• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.509-510
• /
• 2006

Correlations between in-flight particle, splat and coating microstructure of thermally sprayed Ni20Cr were investigated. Flame spray and arc spray systems were employed for spraying Ni20Cr powder and Ni20Cr wire, respectively. The results showed that the arc spray process produced a broader size distribution for both in-flight particles and splats compared to flame process. Flower-like splat morphology was obtained from the arc spray whereas a pancake-like splat was obtained by flame spray. Ni20Cr coating sprayed by arc process had a denser microstructure, lower porosity and better adhesion at the interface.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1993년도 하계학술대회 논문집 B
• /
• pp.627-630
• /
• 1993

The arc characteristics have influences on the current interruption phenomena in the regimes of low current as well as high current. It is very important to understand the arc characteristics for the initial design of a circuit breaker. This article describes the theoretical analysis of the arc characteristics by means of arc energy integral method when convection dominated low current arcs are produced in the dual-nozzle air and $SF_6$ gas flows of a model interrupter. The arc radius, average electric field strength and arc voltage have been investigated at the current range of 60 to 230 A and at the upstream pressure of 0.6 MPa in both air and SF6 gas. The results have been compared to show the difference of both gases and the trends similar to those of other investigations.

• Journal of Welding and Joining
• /
• 제8권1호
• /
• pp.23-30
• /
• 1990

The robotic welding has been adapted positively in many welding shops forthe purpose of improving the welding efficiency and liberating operators from the severe working atmosphere. But for a large-size structure with thick plates like ship-building and every kind of plants manufacturing, the application of the arc welding robots is not established yet. The reason is assumed that the conventional arc welding robots are not adaptive for multi-pass welding of thick plates whose grooves are not so accurate. As one solution to this problem, a guidance system which uses the welding arc itself as a sensor is largely used. In this study the velocity controller which changes the tip to workpiece distance for regulating the weld proposed. The proportional and integral gain of velocity controller were determined by using the computer simulation of the control system, and the simulation results compared with the experimental ones. It was revealed that the developed control system using the arc sensor principle has a good capability of tracking the weld joint, although some more studies will be needed to refine the model of arc current.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
• /
• pp.361-365
• /
• 2002

Advancements in silicon phase control (SCR) technologies provide an arc welding power supply that has the capability to allow the alteration of the Alternating Current (AC) welding output. These technologies provide a square wave output involving sixteen frequency selections and multiple balance selections. While an AC out put is known to minimize magnetic disturbances associate with Direct Current (DC), the potentials of a non-sinusoidal waveform have not been explored. The focus of the paper is to determine the effects that the frequency and balance of an AC wave form output will have upon a high speed Submerge Arc (SAW) application. The test matrix of the project includes welding .250" steel plate. Joint type is square groove with a travel speed of 65 IPM. Each of the weld parameters was held constant, only the frequency and/or balance were altered between welds. Each frequency/balance combination involved three-gap spacing. Upon completion of the welds the bead profiles were measured and recorded. A relationships/trends were observed with various frequency and balance values. Optimum frequency and balance values were found for the .250" square groove application which permit consistent weld sizing, ease of slag removal, and minimal plate distortion.

• 한국경영과학회지
• /
• 제18권1호
• /
• pp.29-43
• /
• 1993

This paper condisers a problem of determining arc capacities for a communication network with fixed-charged linear arc-cost functions, which is known to be NP-hard. For the problem, an efficient heuristic solution procedure is derived. The procedure is further shown working well for designing arc capacities of a network in a situation where the network needs to be extended by connecting its nodes to some new nodes or where the network needs to be extended by expanding its arc capacities.

• 전기의세계
• /
• 제22권2호
• /
• pp.57-69
• /
• 1973

The aim of this study was to investigate the behaviors of plasma jet under coaxial magnetic field in paralled with it for controlling optical characteristics and input power of plasma jet without impurity and instability of arc plasma column. Because the discharge characteristics of plasma jet were so distinctively different according to the existence or non-existence of magnetic field, the input power, luminous intensity of plasma jet and thermal efficiency were comparatively studied in respect of such variables as arc current, gap of electrode, quantity of argon flow, magnetic flux density, diameter and length of nozzle, with the use of several materials which were different in diameter and length of nozzel. The results were as follows; 1) The voltage tends to show a drooping characteristic at law current and then rises gradually. The luminous intensity of plasma jet increases exponentially with arc current. 2) Arc voltage increases and luminous intensity tends to decrease gradually as gap of electrode increases. 3) Arc voltage and luminous intensity tends to decrease gradually as gap of electrode increases. 3) Arc voltage and luminous intensity increase in accordance with the quantity of argon flow. 4) At first step, arc voltage increases to maximum value with the growth of flux density and then tends to show a gradual decrease. Luminous intensity decreases with the growth flux density. 5) Arc voltage decreases as the constriction length of nozzle increases, maximum decrease is shown at the constriction length of 20(mm) and it increases beyond that value. The luminous intensity decreases as the constriction length grows. 6) Arc voltage and luminous in tensity increase with the growth of diameters of nozzle. 7) Thermal efficiency has values between 50% and 75%, being influenced by arc current, the quantity of argon flow, flux density, the length of electrode gap and the constriction length of nozzle.

