• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.59-59
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• 1996

막분리에 의한 폐윤활유 재생공정을 개발하기 위한 기초 연구로써 폐윤활유 분리/재생용으로 적합한 복층(multilayer)세라믹 복합막의 제조와 합성막의 폐유 분리 효율등이 연구되었다. 결함이 없고 두께가 균일한 지르코니아 복합막 (기공크기 0.07 $\mu$m 이하)은 압출 성형법으로 제조한 튜브형 $\alpha$-알루미나 담체 (외경 7.8 mm, 두께 0.6 mm, 기공크기 0.7 $\mu$m)내부표면에 역침지 인상법(reverse dip-drawing technique)에 의하여 지르코니아 슬러리를 코팅 한 후 950$\circ$C에서 1시간 열처리하여 제조 되었다. 또한 지르코니아 복합막 위에 니타니아 졸-겔 코팅을 한 후 450$\circ$C에서 2시간 열처리하여 기공크기가 15 nm정도인 3층 복합막을 제조 하였다. SEM, Bubble Point Test, Mercury Porosimeter 그리고 분획 분자량 측정등에 의하여 복합막의 코팅층 두께, 결함유무 및 막의 기공크기등을 분석하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.2
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• pp.190-201
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• 1985

Direct cutting tests was carried out to evaluate the dynamic performance of lathes under various cutting conditions. Significant factors influencing the chatter limits were identified through use of analysis of variance. Dynamic performances of two lathes were compared and the merits and drawbacks of the direct cutting test were discussed. Exciting-direct-cutting test method was newly proposed as a more rational method of dynamic performance test. The basic theory and experiments of the test were explained. The results shows that the method can be used as a powerful tool for the evaluation and the improvement of dynamic performance of machine tools.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.468-473
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• 2017

This paper presents an in-process measurement system for shaft radius measurement during grinding process. This system does not require to stop the grinding process, which can enhance productivity and quality. In order to measure the radius, the system employs an eddy current sensor that can measure without any contact with the shaft. This type of sensor is very appropriate because it is insensitive to interference such as cutting fluid, coolant, contact pressure, and wear. For data analysis, the measurement system is modeled as a linearized discrete form where the states with noise are estimated by an extended Kalman filter. This system has been validated through simulations and experiments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1429-1436
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• 2011

In this paper, a new tube-radius-measuring algorithm has been proposed for effectively measuring the radii of small tubes under severe noise conditions that can also perform well when metal scraps that make it difficult to measure the radius correctly are inside the tube hole. In the algorithm, we adopt a fuzzy searching method that searches for the center of the inner circle by using fuzzy parameters for distance and orientation from the initial search point. The proposed algorithm has been implemented and tested on both synthetic and real-world tube images, and the performance is compared to existing circle-detection algorithms, such as the Hough transform and RANSAC methods, to prove the accuracy and effectiveness of the algorithm. From this comparison, it is concluded that the proposed algorithm has excellent performance in terms of measurement accuracy and computation time.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.81-84
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• 2004

자궁암 치료시 고선량률 강내 근접치료기와 병행하여 사용할 초음파 온열 치료기가 개발되었다. 온열치료기는 텐덤형, 오보이드 형, 원통형으로 디자인 되었다. 각각의 치료기들에 사용될 초음파원 으로 PZT물질이 사용되었다. 텐덤형의 경우 외부직경이 2mm 이고 길이가 24.5mm 인 PZT5A가 사용되었고 오보이드형은 직경 20mm, 길이 20mm 인 원통형의 PZT 8 물질을 반으로 나누어 사용하였으며 원통형 치료기는 외경 25.4mm, 길이가 15.2 mm 인 원통형 PZT 8물질이 이용되었다. 각각의 트랜스듀서의 초음파 발생효율을 측정하였다. 텐덤형의 경우 3.2MHz 로 작동하였고 평균효율성은 16.7% 이다. 오보이드형의 작동 주파수는 1.5MHz 이며 효율성을 32${\sim}$46% 이다. 마지막으로 원통형의 작동주파수는 1.7MHz 이며 측정?? 효율성의 범위는 55${\sim}$65%이다. 특성분석 결과 온열치료에 사용될 초음파원으로 사용가능함이 입증되었다. 따라서 3개의 텐덤형 드랜스듀서를 연결하여 자궁내막의 길이가 73.5mm까지 치료가능한 텐덤형 온열치료기가 제작되었고 2개의 반원통형 트랜스듀서를 연결하여 치료길이가 40mm 인 오보이드형 치료기가 제작되었다. 마지막으로 4개의 원통형 트랜스듀서를 연결하여 질암등에 사용이 가능하고 61mm 까지 치료가 가능한 원통형 온열 치료기가 제작되었다.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.4
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• pp.294-303
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• 2005

