• 한국정밀공학회지
• /
• 제5권4호
• /
• pp.59-65
• /
• 1988

This paper describes the transmutation layer of CNC Wire electrical discharte machined surface. In order to analayze and invesigate transmutation layer of the carbon tool steel, workpieces was heat-treated by quenching, tempering, normaling. The obtained results are summarized as follows. 1. The result showed that wire electrical discharge machined surface region was transmuted into the recdast layer in the range of about 10${\mu}$m deep by resolidification and next zone was transmuted into the heat affected zone in the range of about 15${\mu}$m deep by high temperature. 2. The hardness of the recast layer and heat affected zone was decreased on its machined surface. 3. The more wire feedrate was increased, the more electrical discharge machine gap was decreased.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1997년도 추계학술대회 논문집
• /
• pp.279-282
• /
• 1997

The propose of this study is research and improvement of LiNiO$_2$as cathode material for Lithium secondary batteries. LiNiO$_2$is prepared by heating LiOH . $H_2O$ and Ni(OH)$_2$(mole ratio 1 : 1) on various heat condition. In the result of XRD mesurement, all LiNiO$_2$prepared at this study showed hexagonal structure. In Cyclic Voltammetry, LiNiO$_2$is not conspicous about oxidation peak but oxidation curve change steeply over 3.8V and reduction peak discover at 3.6V. In discharge capacities, specific capacity is higher $O_2$than air when preliminary heated and 75$0^{\circ}C$ than $700^{\circ}C$, 80$0^{\circ}C$ when heated. Therefore, when preliminary heat at $650^{\circ}C$ $O_2$and heat at 75$0^{\circ}C$ carried out, discharge property is the best.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.693-698
• /
• 2002

For the evaluation of the plasma display panel (PDP)'s noise, vibration and sound characteristics of fanless PDP are measured and investigated. PDP is a type of two-electrode vacuum tube which operates on the same principle as a household fluorescent light. An inert gas such as argon or neon is injected between two glass plates on which transparent electrodes have been formed, and the glass is illuminated by generating discharge. For this discharge, both high voltage and currents are needed and cause an acoustic noise. We investigated the noise characteristics connected with both a electromagnetic elements from SMPS to panel through X, Y and logic board, and a mechanical elements form panel to case through transfer path which related with vibration and heat. To reduce the noise of PDP, a discharge pulse memory design related with both higher brightness and lower power consumption is important and mechanical characteristics connected with dissipation process of both heat and vibration generated by panel discharge must be investigated.

• 한국연소학회지
• /
• 제6권1호
• /
• pp.1-6
• /
• 2001

To evaluate the effect of lobed structure on pollutant emission, an experimental study examines NOx and CO emissions associated with four burner geometries, such as a conventional circular burner and three lobed ones. Rapid mixing allowed by the lobed burner to produce lean premixed flames, with narrower flame stability diagram than for the conventional circular one. Conventional circular burner of wide and uniform burner rim has an advantage of flame stabilization. Correlation on fuel discharge velocity for flame blowout should be included a variable related to the wall effect of the burner. NOx emission reduces by about 5% at the burner with lobed structure in fuel discharge side compared to conventional circular one. This is due to lower flame temperatures through flame elongation and increased radiative heat losses, caused by partially luminous flame in flame front. Meanwhile, at the burner with lobed structure in air discharge side and both fuel and air discharge sides, NOx emission somewhat increases with reduced radiative heat losses in spite of flame elongation. Therefore, the rapid mixing by lobed structure does not always have an advantage on NOx reduction.

• 한국표면공학회지
• /
• 제56권6호
• /
• pp.386-392
• /
• 2023

In this work, we describe the reduction kinetics of gold nanoparticles synthesized by plasma discharge in aqueous solutions with varied voltages and precursor (HAuCl₄) concentrations. The reduction rate of [AuCl₄]^- was determined by introducing NaBr to the gold colloidal solution synthesized by plasma discharge, serving as a catalyst in the reduction process. We observed that [AuCl₄]^- was completely reduced when its characteristic absorption peak at 380 nm disappeared, indicating the absence of [AuCl₄]^- for ligand exchange with NaBr. The reduction rate notably increased with the rise in discharge voltage, attributable to the intensified plasma generated by ionization and excitation, which in turn accelerated the reduction kinetics. Regarding precursor concentration, a lower concentration was found to retard the reduction reaction, significantly influencing the reduction kinetics due to the presence of active H⁺ and H radicals. Therefore, the production of strong plasma with high plasma density was observed to enhance the reduction kinetics, as evidenced by optical emission spectroscopy.

• KIEAE Journal
• /
• 제1권1호
• /
• pp.45-52
• /
• 2001

This study aims to make a fundamental data for a policy-making decision in treatment and disposal of municipal solid wastes and presents a research data on the discharge properties of municipal solid wastes and making a unit of them in the Taegu metropolitan city. The results can be summarized as follows; survey the discharge properties of municipal solid wastes, calorific values and to present a research-data in supplying incineration-heat of wastes with the area of Sung-seo in Taegu. So, using fundamental data for planning and running wastes-incineration plants as well as trying to make better Urban Environmental Infra-structure. The results are obtained from the study. 1) The proportion of combustible wastes in Taegu increased from 89.6% to 94.47% during 1993~2000. However, the proportion of incombustibles decreased from 10.4% to 5.53% during 1993~2000. 2) The value of representative properties is about 1500~2000kcal/kg. So we can expect that it should be made use of energy-resources positively. 3) The heat from Sung-seo wastes-incineration plants is used to produce electronic-energy for wastes-incineration plants in summer season. The heat from Sung-sea wastes-incineration plants is in charge of 27% which of supplying the area of Sung-seo with district heating energy in winter season.

