• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.11
• /
• pp.101-106
• /
• 2001

In this work, an effort is made to investigate the behavior of a chip, from its initial flow to its final breaking stage. The expression for chip flow in grooved tools is verified analytically using FEM. Cutting parameters like velocity and depth of cut have a profound influence on chip flow behavior. Chip curling increases and, for a given tool geometry, effectiveness of the groove increases with increasing depth of cut. The feasibility of tool design using FEM simulations is also demonstrated. Optimization of tool geometry results in better chip control.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.891-894
• /
• 2001

In this work, an effort is made to investigate the behavior of a chip, from its initial flow to its final breaking stage. The expression for chip flow in grooved tools is verified analytically using FEM. Cutting parameters like velocity and depth of cut have a profound influence on chip flow behavior. Chip curling increases and, for a given tool geometry, effectiveness of the groove increases with increasing depth of cut. The feasibility of tool design using FEM simulations is also demonstrated. Optimization of tool geometry results in better chip control.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.6
• /
• pp.133-140
• /
• 1999

In this study, a monitoring method to detect chip disposal state in drilling system based on neural network was proposed and its performance was evaluated. If chip flow is bad during drilling, not only the static component but also the fluctuation of dynamic component of drilling. Drilling torque is indirectly measured by sensing spindle motor power through a AC spindle motor drive system. Spindle motor power being measured drilling, four quantities such as variance/mean, mean absolute deviation, gradient, event count were calculated as feature vectors and then presented to the neural network to make a decision on chip disposal state. The selected features are sensitive to the change of chip disposal state but comparatively insensitive to the change of drilling condition. The 3 layerd neural network with error back propagation algorithm has been used. Experimental results show that the proposed monitoring system can successfully recognize the chip disposal state over a wide range of drilling condition even though it is trained under a certain drilling condition.

• Journal of Climate Change Research
• /
• v.3 no.3
• /
• pp.211-224
• /
• 2012

Technology for energy recovery from waste can reduce the greenhouse gas emissions. So recently, there are several companies using RDF, RPF, WCF instead of using only coal fuel and it's part of the fuel on the increase. In this study, we developed Wood chip fuel $CO_2$ emission factor through fuel analysis. It's moisture content is 23%, received net calorific value is 2,845 kcal/kg, and received basis carbon is 34%. The result of emission factor is $105ton\;CO_2/TJ$, it's 5.9% lower than 2006 IPCC guideline default factor $112ton\;CO_2/TJ$. The gross GHG(Greenhouse gases) emissions of plant A is $178,767ton\;CO_2 eq./yr$, and Net GHG emissions is $40,359ton\;CO_2 eq./yr$. Therefore, the reduction of GHG emissions is $138,408ton\;CO_2/yr$ through using WCF, and I accounts for 77% of all GHG emissions.

• Journal of Korean Society of Forest Science
• /
• v.111 no.1
• /
• pp.177-185
• /
• 2022

In this study, the economic feasibility of a local energy facility that uses forest biomass as an energy source was assessed. We analyzed profitability using data from the Forest Energy Self-sufficient Village Project financed by the Korea Forest Service. The energy facility has a cogeneration generator and wood chip boiler. Wood chip, which has lower heat value and is cheaper than wood pellets, is used as fuel. Revenue comes from the sale of electricity, heat, and renewable energy certificates. Additionally, we considered the sale of carbon credits as substitutes for fossil fuels. The expenditure consists of fuel costs and fixed costs, and the initial investment is treated as a sunk cost. Under the condition of a 55% operation rate and wood chip price of 95,000 KRW per ton, the annual net revenue is positive. Crucial factors for managing the facility sustainably are operation rate and fuel cost. A simulation in which two factors were changed showed that the annual net revenue is negative with a 50% operation rate and 100,000 KRW per ton of wood chip price. To improve net revenue, an increase in the operation rate or a decrease in the wood chip price is required. Additionally, selling carbon credits will make the operation of the facility more profitable. Furthermore, the payment required to procure wood chips could contribute to the rural economy. To foster the use of forest biomass for energy, the price for heat supplied from renewable energy sources should be subsidized.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1993.04b
• /
• pp.66-70
• /
• 1993

미세드릴가공은 드릴 직경의 소경화로 발생하는 공구강성저하, 지동 발생, 칩배출 곤란 등으로 인해 수많은 기계가공 중에서도 가장 어려운 가공 중의 하나이며 이로인해 설계의 단계에서 가능한 피하고있는 실정이다. 그러나 근래 각종 제품의 소형 경량화 추세가 일어나면서 미세구멍가공 기술에 대한 중요성이 높아지고 있으며, 특히 시계부품, 소형 정밀 부품, 연료분사용 노즐, 광파이버 관련품, 우주항공기 부품 등에 수요가 급증하고 있다. 또한 최근 전기.전자 공업의 발달과 함께 등장한 표면실장기술(SMT)은 프린터 배선기판의 고밀도화를 더욱 진전시켰으며 이는 구멍밀도, 구멍지름의 미소화 등 미세구멍가공 관점에서 보완해야 할 기술적인 과제를 남겨 놓았다. 본 연구는 미세드릴가공의 메카니즘을 규명하고 그 문제점을 해결하여 미소경 드릴링 머신을 개발하는 데 주력함과 동시에그 절삭현상의 기초적인 연구를 수행하였다

