• 헤리티지:역사와 과학
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• 제39권
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• pp.281-314
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• 2006

Several explanations exist about the usage of disk-shaped bronze implements in the ancient society. Some argue that they were used as mirrors, others suggest percussion instruments, and still others bronze ornaments. Differences between disk-shaped bronze implements and mirrors with multiple knobs are that the former have no visible design, only one handle, and a sharp curvature unlike the latter with smooth curvature. The question is whether disk-shaped bronze implements excavated from Korean peninsula have any light reflecting function. To answer this question, I carefully studied the concave surfaces of disk-shaped bronze implements excavated from Goejeong-dong, Tongso-ri and Hapsong-ri sites. The main findings are as follows: (1) The concave sides of the disk-shaped bronze implements excavated from Goejeong-dong and Tongso-ri sites were highly polished, and they were as reflective as bronze mirrors. (2) The concave side of the disk-shaped bronze implement from Hapsong-ri site was unpolished, and it was different from bronze mirrors. (3) As for the convex sides of the disk-shaped bronze implements, they did not appear to have been polished with care. Considering the above findings, the disk-shaped bronze implements excavated from Goejeong-dong and Tongso-ri sites belong to the stage where they could act as both mirrors and instruments. On the contrary, the disk-shaped bronze implement from Hapsong-ri site can belong to the stage where it lost the function of being a mirror as the result of maintaining only its function as an instrument. Even though disk-shaped implements had two functions, it can be considered that the light reflecting function expanded the role of a mirror with multiple knobs and the sound function helped the engraved round bronze implement to be converted into an eight-armed bronze rattle. Since it has been reported that shamans used bronze mirrors as percussion instruments in their performances in Korean peninsula and Siberia, I propose a reconsideration of the usage of mirrors in the ancient East Asia. Although the essential function of a mirror is to reflect light, other possible usages involving important functions need to be further investigated.

• 한국도로학회논문집
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• 제18권4호
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• pp.37-45
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• 2016

PURPOSES : The objective of this study was to develop an impact resonance (IR) test procedure for thin disk-shaped specimens in order to determine the ${\mid}E^*{\mid}$ and phase angle values of various asphalt mixtures. METHODS : An IR test procedure was developed for evaluating thin disk-shaped specimens, in order to determine the dynamic modulus (${\mid}E^*{\mid}$) of various asphalt mixtures. The IR test method that was developed to determine the elastic modulus values of Portland cement concrete was evaluated, which method uses axisymmetric flexural vibration proposed by Leming et al. (1996). The IR tests were performed on three different mixtures of New York with varying nominal maximum aggregate sizes (NY9.5, NY19, and NY25) at six different temperatures ($10-60^{\circ}C$). The ${\mid}E^*{\mid}$ values obtained from the IR tests were compared with those determined by the commonly used AASHTO T342-11 test. RESULTS AND CONCLUSIONS : The IR test method was employed to determine the ${\mid}E^*{\mid}$ values of thin-disk-shaped specimens of various asphalt mixtures. It was found that the IR test method when used with thin disk-like specimens is a simple, practical, and cheap tool for determining the ${\mid}E^*{\mid}$ values of field cores. Further, it was found the ${\mid}E^*{\mid}$ values obtained from the IR tests using thin disk-like specimens were almost similar to those obtained using the AASHTO T342-11 test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.266-271
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• 1996

Optimal design of disk shaped piezoelectric actuator and sensor mounted on the plate structure is studied for the control of noise radiated fro the structure. The sensor signal is returned to the actuator through negative gain. Finite element modelling is used for the plate structure and the disk shaped piezoelectric sensor and actuator. The objective function is the total radiated sound power and the design variables are the locations and sizes of the piezoelectric actuator and sensor. The optimal is performed at the resonance and the off resonance frequency and the results show good noise reduction.

• 한국건축시공학회지
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• 제23권1호
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• pp.11-22
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• 2023

본 연구에서는 디스크형 공시체를 활용하여 콘크리트의 깊이별 열화도를 평가하기 위한 방법을 개발하고자 하였다. 이를 위해 원통형 콘크리트 시편의 동탄성계수는 양단자유공진주기법을, 디스크형 콘크리트 시편의 동탄성계수는 임펄스 기법과 충격공진기법을 활용하여 측정하였고, 이를 비교 분석하였다. 실험결과, 임펄스 기법 및 충격공진기법 모두 동일한 지름일 경우 두께가 두꺼워지면 디스크 시편의 동탄성계수는 원주형 공시체의 동탄성계수에 가깝게 측정되었으며, 그 값의 변동성 은 줄어들었다. 또한 같은 (두께)/(반지름) 비율일 경우 지름이 증가하면 디스크 시편의 동탄성계수 측정값의 변동성은 감소하였고, 이러한 경향은 충격공진기법을 이용한 측정에서 더욱 분명하게 나타났다. 디스크의 동탄성계수 측정 시 지름 100mm, 두께25mm의 시편에 대해 충격공진기법을 이용하는 것이 오차율을 줄일 수 있는 방법으로 확인되었다.

