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- 저자 : 박경섭 ( Kyeong-seob Park ) (검색결과 4 건)
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아공정 Al-Si 합금에서 Si 함량과 냉각속도에 따른 제이차수지상간격의 변화
박경섭,김희수,Park, Kyeong-Seob,Kim, Hee-Soo 한국주조공학회 2017 한국주조공학회지 Vol.37 No.4
In this study, we investigated the effect of the Si content on the secondary dendrite arm spacing (SDAS) of hypoeutectic Al-Si binary alloys in the range of 4~10 wt% Si. Cooling curves were measured during the solidification of the alloy cast in a step-wise mold. We compared two kinds of solidification time: the first is the total solidification time for both dendritic and eutectic growth, and the second is the solidification time for only dendritic growth. The proportional constant in the relationship between SDAS and cooling rate was estimated, as this constant represents the stability of the cast microstructure. The proportional constant decreased with the Si contents from 4 wt% to 8 wt%, and it remains relatively uniform with up to 10 wt% of Si.
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환형주조품의 용탕충진에 미치는 탕도연장부와 주입구 형상의 영향
박경섭 ( Kyeong Seob Park ),강신욱 ( Shin Wook Kang ),김희수 ( Hee Soo Kim ) 한국주조공학회 2015 한국주조공학회지 Vol.35 No.2
In this study, potential defects of ring-type cast products during the mold-filling stage of the casting process were investigated using computer simulation. The main focus was on the effects of runner extension and ingates. During the mold filling the molten metal flowed from the bottom to the top of the mold in two curved paths along the ring-type cavity. The fluid fronts in the two paths did not show the identical velocity during the mold filling stage. This difference in the filling speeds may cause defects such as voids and local contractions. The present model contained virtual fluid detectors at various positions inside the mold. When the molten metal passed those points, the volume of fluid jumped up from zero to one. The moments were measured to compare the speeds of the fluid fronts. We attempted various combinations of runner extensions and ingates to stabilize the flow and then to optimize the casting mold design.
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다이캐스팅 ADC12 합금의 열처리 전후의 기계적 특성변화
강신욱 ( Shin-wook Kang ),박경섭 ( Kyeong-seob Park ),오은호 ( Eun-ho Oh ),심정일 ( Jung-il Shim ),김희수 ( Hee-soo Kim ) 한국주조공학회 2016 한국주조공학회지 Vol.36 No.3
We investigated the effect of heat treatment on an ADC12 alloy produced using diecasting. The heat treatment used in this study was a typical T6 process: a solid solution treatment followed by an artificial aging treatment. As-cast specimens were solid-solution-treated at 500oC and 530oC for 1-16 hr, and aged at 160oC and 180oC for 1-8 hr. Microstructural changes in the alloy during the heat treatment were observed. Changes in mechanical properties of the alloy were measured using a micro Vickers hardness tester. Finally, we determined the optimal heat treatment conditions for the diecast ADC12 alloy.
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이승원,박경섭 울산대학교 1997 공학연구논문집 Vol.28 No.1
적당한 성능의 광섬유 자이로스코프는 자동차 주행용의 회전율 측정 센서로 사용할 수 있다. 본 논문에서 구성한 광섬유 자이로스코프 시스템은 개회로 방식의 신호 처리를 하며, 단일 모드 광섬유와 방향성 결합기를 이용하여 시스템을 광섬유 일체식으로 구성하였다. 광원으로는 비편광 광원인 He-Ne 레이저를 사용하였다. 자동차 주행용으로 사용할 수 있도록 간단한 구성과 저가격이 되도록 하였다. 본 논문에서는 modified J₁…J₄ 방법을 응용한 신호 처리 방식을 사용하였다. 간섭계 출력을 고속 푸리에 변환(fast Fourier transform : FFT)하여 4 개의 연속 고조파를 구한 다음, modified J₁…J₄를 적용하여 변조도(modulation index)를 구한다. 이 방법은 광원의 파장변동이나 편광 상태의 변화 등에 상관없이 계측할 수 있다. 여기서 구한 변조도를 이용하여 Bessel 함수 ??를 계산한 결과와, 두 고조파의 비로 간단하게 회전율을 구할 수 있었다. Fiber-optic gyroscope of modest performance can be used as angular rate sensor for vechile navigation on land. A practical design is used an open-loop configuration with an all-fiber optical system together with single-mode fiber and directional coupler. We use the unpolarized light source, He-Ne laser as light source, and design simple construction for low cost. In this paper, we used the modified J₁…J₄ method which apply the signal processing technique. Measurements were made of the amplitudes of four harmonics in the electrical spectrum of the output of an interferometer using fast Fourier transform(FFT), and modified J₁…J₄ was used to determine the amplitude of the modulation index. This method allowed us independents of the wavelength fluctuation of the wavelength fluctuation of source and state of polarization changes in measurement. We can simply get the rotation rate with two harmonics ratio, Bessel function, ?? and the modulation depth.
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