stone embankments support outer wall of above-ground level wooden chambers and disperse the weight of tumuluses. Wooden pillars functioned as auxiliary supports with wooden structures to prevent the collapse of stone embankments. Piled stones are consists of stones of regular size, placed on the wooden structure. And after the piled stones were sealed with clay, tumulus was built with soil. Piled stones are unique characteristics which reflects the environment of Gyeongju area. Piled stone type wooden chamber tombs are located on the vast and plain river basin of Hyeongsan river(兄山江). Which makes vast source of sands and pebbles. Therefore, tumulus of these tombs contains large amount of sands and are prone to collapse if soil tumulus was built directly on the wooden structure. Consequently, to maintain external shape of the tumulus and to prevent collapse of inner structure, piled stones and clay-sealing was made. In this way, they can prevent total collapse of the tombs even if the tumulus was washed away. The soil tumulus is a characteristic which emerges when a nation or political entity reaches certain growing stage. It can be said that after birth of a nation, growing stage follows and social structure will change, and a newly emerged ruling class starts building new tombs, instead of precedent wooden chamber tombs. In this process, soil tumulus was built and the size and structure of the tombs differ according to the ruling class. Ground plan, stone embankments, number of the persons buried alive with the dead, quantity and quality of artifacts reflect social status of the ruling class. In conclusion, Gyeongju-style piled stone type wooden chamber tombs emerged with different characteristics from the precedent wooden chamber tombs when Shilla reached growing stage.

Study on Effective Point of Measurement for Parallel Plate Type ionization Chamber with Different Spacing (평행평판형 이온함의 두 전극간의 간격 변화에 따른 유효측정점에 관한 연구)

  • 신교철;윤형근
    • Progress in Medical Physics
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    • v.13 no.2
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    • pp.55-61
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    • 2002
  • In this work, EPM (effective point of measurement) of parallel plate ionization chamber with three different spacing were investigated. If the plate separation is less than 2 mm one generally assumes that the effective point of measurement is just behind the front window of the parallel plate ionization chamber. For chamber with relatively large separation, such as the ones used for very accurate exposure measurements, this assumption breaks down and the EPM depends on plate separation and thickness of the front window. For parallel plate chambers, conventional theoretical analyses suggest that the EPM is the inner front wall and that it shifts towards the geometric centre of the chamber as the plate separation increases. The PP-IC (parallel plate ionization chamber) is fabricated using acrylic plate for the chamber medium and printed circuit board for electrical configuration. The various sizes of the sensitive volumes designed so far are 0.9, 1.9, and 3.1 cc. The gap between two electrodes ranges from 3, 6, and 10mm. Also the charge-to-voltage converter is designed to collect the electrons produced in the ionization chamber cavity. As the result of our experiment, the EPM shift was within 0.6 mm in photon beams and 0.4 mm to 2.5 mm in electron beams for the plate separation of 6 mm and 10 mm. EPM shifts towards the geometric center of the chamber as the plate separation increases.

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Antenna Measurement on Cylindrical Surface in Fresnel Region Using Direct Far-Field Measurement System

  • Oh, Soon-Soo;Kim, Joung-Myoun;Yun, Jae-Hoon
    • ETRI Journal
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    • v.29 no.2
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    • pp.135-142
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    • 2007
  • The small anechoic chambers built by many small-/medium-sized companies and universities present difficulties in testing electrically large antennas because the chamber size cannot satisfy the far-field criterion of large antennas. In this paper, a method for Fresnel-region measurement on a cylindrical surface with variation of the measurement height is proposed and verified by both calculations and experiments. We implement the proposed method using a direct far-field measurement system by adding a few supporting structures. The results show good accuracy.

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Optimization Design of Large Gas Oven Systems (대형 가스오븐 시스템의 최적 설계)

  • Kim, Dohyun;Yu, Byeonghun;Kum, Sungmin;Lee, ChangEon
    • 한국연소학회:학술대회논문집
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    • 2015.12a
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    • pp.205-207
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    • 2015
  • In this study, we examined through experimental study of the combustion conditions in order to optimize the 20,000kcal/hr class combustor being used in the commercial large gas oven. Through a consideration of the shape and the heat transfer area of the heat exchanger that is suitable for supplying heat quantity is designed and manufactured two heat exchangers were examined cooking chamber temperature change of the oven by the convection fan control method through advanced research.

