• 한국공작기계학회논문집
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• 제10권5호
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• pp.25-30
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• 2001

The purpose of this investigation is experimentally to clarify the machinability and optimum tool geometry on milling of hardened STD11 steel. In the finish process office milling of high hardened STD11 steel by CBN tool, the optimum tool shape is suggested, which can minimize the tool fracture and chipping by impact. It is measured that cutting farce, tool wear and surface roughness generated during single-insert face milling using various geometric CBN tools. It has been found that the optimal chamfer angle of CBN tool is about -$25^{\circ}C$ and the suitable chandler width is 0.2mm. The nose radius of tool is the most excellent at 1.2mm in the viewpoint of tool wear and surface roughness.

• 한국정밀공학회지
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• 제22권5호
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• pp.167-174
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• 2005

High-speed machining is one of the most effective technologies to improve productivity Because of the high speed and high feed rate, high-speed machining can give great advantages for the machining of dies and molds. This paper describes on the analysis and evaluation of cutting force in high-speed machining. Cutter rotation directions, slope directions, spindle revolution and depth of cut are control factors for cutting force. The effect of the control factors on cutting force is investigated for the high speed machining of STD11.

• 한국기계가공학회지
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• 제21권1호
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• pp.81-89
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• 2022

It is necessary to increase the surface hardness and improve the wear resistance and peeling resistance through the surface treatment and performance evaluation of the mold steel. As a result of vacuum heat treatment analysis, residual austenite measurement and surface treatment wear test, retained austenite should be removed by sub-zero treatment, and retained austenite was completely removed by treatment at -196℃. The TiMon film coated on the sub-zero treated STD11 specimen showed the lowest coefficient of friction.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.249-250
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• 2018

• 한국기계가공학회지
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• 제16권3호
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• pp.38-44
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• 2017

The technology of electrical discharge tap machining may be appropriate for making thread out of highly brittle material. Especially, it is very difficult to machine tap with the traditional method if the brittle material has been hardened by quenching. In this study, the shape of electrical discharge blind hole tap machining was analyzed by discharge time, discharge current, and the flushing hole condition after quenched the tool steel of STD11 has discharged the tap shape with a screw-shaped copper(Cu) electrode. An experimental design was planned and analyzed by Taguchi robust experimental design. The result showed that the shape of the blind hole discharge tap was influenced by the flushing hole, discharge time, and discharge current. The most important factor of the processing conditions was found to be the discharge current. When blind hole EDM with a copper electrode with a flushing hole was conducted, the discharged shape was found to be smooth and the angle of the discharged tapped thread was also found to be close to the thread angle of $60^{\circ}$. As the values of discharge time and discharge current increased, the EDMed surface coarsened due to the increase of the single discharge energy and the shape of the thread collapsing.

• Journal of Welding and Joining
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• 제33권5호
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• pp.53-60
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• 2015

Laser surface Melting Process is getting hardening layer that has enough depth of hardening layer as well as no defects by melting surface of substrate. This study used CW(Continuous Wave) Yb:YAG and STD11. Laser beam speed, power and beam interval are fixed at 70mm/sec, 2.8kW and 800um respectively. Hardness in the weld zone are equal to 400Hv regardless of melting zone, remelting zone overlapped by next beam and HAZ. Similarly, microstructures in all weld zone consist of dendrite structure that arm spacing is $3{\sim}4{\mu}m$, matrix is ${\gamma}$(Austenite) and dendrite boundary consists of ${\gamma}$ and $M_7C_3$ of eutectic phase. This microstructure crystallizes from liquid to ${\gamma}$ of primary crystal and residual liquid forms ${\gamma}$ and $M_7C_3$ of eutectic phase by eutectic reaction at $1266^{\circ}C$. After solidification is complete, primary crystal and eutectic phase remain at room temperature without phase transformation by quenching. On the other hand, microstructures of substrate consist of ferrite, fine $M_{23}C_6$ and coarse $M_7C_3$ that have 210Hv. Microstructures in the HAZ consist of fine $M_{23}C_6$ and coarse $M_7C_3$ like substrate. But, $M_{23}C_6$ increases and matrix was changed from ferrite to bainite that has hardness above 400Hv. Partial Melted Zone is formed between melting zone and HAZ. Partial Melted Zone near the melting zone consists of ${\gamma}$, $M_7C_3$ and martensite and Partial Melted Zone near the HAZ consists of eutectic phase around ${\gamma}$ and $M_7C_3$. Hardness is maximum 557Hv in the partial melted zone.