• Journal of the Korean Wood Science and Technology
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• 제21권2호
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• pp.39-48
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• 1993

End-matched disks of 7.7cm thickness were part-time dried in vacuum press dryer to investigate the drying characteristics by using drying schedules and end treatments. The ginkgo disks could be dried faster with severer end checks and ring failures by C schedule than by S schedule. There were no significant differences in drying rates and amounts of end checks, ring failures and V-shaped checks occurred between ginkgo disks end-taped with Korean traditional paper (KTP) and those untreated. The drying time of walnut disks was slightly reduced by end-taping with KTP. And the length of end checks and V-shaped checks and the frequency of defected disk were decreased more effectively than those untreated. The tangential strains and tangential drying stresses near bark sides of ginkgo and walnut disk untreated were developed in the early stage of drying and incresed slightly curvi-linearly above fiber saturation point (fsp) and more curvi-linearly below fsp. The influence of end-taping with KTP on the drying rate for impermeable walnut disk was stronger than that for permeable ginkgo disk.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.157-160
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• 2001

본 논문에서 5.8GHz의 주파수 대역에서 사용할 수 있는 향상된 커플링 구조와 크기를 줄인 dual-mode microstrip bandpass filter를 설계하였다. 여기서 meander loop resonator를 쓰는 이유는 크기가 작고 방사 손실이 적으며 패턴이 간단하기 때문이다. 또한 이와 비슷한 특성을 갖는 ring, square patch, disk등은 불연속 성분을 가짐으로써 이중모드의 구현이 가능하다. 향상된 형태의 dual-mode microstrip bandpass filter의 변형된 T-shaped meander loop resonator를 소형으로 발전되고. 높은 선택도를 가지는 구조이다. 이 형태의 filter에서 150MHz의 bandwidth을 가지고 5.8GHz주파수를 가지는 구조로 설계하였다.

• 패션비즈니스
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• 제15권6호
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• pp.23-39
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• 2011

Scythian Earrings in the Black Sea region had completely degenerated, stifled by motifs and shapes of Greek origin, retaining its representational realism and its full emotional vitality. The purpose of this study is to review and research the symbolic meaning and classifying the types of the Scythian Earrings style through the tombs bequests. The Scythian Earrings were divided into the styles according to the shape, Earring with Ends Shaped like animal's Heads, Boat-Shaped Earrings, Bird-Shaped Pendants earrings, Earrings with a Disc and a Pendant, Earrings Shaped like the Figures, Earring with the drop Pendant, Spiral Earrings. Earrings based on the boat shape enjoyed a long popularity among the Scythians. As that form became elaborated and combined with the disk-pendent, it reflected native rather than Asian or Hellenic tastes. Although Scythian earrings were produced based on the shapes of Greece earrings, they recreated these as Scythian unique style. In particular, the animal motive and the decoration have various changes. The exquisite earrings attest to the elegant taste and splendid wealth of the upper classes.

• Tribology and Lubricants
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• 제2권1호
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• pp.61-68
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• 1986

Effects of the ram-pressure on the THD-performance of pivoted pad thrust bearings are investigated experimentally. A sector-shaped tilting pad thrust bearing and a rotating disk are used. Temperature distribution on the disk surface as well as on the pad surface, distribution of the pressure generated within the fluid film, and the film thickness are measured continuously in the circumferential direction after thermal equilibrium is established. The ram-pressure is proportional to the mean pressure of oil film and to the rotational speed of the disk and affects the maximum pressure and the pressure distribution. The temperature rise on the mating surface of the disc and the pad, contacting with the oil film, is proportional to to the bearing load and the disk speed. The ram-pressure and the temperature rise on the disk surface are dominant factors that affect the THD-performance of pivoted pad thrust bearings.

• 한국정밀공학회지
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• 제22권2호
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• pp.60-69
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• 2005

In electrostatic suspension system of thin plates like a silicon wafer or an aluminum disk for hard disk applications, the lateral restoring force exerted on a suspended object plays an important role since the lateral motion of the suspended object, owing to the inherently stable restoring forces, can be passively stabilized without any active control of it. This paper reports about the measurement apparatus of the lateral restoring force originating from a relative translation of the suspended object with respect to the electrodes-for-suspension. An approximate calculation of the lateral force in disk-shaped objects, the structure of the measurement apparatus, a measurement method, stabilization condition and the guideline in designing the measurement apparatus are described. Experimental results obtained by using a 3.5-inch aluminum disk as a suspended object are presented as well in order to assess the magnitude of lateral force and stiffness, and also verify the usefulness of the measurement apparatus.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.137-142
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• 2003

In automotive brake systems, the frictional heat generated can cause high temperature at the interface of rotor and pad which may deteriorate the material properties of the sliding parts and can result in brake fade. Conventionally, a pie-shaped 3-dimentional model is adopted to calculate temperature of ventilated disk using finite element method. To overcome the difficulties in preparing 3D finite element model and reduce the computational time required, the ventilated rotor is to be analyzed, in this study, as an axisymmetric finite element model in which, taking into considerations the effects of cooling passages, a homogenization technique is used to obtain the equivalent thermal properties and boundary conditions for the elements placed at the vent holes. Numerical tests show the proposed procedure can be successfully applied in practice, replacing 3-dimensional thermal analysis of ventilated disk.