• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.93-93
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• 2017

고전력 펄스 전원공급장치를 이용한 마그네트론 스퍼터링(high-power impulse magnetron sputtering; HiPIMS)과 직류(direct current; DC) 전원공급장치를 이용한 마그네트론 스퍼터링(DC 스퍼터링)을 이용하여 제조한 티타늄 질화물(titanium nitride; TiN) 박막의 특성을 비교하였다. HiPIMS와 DC 스퍼터링 공정 중에 빗각증착을 적용하여 TiN 박막의 미세구조와 기계적 특성의 변화를 확인하였다. TiN 박막을 코팅하기 위한 기판으로 스테인리스 강판(SUS304)과 초경(cemented carbide; WC-10wt.%Co)을 사용하였다. 기판은 알코올과 아세톤으로 초음파 처리를 실시하여 기판 표면의 불순물을 제거하였다. 기판 청정 후 진공용기 내부의 기판홀더에 기판을 장착하고 $2.0{\times}10^{-5}torr$의 기본 압력까지 진공배기를 실시하였다. 진공 용기의 압력이 기본 압력에 도달하면 아르곤(Ar) 가스를 진공용기 내부로 ${\sim}10^{-2}torr$의 압력으로 주입하고 기판홀더에 라디오 주파수(radio frequency; rf) 전원공급장치를 이용하여 - 800 V의 전압을 인가하여 글로우 방전을 발생시켜 30 분간 기판 표면의 산화막을 제거하는 기판청정을 실시하였다. 기판청정이 완료되면 기본 압력까지 진공배기를 실시하고 Ar과 질소($N_2$)의 혼합 가스를 진공용기 내부로 ${\sim}10^{-3}torr$의 압력으로 주입하여 HiPIMS와 DC 스퍼터링으로 TiN 박막 제조를 실시하였다. 빗각의 크기는 $45^{\circ}$와 $-45^{\circ}$이었다. 제조된 TiN 박막은 주사전자 현미경, 비커스 경도 측정기 그리고 X-선 회절 분석기를 이용하여 특성을 분석하였다. HiPIMS로 제조한 TiN 박막은 기판 전압을 인가하지 않아도 색상이 노란색을 보이지만, DC 스퍼터링으로 제조한 TiN 박막은 기판 전압을 인가하지 않으면 노란색을 보이지 않고 어두운 갈색에 가까운 색을 보였다. TiN 박막의 경도는 HiPIMS로 제조한 TiN 박막이 DC 스퍼터링으로 제조한 TiN 박막보다 높았다. 이러한 TiN 박막의 특성 차이는 DC 스퍼터링과 비교하여 높은 HiPIMS의 이온화율에 의한 결과로 판단된다. 빗각을 적용한 TiN 박막은 미세구조 변화를 보였으며 이러한 미세구조 변화는 TiN 박막의 특성에 영향을 미치는 것을 확인하였다.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.2
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• pp.9-15
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• 2010

US NRC issued rulemaking of 10CFR50.55a to perform the Perservice and Inservice inspection for Reactor Vessel Head Penetration Nozzle of US Nuclaer plant. The rulemaking was required the EPRI Demonstration to verify the NDE technique performing special Ultrasonic examination. In order to meet this requirement, the UT and ECT procedures was demonstrated and the NDE personnel were qualified by EPRI. In this paper, the NDE technique and analysis method are described the Preservice inspection for the Palo Verde #1/2/3 Replacement Reactor Vessel Head Penetration Nozzle using the qualified procedures and personnel.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.290-295
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• 2004

In this study, the pressure vessel piping with corrosion used during long term were investigated from the time-frequency analysis method. The damage of piping could be evaluated the attenuation factor by ultrasonic parameters such as center frequency and echo waveform. Based on NDE analysis by time-frequency analysis method, it should also be possible to evaluate from various damages and defects in piping members.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.173-181
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• 2001

We calibrated a capacitance diaphragm gauge(CDG) of 1,333 Pa range by using ultrasonic interferometer manometer (UIM) that was a national low vacuum standards system. And its uncertainties were evaluated according to International Organization for Standardization(ISO), they were named to A type uncertainty, B type uncertainty, combined standard uncertainty, and expanded uncertainty, We obtained that the combined standard uncertainties were $1.38 \times10^{-2}\; Pa\sim3.03 \times10^{-1} $Pa and the relative uncertainties(combined standard uncertainty/standard pressure) were $2.3 \times 10^{-4}\;Pa\sim7.9 X\times10^{-3} $Pa for this 1,333 Pa CDG.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.2
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• pp.20-24
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• 2015

During refueling Outage, In-service inspections(ISIs) for the Nuclear Power Plant components are mandatory requirement in accordance with ASME Code Sec. XI. Especially, in current ultrasonic testing is one of the most important NDT techniques that are used for volumetric examination methods for nuclear power plant components, and accurate sizing of flaw indication by UT is essential to assure the integrity of the components. However, ASME code specifies minimum requirement for vessel examination procedure, and so far many different flaw sizing approaches have been tried to apply. Through the Round Robin Test(RRT), the accuracy of ultrasonic flaw sizing using DAC techniques was measured with the mock-ups simulating typical pressure vessel welds. These mock-ups contain artificially introduced flaws of known size and location. This paper shows experimental comparison data on the accuracy of techniques using such as 6dB drop, 50%DAC, 20%DAC and 20%DAC with beam spread correction, and also shows that diverse DAC techniques can be effectively applied to the assessment of the flaw sizing for pressure vessel welds in the stage of welding and fabrication.

