• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.153-153
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• 2014

건식 진공펌프(dry vacuum pump)는 기계적 저진공펌프 중 펌프 내부의 기체 배기통로에 오일을 전혀 사용하지 않는 펌프의 통칭으로써, 대개 비접촉형으로 여러 형태의 회전자가 고속으로 회전하면서 흡기구로부터 들어온 기체를 압축해 배기를 한다. 비접촉형에는 루츠(roots)형, 클로(claw)형, 스크류(screw)형, 스크롤(scroll)형 등이 있다. 그 중 스크류형 펌프는 큰 배기속도를 갖는 펌프의 설계에 유리하고 높은 운용온도가 가능하여 다수공정에 쉽게 적용할 수 있는 장점이 있다. 그러나 1단 펌프 구성을 갖게 됨에 따라 루츠형 대비 높은 소비전력 특성을 보이는 약점을 가지고 있다. 본 논문에서는 건식 진공펌프 중의 하나인 스크류형 진공펌프에 대하여, 기본적인 1단 펌프 구성에 스크류 리드(lead)의 변화를 주어 기존의 똑같은 리드의 스크류 진공펌프에 대한 소비전력 및 배기구 온도 등 스크류 형상에 대한 성능평가 연구를 진행 하고자 한다.

• Journal of the Korean Solar Energy Society
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• v.34 no.3
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• pp.42-48
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• 2014

An experimental study was performed estimating COP(Coefficient of Performance) of air-conditioning cycle with inverter scroll compressor. All experiments were done for various compressor speeds from 1000~4000 rpm and used the inverter controller called CANDy to change the compressor rpm. The air-conditioning cycle components in the apparatus were used as same with components of YF hybrid car. To estimate the COP, this study measured the temperature and pressure at inlets and outlets of compressor, condenser, and evaporator. And also measured the compressor input power using Powermeter. Through the experiments, the maximum error to estimate COP was shown about ${\pm}6.09%$ at 3500rpm. This study revealed that the condenser temperature and pressure were increased and the evaporator temperature and pressure were decreased with the increased compressor speed. And also, the COP was decreased with increased compressor speed. Those results can be used the basic and fundamental data to design the air-conditioning cycle with inverter scroll compressor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.919-926
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• 2013

Experiments were conducted to determine the operating characteristics of a small-scale ORC (organic Rankine cycle) system for various low-temperature heat sources. A small-scale ORC power generation system adopting R-245fa as a working fluid was designed and manufactured. Hot water was used as the heat source, and the temperature was controlled using 110-kW electric resistance heaters that provided temperatures of up to $150^{\circ}C$. An open-drive oil-free scroll expander directly connected to a synchronous generator was installed in the ORC unit. Experiments were conducted by varying the rotational speed of the expander under the same heat source temperature conditions. The factors that influence the performance of the small-scale ORC system were analyzed and discussed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.107-112
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• 1996

본 논문에서는 문자나 그래픽 요소에 대한 실시간 다중 디지털 효과를 구현한 프리즘젬 장비를 소개한다. 프리즘 젬은 문자를 포함한 여러 그래픽 요소에 대하여 각기 다른 디지털 효과를 편집하여 실시간으로 동시에 효과를 수행할 수 있어서 방송 화면에 다양한 표시 효과를 제공한다. 프리즘젬은 그래픽 보도와 특별히 제작된 효과용 보드를 장착한 PC형 장비로 소형이며 경제적이다. 프리즘젬은 다양한 문자와 그래픽을 편집할 수 있고, 이들에 대한 위치 변환, 크기 변환, 회전, 기울임, 구부림, 퍼뜨림, 클리핑, 스크롤, 블링킹 등의 효과와 함께 곡선이나 나선형과 같은 다양한 경로 이동 효과를 줄 수 있다. 본 논문에서는 프레즘젬 장비와 하드웨어 구성, 실시간 다중 디지털 효과를 위한 효과 보드의 동작 원리, 실시간 처리 성능, 복합적인 모양 변형 효과를 구현하기 위한 효과 변환 함수의 모델링 방법, 경로 이동 효과를 포함한 효과 애니메이션 방법, 운용 소프트웨어 기능 등에 대한 내용을 기술한다.

• Tribology and Lubricants
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• v.23 no.3
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• pp.83-88
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• 2007

This paper presents measurement processes of rotational accuracy and comparison of theoretical values in the main bearing of scroll compressor. The main bearing is a type of oil journal bearing, but it has an axial or helical groove. The generalized coordinate system method, which can handle this groove, is applied to calculate the pressure profile in the journal bearing. The orbits of journal shaft are calculated corresponding to the compressed gas forces and bearing reaction forces. Then, the orbits are measured using three-point method. The results are compared to that from analyses.

• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.59-64
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• 2010

A design method of Sirocco fan is developed for constructing 3-D impeller and scroll geometries, and for predicting both the aerodynamic performance and the noise characteristics of the designed fan. The aerodynamic blading design of fan is conducted by blade angle, camber line determinations and airfoil thickness distribution, and then the scroll geometry of fan is designed by using logarithmic spiral. The aerodynamic performance of designed fan is predicted by the meanline analysis with flow blockage, slip and pressure loss correlations. Based on the predicted performance data, fan noise is predicted by two models for cutoff frequency and broadband noise sources. The present predictions for the performance and the noise level of actual fans are well agreed with measurement results.

• Cartoon and Animation Studies
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• s.46
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• pp.85-106
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• 2017

With the media's shift into the digital era in the 2000s, comic book publishers attempted a transition into the new medium by establishing a distribution structure using internet networks. But that effort shied from escaping the parallel-page reading structure of traditional comics. On the other hand, webtoons are showing divers changes by redesigning the structure of traditional sequential art media; they tend to separate and allot spaces according to the vertical scroll reading method of the internet browser and include animations, sound effects and background music. This trend is also in accordance with the preferences of modern readers. Modern society has complicated social structures with the development of various media; the public is therefore exposed to different stimuli and shows characteristics of differentiated perceptions. In other words, webtoons display more relevant and entertaining characteristics by inserting sounds and using moving texts and characters in specific frames, while traditional comics require an appreciation of withdrawal and immersion like other published media. Motions in webtoons are partially applied for dramatic tension or to create an effective expression of action. For example, hand-drawn animation is adopted to express motions by dividing motion images into many layers. Sounds are also utilized, such as background music with episode-related lyrics, melodies, ambient sounds and motion-related sound effects. In addition, webtoons provide readers with new amusement by giving tactile stimuli via the vibration of a smart phone. As stated above, the vertical direction, time-based nature of animation motions and tactile stimuli used in webtoons are differentiated from published comics. However, webtoons' utilization of innovative techniques hasn't yet reached its full potential. In addition to the fact that the software used for webtoon effects is operationally complex, this is a transitional phenomenon since there is still a lack of technical understanding of animation and sound application amongst the general public. For example, a sound might be programmed to play when a specific frame scrolls into view on the monitor, but the frame may be scrolled faster or slower than the author intended; in this case, sound can end before or after a reader sees the whole image. The motion of each frame is also programmed to start in a similar fashion. Therefore, a reader's scroll speed is related to the motion's speed. For this reason, motions might miss the intended timing and be unnatural because they are played out of context. Also, finished sound effects can disturb the concentration of readers. These problems come from a shortage of continuity; to solve these, naturally activated consecutive sounds or animations, like the simple rotation of joints when a character moves, is required.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1030-1035
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• 2012

In this research, we analysed design and CFD analysis of an inflow radial turbine for OTEC with an output power of 8kW using an working fluid of ammonia. The inflow radial turbine consists of scroll casing, vain nozzle with 18 blade numbers and rotor blade with 13 blade numbers. Mass flow rate, and inlet temperature are 0.5kg/s and $25^{\circ}C$ respectively, and variable rotational speeds were applied between 12,000 and 36,000 with 3,000 rpm intervals. As the results according to the rotational speeds, the designed speed is 24,000 rpm where maximum efficiency exists. The maximum efficiency and output power are 88.66% and 8.52kW, respectively. Through this study, we expect that the analysed results will be used as the design material for the composition of the turbine optimal design parameters corresponding to the target output power under various working material conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.4
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• pp.495-507
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• 1998

The transient characteristics of a 4.0㎾ inverter driven heat pump was investigated by theoretical and experimental studies. The heat pump used in this study consists of a high side scroll compressor and $\Phi$7 compact heat exchangers with two capillary tubes. A series of tests was peformed to examine the transient characteristics of heat pump in heating and cooling mode when the operating speed was varied from 30Hz to 102Hz. One of the major issues that has not been addressed so far is transient characteristics during speed modulation. A cycle simulation model has been developed to predict the cycle performance under frequency rise-up conditions, and the results of theoretical study were compared with the results of experimental study. The theoretical model was driven from mass conservation and energy conservation equations to predict the operation points of refrigerant cycle and the performances at various operating speeds. For transient conditions, the simulated results are in good agreement with the experimental results within 10%. The transient cycle migration of the liquid state refrigerant causes a significant dynamic change in system. Thus, the migration of refrigerant is the most important factor whenever An experimental analysis is performed or A simulation model is developed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2171-2180
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• 1991

An analysis model for off-design performance of radial inflow turbines with or without variable area guide vane is developed, where two important factors in loss models, total pressure ratio between variable area guide vane exit and scroll casing inlet and rotor loss coefficient are determined without experimental data. The analysis results show that the predicted trends with or without variable area guide vane are consistent with the experimental observations. The comparison of present method with the well-known NASA off-design performance analysis program shows that the mass flow rate and static efficiency by present analysis are in good agreement with those by the NASA program. Therefore, this method can be used to predict off-design performance of radial inflow turbines with validity of the loss models used by present analysis.