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Interior Settings of a Chamber and a Temporary Place of Enshrinement at Yeonghuijeon and Features of the Five Peak Screens for the Hall (영희전 감실 및 이안소의 공간 구성과 오봉산병풍의 특징)

  • SON Myenghee
    • Korean Journal of Heritage: History & Science
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    • v.56 no.2
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    • pp.100-121
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    • 2023
  • This paper examines the interior settings of a chamber and of a temporary place of enshrinement at Yeonghuijeon (永禧殿, Hall of Eternal Happiness), the representative official portrait hall in which portraits of early and late Joseon kings were enshrined. Also, it discusses the features of the Five Peak screens used therein. The physical environment of a chamber at Yeonghuijeon mainly consisted of a four-panel folding screen with a painting of Five Peaks and a large wooden platform, which was adorned with dragon and lion patterns and attached to lotus-leaf column balustrades. The Five Peak screen was installed on a large platform in the shape of ⊓, spreading across the second and third panels on the back and folding out on the first and fourth panels on the right and left sides. When a portrait was enshrined in a temporary place, a simpler and smaller platform with railings was used. A four-panel folding screen of the Five Peak painting was installed in the same way as in a chamber, but was unfolded around a smaller platform behind it. A royal portrait was displayed in each chamber, whereas a case in which a portrait was rolled up was put on the smaller platform in a temporary place. The Five Peak screens for a chamber and a temporary place were all large four-panel folding screens with two wide panels in the middle and two narrow panels on each side, and only strips of silk were mounted on the four edges of the screens without additional wide lower-side mountings. While screens for the chamber used patterned silk for mounting and white paper for backing on screen frames, screens for the temporary place used plain silk and recycled failed test papers for mounting and backing, respectively. By examining records in the literature on the Five Peak screens for Yeonghuijeon, this paper highlights two Five Peak screens, both of which lost their provenance from the hall. The structures of the two screens reflected the way they were to be installed at the hall. Furthermore, this paper assumes that a Five Peak screen, which had been unfolded on the throne in the main hall of Changdeokgung Palace after the 1960s, was produced in 1858 for the purpose of temporarily enshrining King Sunjo's portrait due to the fact that failed test papers of the 1840s were laid taut over the frame.

Combustion Characteristics of Landfill Gas in Constant Volume Combustion Chamber for Large Displacement Volume Engine (I) - Fundamental Characteristics - (대형기관 모사 정적연소실에서 매립지 가스의 연소특성에 대한 연구 (I) - 기초 특성 -)

  • Ohm, Inyong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.8
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    • pp.733-741
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    • 2013
  • This is the first paper on the combustion characteristics of landfill gas in a constant volume combustion chamber for a large displacement volume commercial engine, and it discusses the fundamental characteristics of fuel from the viewpoint of thermochemistry and thermodynamics and compares these results with experimental ones. The results show that the final pressures obtained from theoretical analysis vary under the same heating value owing to the change in the constant volume specific heat owing to the difference in the burned gas composition according to the fuel gas compositions; furthermore, the stoichiometric ratios and trends of analytical and experimental pressures coincide very well, although some minor differences are observed between the two. The root cause of the difference is the heat transfer, which changes the specific heat and lowers the temperature considerably, in the real combustion process. In addition, the large chamber volume and ignition position promote the heat transfer to the wall. Finally, the fuel conversion efficiency increases as the methane mol fraction decreases, and it is maximum when the stoichiometric ratio ranges from 0.8 to 0.9. These increases due to the composition and stoichiometric ratio could sufficiently compensate the decrease due to the specific heat ratio drop, LFG might be more advantageous than pure methane in a real engine.

A Study on Control System of Multi Layer Sputtering Equipment (다층 박막 스퍼터링 장비의 제어시스템에 관한 연구)

  • Lee, Sun-Jong;Yoo, Heung-Ryol;Son, Yung-Deug
    • Journal of IKEEE
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    • v.22 no.2
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    • pp.302-308
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    • 2018
  • Multi-Layer Sputtering is aim to develop desired thickness thin film multi-layer with different materials. The multi-layer thin film deposition process occupies a relatively large portion in the process time, because the main reason is that it takes much time to move the substrate to be deposited and to make the chamber into a high vacuum state compared to the process time. Most of semiconductor and display industries sputter a single substance in one chamber and move boards through multi-continuous robots to another chamber to sputter other materials. This will inevitably require multiple chambers, vacuum pumps, and multi-contamination robots within the process facility. To solve these problems, this paper proposes a control system for multi-layer thin film sputtering devices that deposit different materials within a single vacuum chamber and is applied in TFT process. The manufacture and experiment of the control system proved its validity.