• The Journal of the Acoustical Society of Korea
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• v.36 no.5
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• pp.361-369
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• 2017

Hemodynamic information in the carotid artery bifurcation is very important for understanding the development and progression mechanisms of cerebrovascular disease and for its early diagnosis and prediction of the progress. In this paper, we constructed a mock pulsatile blood circulation system using an anthropomorphic elastic vessel of the carotid artery bifurcation and ex vivo pig blood to acquire ultrasound images from blood and vessels synchronized with internal pressure while controlling the blood flow. Echogenicity, blood flow velocity, and blood vessel wall motion from the ultrasound images, and internal blood pressure were extracted over a cycle averaged from five cycles when the pulsatile pump rates are 20 r/min, 40 r/min, and 60 r/min. As a result, respectively, the peak systolic blood flow velocities were 20 cm/s, 25 cm/s, and 40 cm/s, the blood pressure differences were 30 mmHg, 70 mmHg, and 85 mmHg, the arterial walls were expanded to 0.05 mm, 0.15 mm, and 0.25 mm. Time-delayed cyclic variation of echogenicity compared to blood flow and pressure was observed, but the variation was minimal at 20 r/min. Time-synchronized cyclic variations of these parameters are important information for accurate input parameters and validation of the computational hemodynamic experiments which will provide useful information for the development and progress mechanisms of carotid artery stenosis.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.393-401
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• 2002

Pipelines in power plants, nuclear facilities and chemical industries are often affected by corrosion effects. It is important to inspect the internal defects in pipelines in oder to guarantee safe operational condition. We have taken relatively much time, cost and manpower to use conventional NDT methods because these methods are contact measuring methods. In this paper, we used digital shearography, a laser-based optical method which allows full-field measurement of surface displacement derivatives. This method has many advantages in practical use, such as low sensitivity to environmental noise, simple optical configuration and real time measurement. The experiment was performed with pressure vessels which has different internal cracks and detected internal cracks in the pressure vessels at a real time using phase shifting method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.341-348
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• 2017

This study examined the effects of the location and direction of the scolioti curve on postural balance in patients with idiopathic scoliosis. Fifteen subjects were divided into three groups: right thoracic curve group, left lumbar curve group, and double curve group. The dynamic trunk motion (angle variation in the lumbar, thoracolumbar, lower thoracic and upper thoracic region) and plantar pressure distribution (maximum force and peak pressure) were assessed using an ultrasound-based motion analysis system and Emed-at platform system. From the results, it was confirmed that patients with idiopathic scoliosis showed postural imbalance with an increased angle and pressure asymmetry according to the location and direction of the scoliotic curve for dynamic trunk motion and plantar pressure distribution. In addition, there were differences in the postural balance pattern between the single curve and double curve groups. Further studies for developing a rehabilitation training device will be conducted to improve the postural control ability and trunk balance as well as treat scoliosis based on the results of this study.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.2
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• pp.34-34
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• 1987

Friction welding has emerged as a reliable process for high-production commercial application with significant economic and technical advantages. But nondestructive test in friction weld was not clearly developed. Therefore the experimental verification is necessary in order to understand the characteristics of the pulse echo effects according to various change in welding conditions. This paper presents a new attempt to detect the bond strength of friction welds by ultrasonic. Instead of looking for a flaw or cracks at the interface, the new approach evaluates the coefficient by reflection which provides a single quantitative indicator involving the acoustic energy reflected at the interface. The objective of this study is to find the relationship between the reflection coefficients and the weld strength. Results of the bar-to-bar friction welding of aluminum to copper and stainless steel and such relationship investigation are presented and interpreted.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.2
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• pp.80-85
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• 1987

Friction welding has emerged as a reliable process for high-production commercial application with significant economic and technical advantages. But nondestructive test in friction weld was not clearly developed. Therefore the experimental verification is necessary in order to understand the characteristics of the pulse echo effects according to various change in welding conditions. This paper presents a new attempt to detect the bond strength of friction welds by ultrasonic. Instead of looking for a flaw or cracks at the interface, the new approach evaluates the coefficient by reflection which provides a single quantitative indicator involving the acoustic energy reflected at the interface. The objective of this study is to find the relationship between the reflection coefficients and the weld strength. Results of the bar-to-bar friction welding of aluminum to copper and stainless steel and such relationship investigation are presented and interpreted.