• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.116-119
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• 2007

The application of light weight materials, such as aluminum alloy, has been limited due of their poor formability. Especially, aluminum alloy tube has limited expansion capability at most 15% at room temperature. New manufacturing process, called hot air forming, is introduced to apply aluminum tube to the automotive suspension components which have complex shape and require high expansion ratio about 40%. The process is carried out at the elevated temperature above $500^{\circ}C$, so numerous material properties and process parameters related to the high temperature should be investigated and determined to get a sound product. In this study, the effect of thermal properties and forming parameters such as the temperature of tool, axial feeding and gas pressure are analyzed by using explicit finite element method.

• Journal of the Korean Wood Science and Technology
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• 제36권2호
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• pp.9-20
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• 2008

Anatomical comparison of 3 North American species with commercial name of redcedar was executed to provide taxonomic information for prevention of confusion and establishment of sound business transaction in the wood market. Eastern redcedar (Juniperus virginiana) and southern redcedar (Juniperus silicicola) could not be separated on the basis of microstructure and ultrastructure of wood. Western redcedar (Thuja plicata), however, appeared to be obviously separated from eastern and southern redcedar in a number of microscopic and ultramicroscopic features. Useful features for separating these two groups were intercellular spaces in transverse surface, latewood width, radial intertracheid pitting, warty layer and pits with torus extensions in tracheids, ray composition, nodular end walls in ray parenchyma cells, and cross-field pitting.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1609-1611
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• 1994

In ECR and helicon reactors for plasma processing, a high density plasma is generated in a source region which is connected to a diffusion region where the processing takes place. Large density and potential gradients can develop at the orifice of the source which drive ion currents into the diffusion region. The average ion velocity may become the order of the sound velocity. Measurements of the ion saturation current to a Langmuir probe are used as a standard method of determining the plasma density in laboratory discharges. However, the analysis becomes difficult in a steaming plasma. We have used the HAMLET plasma simulator to simulate the ion flow to a large langmuir probe in an ECR plasma. The collection surface was aligned with the Held upstream, normal to the field, and downstream. ion trajectories through the electric and magnetic fields were calculated including ion-neutral collisions. We examines the ratio of ion current density to plasma density as a function of magnetic field and pressure.

• 한국정보과학회논문지:소프트웨어및응용
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• 제28권1호
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• pp.73-89
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• 2001

본 연구에서는 일반화된 let-다형성(let-polymorphic) 타입 유추 알고리즘을 제시하고, 이로부터 얻어지는 모든 예 알고리즘들은 Hindley/Milner 타입 체계를 안전하고 완전하게 (sound and complete) 구현하고 있음을 증명하며, 일반화된 알고리즘의 두 예 알고리즘들간에 어느 한쪽이 항상 오류를 더 신속히 감지하게 되는 조건을 제시한다. 일반화된 알고리즘으로부터 이론적으로 검증된 두 타입 유추 알고리즘, 즉, 상향성 표준 타입 유추 알고리즘 W와 하향성 알고리즘 M 뿐만 아니라 두 알고리즘의 혼성 알고리즘(hybrid algorithm)을 만들 수 있다. 만들어진 예 알고리즘들의 안전성, 완전성, 상대적인 신속한 오류 감지 성질들은 본 논문의 증명에 의해 자동적으로 유추된다. 본 논문에서 제시되는 알고리즘으로부터 만들어 낼 수 있는 예 알고르즘에는 SML/NJ와 Objective Caml 컴파일러에서 채택한 알고리즘을 포함하고 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.37-45
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• 2003

The diesel engines was invented a little more than one hundred years ago and has ever since been developed for better fuel economy, increased power and smaller size. Thanks to its fuel economy, the diesel engine is today the dominating prime mover in many applications, such as smaller power plants, commercial ships, trains, trucks, buses and all kinds of mobile construction machinery. As engine for passenger cars, the diesel engine is steadily increasing its share of the market. However, its versatility and, consequently, large prevalence have led to environmental demands to its exhaust emissions, noise and vibration. This paper deals with the noise aspects of diesel engine designs of the so-called low speed two-stroke type installed in most large ships.

• 전자통신동향분석
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• 제32권6호
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• pp.1-7
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• 2017

A metamaterial is a material engineered to have a property that does not exist in nature. A designable material property can be achieved by tailoring its structure, and thus a metamaterial is a novel ICT material and component technology that can break through the limitations of conventional technologies. Among the metamaterials available, a perfect metamaterial absorber is a technology that can nearly absorb light, sound waves, thermal waves, and electromagnetic waves with a simple structure, and has been of significant interest in energy, display, sensor, stealth, and military applications, with wavelengths from visible light to microwaves. In this article, we introduce a brief description of metamaterial absorber technology, the critical issues for its application, as well as ETRI's developed metamaterial absorber technology and its prospects for future use.

• 천문학회지
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• 제33권2호
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• pp.123-126
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• 2000

We have developed a near real-time flare alerting system which (1) downloads the latest GOES-l0 1-8 ${\AA}$ X-ray flux 1-min data by an automated ftp program and shell scripts, (2) produces a beep sound in a simple IDL widget program when the flux is larger than a critical value, and (3) makes it possible to do a wireless alerting by a set of portable transceivers. Thanks to the system, we have made successful Ha flare observations by the Solar Flare Telescope in Bohyunsan Optical Astronomy Observatory. This system is expected to be helpful for ground-based flare observers.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.833-836
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• 2006

The purpose of study is to develope for lightweight concrete panel which have high quality with insulation performance of sound. The use of lightweight concrete products has been increased at a recently high structures. Also, the gathering of nature aggregate is limited, so that lack of fine aggregate is appearing. Statistical analysis is practiced on the properties of EPS concrete according to the variation of mix design. As a result saturated density is affected by amount of Bottom ash.Also compressive strength is affected by W/B ratio at the early age and amount of Bottom ash at the latter age.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.201-205
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• 2005

도로조명은 야간에 운전자에게 안락함과 안전한 운행을 도울 수 있도록 설치가 이루어져야한다. 최근 늘어나는 자가용에 의해서 주택가나 공공장소에 발생하는 소음을 감소시키기 위하여 도로 위 필요지점들에 방음벽이 설치되어지고 있다. 그러나 현재 이에 적합한 형태의 조명기구가 개발되지 못한 상황이며, 이에 따라서 방음벽에 설치가 가능한 도로조명기구의 반사판을 개발하였다. 개발된 반사판은 도로에 대해 연직방향으로 위치한 방음벽에 그대로 설치되어질 수 있는 형태이며, 도로조명기준에 맞추어 전반 균제도 0.4와 차선 축 균제도 0.7 이상을 만족할 수 있도록 설계되었고, 단위 면적당 소비전력 $1.18[W/m^2]$의 효과를 얻었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3253-3255
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• 1999

출생시 국내에서 영아 사망률은 약 1%에 이르고 태아의 질병발생과 사망은 계속적으로 일어나고 있으므로 저가의 태아감시기술의 개발이 절실하다. 이를 위하여 본 연구는 임산부의 복부로부터 태아의 움직임과 심음을 검출하는 증폭기의 개발을 목표로 한다. 검출된 신호는 듣거나 녹음할 수 있으며. A/D 변환할 경우 PC에서 태아의 심음을 분석할 수 있게 한다. 개발된 증폭기를 이용하여 잡음에 노출된 일반 대학병원 환경에서 30명의 임산부를 대상으로 임상실험을 수행한 결과, 저잡음 특성을 나타내고. 빠른 경우 22주에서도 태아의 심음을 검출할 수 있었고. 심음의 주기검출이 가능하였다.