• 한국산학기술학회논문지
• /
• 제18권9호
• /
• pp.61-67
• /
• 2017

프레스금형 제작 시 사용목적에 맞는 적합한 소재선택과 빠른 가공방법에 대한 연구는 금형제작시간을 줄이고 금형원가를 절감하는데 절대적으로 필요한 연구분야이다. 특히 장수명 프레스금형을 개발하기 위해선 열에 대한 고찰이 반드시 이루어져야 한다. 일반적으로 프레스금형의 주요부품 소재로는 Cr, W계 저합금 공구강, 고탄소 고크롬강, 고속도강 등 냉간 금형용 합금공구강이 많이 쓰이고 있다. 프레스금형부품을 가공하는 데는 주로 공작기계와 와이어 컷 방전가공을 사용하고 있다. 가공공정에 따라 금형부품의 가공시간 및 수명이 많은 차이가 난다. 밀링가공과 연삭가공으로 제작된 부품의 경우 제작시간과 비용은 많이 드는데 비해 금형의 수명이 길고 밀링가공과 와이어 컷 방전가공을 사용하면 제작시간과 비용은 절감되는 반면 금형수명은 줄어드는 현상이 나타난다. 따라서 본 연구에선 가공시간과 비용이 절감되는 가공방법으로 열처리를 사용하여 금형의 사용수명을 향상시키는 방법에 대해 고찰하고자 한다. 밀링가공-연삭가공, 밀링가공-와이어 컷 방전가공, 밀링가공-와이어 컷-고온템퍼링, 3가지 가공방법으로 시편을 제작하여 가공표면과 중심부를 SEM, EDS분석 및 표면조도분석으로 문제점을 고찰하였고 밀링가공-와이어 컷 방전가공-고온템퍼링의 가공방법으로 밀링가공-연삭가공과 동일한 금형의 수명을 만드는 방법을 도출하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1865-1868
• /
• 2003

This paper provides a new method for hybrid machining, particularly suited to micro fabrication applications such as micro point, micro line, micro structure, micro partition and so on. Developed micro fabrication process by electrical discharge machining (EDM) and electrical discharge deposition (EDD) with metal powder (Ti, Fe) has been studied to build TiC or FeC structure. Titanium powder or iron powder is supplied from working fluid (kerosene or de-ionized water with powder) and adheres on a workpiece by the heat and electric power caused by the electrical discharge. The use of a tool electrode is expected to keep powder concentration high in the gap between a workpiece and a tool electrode and to accrete powder material on the workpiece. The deposition is tried under various electrical conditions (workpiece. tool electrode, working fluid, discharge current, voltage and powder etc.). On the other hand. using electrical discharge machining (EDM) with the same tool electrode, it can be used as a removal process (cutting) by electro erosion at the same time. Therefore. this new method can do a hybrid machining to build up and down a structure with the workpiece.

• 혜화의학회지
• /
• 제8권2호
• /
• pp.259-272
• /
• 2000

About the acupuncture & moxibustion therapy of allergic rhnitis, nasal discharge(鼻涕), stuffy nose(鼻塞), and rhinorrlea with turbid discharge(鼻淵), the results are obtained as follows: 1. It appeared that the reasons for allergic rhnitis are the lung's contacting to Wind-Coid(風寒), Damhwa(痰火), and accumulated fever of stomach, the reasons for nasal discharge(鼻涕) is the Cold-Hot of a lung. the reasons for stuffy nose(鼻塞) is the harmonization of the Lung(肺氣), the reasons for the rhinorrlea with turbid discharge(鼻淵) are the heat of the Brain(腦熱), heat of the Gallbladder(膽熱), most probably. 2. When we do a acupuncture & moxibustion therapy for the allergic rhnitis, we used P'ungmun(風門), Shinjong(神庭), mostly. For the nasal diacharge(鼻涕) ; Yonghyang(迎香), P'ungmun(風門), Sangsong(上星) and Sugu(水溝) were the most useful acupuncture point. For the stuffy nose(鼻塞) ; Sangsong(上星), Yonghyang(迎香), Hapkok(合谷), and Sugu(水溝) were used most frequently. For the rhinorrlea with turbid discharge(鼻淵); Sangsong(上星), Hapkok(合谷), Yonghyang(迎香), and P'ungji(風池) were the best acupuncture point. 3. Concerning the frequencies of the acupuncture & moxibustion therapy for these four symptoms, Bladder Meridian(膀胱經) and Governor Vessel Meridian(督脈) were the most useful ones. As to the acupuncture point, Sangsong(上星), Yonghyang(迎香), Sugu(水溝) and Hapkok(合谷) were used most repeatedly.

• Advances in aircraft and spacecraft science
• /
• 제4권4호
• /
• pp.437-448
• /
• 2017

The problem of flow through the vent is formulated as an unsteady, nonlinear, ordinary differential equation and solved using Runge-Kutta method to obtain pressure inside payload faring. An inverse problem for prediction of the discharge coefficient is presented employing measured internal pressure of the payload fairing during the ascent phase of a satellite launch vehicle. A controlled random search method is used to estimate the discharge coefficient from the measured transient pressure history during the ascent period of the launch vehicle. The algorithm predicts the discharge coefficient stepwise with function of Mach number. The estimated values of the discharge coefficients are in good agreement with differential pressure measured during the flight of typical satellite launch vehicle.