• 한국산학기술학회논문지
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• 제11권12호
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• pp.5191-5198
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• 2010

지하철 이용수요와 토지이용, 개발밀도, 환승교통체계, 접근성과 같은 다양한 역세권 특성의 관계를 규명하기 위한 많은 연구들이 추진되어 왔으나, 역세권내 보행 가로망 구조와 지하철 이용수요간의 관계에 관한 분석은 미비한 실정이다. 본 연구는 부산광역시 79개 지하철 역세권내 가로망의 구조를 공간구문론(Space syntax)을 이용하여 평가하였으며, 역세권내 가로망 구조의 접근성을 포함한 다양한 역세권 특성이 지하철 이용수요에 미치는 영향을 실증분석을 하였다. 분석결과 역세권 가로망 구조를 대변할 수 있는 공간지표인 통합도, 연결도, 명료도 중 역세권 가로망의 접근 편의성을 나타내는 통합도가 높을수록 지하철 이용수요가 증가하는 것으로 나타났다. 또한 역세권 토지이용형태와 개발밀도를 각각 반영하는 집객시설 집중도와 용적률이 높을수록 지하철 이용수요가 증가하는 것으로 나타났다. 따라서 부산광역시의 지하철 역세권 구조를 대중교통 중심의 개발 체계로 개선하기 위해서는 역세권내 보행가로의 접근성을 향상시킬 수 있는 가로 설계와 통행 목적성이 강한 도시시설물을 압축 고밀의 건축물에 조성하기 위한 노력들이 추진되어야 할 것으로 판단된다.

• 한국기계가공학회지
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• 제11권3호
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• pp.73-79
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• 2012

This paper describes the machining characteristics of the sintered carbide and die steel(STD-11) by electric discharge drilling with various tubular electrodes. Electrical discharge machining(EDM) removes material from the workpiece by a series of electrical sparks that cause localized temperatures high enough to melt or vapourize the vicinity of the charge. In the experiment. four types of electrode which have different diameter are used with the application of continuous direct current and axial electrode feed. The controlled factors include the dimension of the electrode. In drilling by EDM, the dielectric flushed down the interior of the rotating tube electrode, in order to order to facilitate the removal of machining debris the hole. The expansion increase with increasing the thickness of material and the diameter of electrode and the expansion of sintered carbide is 1.75 times large then that of die steel. The taper of machined hole decrease with increasing the thickness of material. The crater sixe of die steel is larger then thet of sintered carbide and the surface roughness of sintered carbide is 1.58 tims larger then that of die steel.

• 전기의세계
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• 제38권9호
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• pp.11-17
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• 1989

본고에서는 국제 규격에 있어 국제기구인 CISPR와 국가규격으로는 미국, 서독, 영국, 캐나다, 일본 그리고 특수한 규격으로 MIL-STD와 TEMPEST 규격에 관하여 살펴보고자 한다. EMI에 대한 국제규격은 초기에는 국제 무선 항행, 통신 및 서비스의 보호라는 차원에서 출발하여 최근 정보기기의 범람에 의한 제어 시스템에 의해 가능성에 대한 안전보장과, 본고에서는 언급되지 않으나 때로는 인체의 위해(Hazard)를 방지하기 위한 경우, 또 특별한 분야로써 중요 정보의 누출 보호(TEMPEST)기술 등 다양한 분야로 확대되고 있다.

• 열처리공학회지
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• 제14권2호
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• pp.81-88
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• 2001

The effects of post-oxidation and sulfnitriding treatments on the phase transformation in the nitrided case of tool steels have been studied. Dense and compact $Fe_3O_4$ layer was formed at the outer surface of nitride compound layer by post-oxidation treatment and multi layer of iron sulfide(FeS) was formed in the compound layer by sulfnitriding treatment. The surface hardness decreased because of formation of the soft oxide or sulfide at the nitride surface. Diffusion layer of nitride case was not affected by post-oxidation treatment or sulfnitriding treatment of nitrided alloy tool steels.