• 미생물학회지
• /
• 제52권2호
• /
• pp.192-201
• /
• 2016

최근 북극해의 축치해(Chuckchi Sea)로부터 저온지질분해 효소활성을 보이는 Psychrobacter sp. ArcL13 균주가 분리되었다. 그러나 낮은 발현 양 때문에, 이 효소의 다양한 분야에서의 활용에 제약을 받아왔다. 따라서 유전자 재조합 기술을 이용하여, 이 효소를 대량생산하는 기술개발이 필요하였다. 재조합 지질분해효소를 만들기 위해서는 우선 해당 유전자의 동정이 필요하였기 때문에, Psychrobacter sp. ArcL13 균주로부터 PCR을 이용한 gene prospecting 방법으로 새로운 지질분해효소 유전자인 ArcL13-Lip을 분리하고 전체 염기 서열을 규명하였다. 염기 서열 분석결과 ArcL13-Lip은 일부 Psychrobacter 속 박테리아 유래의 지질분해효소들과 염기 서열의 유사성은 낮지만, 84-90%의 아미노산 서열 유사성을 보였다. ArcL13-Lip 전체 유전자를 대장균에서 발현시키고 전기영동으로 분석한 결과, 재조합 ArcL13-Lip은 약 35 kDa의 분자량을 보였으며 단백질 봉입체 형태로 발현되었다. Unfolding된 ArcL13-Lip을 다양한 첨가물이 포함된 완충용액에서 refolding 시킨 결과, glucose에 의해서 refolding 효율이 가장 크게 증가하였다. Refolding된 재조합 ArcL13-Lip은 다양한 p-nitrophenyl ester 중 p-nitrophenyl caprylate과 p-nitrophenyl decanoate에 대해 가장 높은 효소활성을 보였다. 온도에 따른 효소활성을 조사한 결과 ArcL13-Lip은 $40^{\circ}C$에서 최고의 활성을 나타내었고, $10^{\circ}C$와 $20^{\circ}C$에서 각각 최고 활성 대비 약 40%와 73%의 효소활성을 나타내었다. 이와 같이 ArcL13-Lip은 전형적인 저온활성 효소의 특징을 보여주었다.

• 한국세라믹학회지
• /
• 제43권7호
• /
• pp.408-414
• /
• 2006

Properties of slag cement that contained 50 wt% of blast furnace slag were studied when replaced blast furnace slag powder with electric arc furnace slag powder. Electric arc furnace slag was aged for about 2 months in the air by being crushed to be 1-3 mm in size. As a result of the experiment, it was proven that the water content for obtaining the same consistency became decreased as slag is replaced with electric arc furnace slag instead of blast furnace slag. Also, the workability of mortar increased about 30% at the same ratio of water to binder when blast furnace slag was completely replaced with electric arc furnace slag. The compressive strength of mortar on the 28 days increased when a slag replacement rate became 10 wt%, however, it rather decreased when the slag replacement rate exceeded 10 wt%. The heat of hydration became higher for the first 14 h in case of the replacement of slag cement by electric arc furnace slag. Yet, it decreased when 14 h had passed. Therefore, when all blast furnace slag was replaced with electric arc furnace slag, about 15 cal/g heat of hydration decreased when it passed about 72 h.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2011년도 추계 학술논문 발표대회
• /
• pp.243-244
• /
• 2011

In general, magnetite or barite (density: more than 4.0ton/㎥) has been used in concrete for radiation shielding, and radiation tests have been performed to evaluate shielding performance. However, researchers have not studied concrete for radiation shielding that utilizes electric arc furnace oxidizing slag. This research aims to utilize electric arc furnace oxidizing slag which depends on reclamation as environment-friendly concrete materials by using coarse and fine aggregates of electric arc furnace slag containing 30% ferrous metal and with a density of around 3.0~3.8 ton/㎥. Accordingly, this research has judged that the high density electric arc furnace oxidizing slag aggregate can be applied to radiation shielding concrete. It has also examined the possibility of developing radiation shielding concrete utilizing electric arc furnace oxidizing slag aggregate by comparing concrete utilizing all fine and coarse aggregate of electric arc furnace oxidizing slag with concrete using magnetite.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제15권2호
• /
• pp.123-135
• /
• 2011

In this paper, we present arc-length estimations for quadratic rational B$\acute{e}$zier curves using the length of polygon and distance between both end points. Our arc-length estimations coincide with the arc-length of the quadratic rational B$\acute{e}$zier curve exactly when the weight ${\omega}$ is 0, 1 and ${\infty}$. We show that for all ${\omega}$ > 0 our estimations are strictly increasing with respect to ${\omega}$. Moreover, we find the parameter ${\mu}^*$ which makes our estimation coincide with the arc-length of the quadratic rational B$\acute{e}$zier curve when it is a circular arc too. We also show that ${\mu}^*$ has a special limit, which is used for optimal estimation. We present some numerical examples, and the numerical results illustrates that the estimation with the limit value of ${\mu}^*$ is an optimal estimation.