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.75-79
• /
• 1996

가공품 중에서 구멍가공이 차지하는 비율은 매우 높으며 또한 가공정밀도가 요구되어진다. 그러나구멍의 직경에 비하여 길이가 길어지면 칩의 배출, 절삭날부의 윤활이 어려워지고, 공구의 진동문제가있기 때문에 일반적인 가공으로는 불가능할 경우가 많다. 따라서 이에 적절한 가공방법은 고압력의 절삭유를 공급할 수 있는 공구를 이용하여 가공할 수 있으며, 그 대표적인 방법으로는 Spade Drill, Gun Drill, 및 BTA Dill에 의한 깊은구멍가공봅이다. 본 연구에서는 Single Tube BTA 드릴링 시스템에서 Single Edge BTA Drill을 사용 하여 깊은 구멍을 가공할 때 공작물 SM55C의 최적절삭 조건의 선정과 공구수명에 대하여 실험을 통하여 분석 하고자 하였다.

• Journal of Korean Society of Forest Science
• /
• v.99 no.4
• /
• pp.597-602
• /
• 2010

The most basic matter to establish forest carbon circulation village is statistic on greenhouse gas emissions. But currently, although there is statistic on greenhouse gas emissions in the level of city or province, there is not statistic on greenhouse gas emission in village unit. According to the results, The model area is located in Seobyeok-ri, Chunyang-myeon, Bonghwa-gun, Gyeongsangbuk-do, the total $CO_2$emissions caused by energy used in the model area was $1,755tCO_2$. Heating accounts for 55% of total emissions followed by 23% for power and 22% for vehicles. The model area emitted $572tCO_2$ due to rice growing and livestock raising, accounting for approximately 24.5% of total $CO_2$ emissions. It is expected that a reduction of as much as $884tCO_2$ emissions will be made from the current $964tCO_2$ to a level of 1/12th that amount, or $80tCO_2$ by replacing heating energy currently used in the model area with wood bioenergy such as wood chips or pellets. In addition, carbon emission reduction is expected for both heating and power by replacing the power consumption in houses, buildings, and street lights with solar power.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.165.1-165.1
• /
• 2016

표면활성화 접합은 이종 소재의 표면을 제어하여 직접 접합하는 기술이다. 본 연구에서는 표면활성화 접합을 이용하여 고 방열특성의 LED용 히트스프레더(heat spreader)를 제작하기 위하여 $Al-Al_2O_3$ 복합소재를 제조하였다. LED 제품의 히트스프레더는 LED에서 발생하는 열을 한 곳으로 집중하는 것을 막아 열을 분산하는 금속판을 의미한다. 최근의 LED 제품은 고출력화에 의한 발열량의 급증으로 MCL(Metal Clad Laminate)를 이용하여 LED 칩에서 발생된 열을 외부로 배출하는 모듈구조를 나타내는 경우가 대다수이다. LED에서 열이 증가하게 되면 LED의 효율이 감소하고, 수명이 줄어드는 현상을 보이기 때문에 방열특성은 매우 중요하다. 따라서 고출력화되어 LED 칩에서 발생되는 열을 제어하는 기술이 이슈화 되고 있다. 기존의 히트스프레더 구조는 통상적으로 Al/절연층(폴리머)/Al으로 폴리머의 열전도율이 1W/mk로 고출력화에 의해 급증하는 LED의 발열량을 충분히 해소시키기 어렵다. 본 연구에서는 급증하는 LED의 방열량을 해소시키기 위해서 기존의 Al/폴리머/Al의 구조를 $Al/Al_2O_3/Al$의 구조로 개발하기 위해서 HV-SCDB 기술을 이용한 $Al-Al_2O_3$ 복합소재 제조 및 접합특성에 관하여 연구하였다.

• Journal of the Microelectronics and Packaging Society
• /
• v.22 no.2
• /
• pp.5-9
• /
• 2015

Thermal management becomes serious in 3D stacked IC because of higher heat flux, increased power generation, extreme hot spot, etc. In this paper, we reviewed the recent developments of thermal management for 3D stacked IC which is a promising candidate to keep Moore's law continue. According to experimental and numerical simulation results, Cu TSV affected heat dissipation in a thin chip due to its high thermal conductivity and could be used as an efficient heat dissipation path. Other parameters like bumps, gap filling material also had effects on heat transfer between stacked ICs. Thermal aware circuit design was briefly discussed as well.