This paper describes the analysis results of a series f Round-Robin test that was performed to intercompare inspection and diagnosis techniques for characterization of pressure tube f a pressurized heavy water reactor under the Coordinated Research Project(CRP) of IAEA's nuclear Power Programme. For this test, six nations, Korea, Canada, India, Argentina, Rumania, and China that currently have pressurized heavy water reactors under operation involved, and the "KOR-1" pressure tube sample prepared by Korea was used. Two kinds of NDE technique, ultrasonic and eddy current test, were applied for these tests. The "KOR-1" pressure tube sample contains total 12 artificial flaws such as crack-like EDM notches, wear that is similar to the real flaws and can be produced on the pressure tubes during plant operation. Test results showed that seven laboratories from six nations detected all twelve flaws in "KOR-1" specimen by using ultrasonic and eddy current test methods, and ultrasonic test method was more accurate than eddy current test method in flaw detectin and sizing. ID flaws in pressure tube sample were more easily detected and accurately sized than OD flaws.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.907-914
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• 2018

Wireless charging has been actively researched and popularized owing to the potential convenience of being able to charge electronic devices without wires for users. However, the receiver on the wireless charging pad is not charged when the center of the receiver is misaligned; thus, the center of the receiver must be adjusted well. This misalignment may greatly reduce the convenience of wireless charging. To overcome this limitation of wireless charging, a coil is designed to improve the positional freedom of the receiver. The positional freedom of the Rx coil is improved when the outer diameter of Tx coil is larger than when Rx and Tx coils are almost the same size. When the Tx coil has a larger outer diameter than that of the Rx coil, the efficiency at the center is somewhat lowered, but the efficiency is improved compared to when the center is out of order. In this paper, a double coil structure having an outer and an inner coil is proposed. The double coil structure further improves the efficiency, compared with one coil with the same outer size. The simulation and measurement results demonstrated that the tendency was consistent, and it was verified that the degree of freedom of the Rx coil is improved by adding the inner coil, while the size of the outer coil was the same. The measurement shows that the transmission efficiency of the conventional Tx coil is 37 %, the larger outer diameter coil is 45 %, and double coil is 47 % when the distance of the Tx/Rx coil is 3 mm, the misalignment is 15 mm and current flowing in the Rx coil is 1 A at an operating frequency of 105 to 210 kHz.

• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.76-80
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• 2014

Toroidal cores made of metallic powder requires large magnetic field strength up to few decade kA/m to obtain major hysteresis loop. To overcome thermal heat generation problem from large exciting current during measurement, we have employed a real time hysteresis loop tracer which can digitize and calculate B-H signals in personal computer as real time. For example, when we magnetize specimen at 10 Hz frequency, we could display hysteresis loops 10 times per second. Using the real time hysteresis loop tracer, we could measure major hysteresis loop of toroidal shape metallic powder core at maximum flux density or maximum magnetic field strength to be measured within 5 second not to significant increasement of specimen temperature due to the heat dissipation from coil windings. For the constructed hysteresis loop tracer, we could measure hysteresis loop at magnetic field strength higher than 50 kA/m for the toroidal shape specimen.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.4
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• pp.521-526
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• 2012

The performance of arrow from a manufacturing process depends on arrow's trajectory(archer's paradox) and intensity of an impact points. Especially, when conducting a shooting experiment over and over in the same experiment condition, the intensity of impact point is an objective standard to judge the performance of the arrow. However, the analysis method for the impact point is not enough, a previous research of the arrow's performance has been focused on a skill to optimize a manufacturing variables(feathers of an arrow, barb of an arrow, arrow's shaft, weight, external diameter, spine). In this paper, We propose measurement system of arrow's impact point with Mamdani fuzzy inference system and similarity of polygon for automation of impact point's measurement. Measuring the impact point data of the arrow moving with a high speed(approximately 275km/h) by using line laser and photo diode array, then the measured data are mapped to arrow's impact point with fuzzy inference and similarity of polygon.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.177-177
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• 1993

뇌모세혈관내피세포로 구성된 혈액-뇌관문(BBB)은 tight junction으로 구성되어 있을뿐만 아니라 fenestra가 없는 등 BBB가 가진 특성으로 인해 물질 수송에 장벽역할을 하기 때문에 주로 중추신경계 질환시의 약물요법에 많은 제한이 따른다. 따라서 뇌로의 효율적인 약물 송달방법에 대해 많은 연구가 진행중에 있는데 본 연구에서는 BBB의 hyperosmotic opening법을 이용하여 뇌로 잘 수송되지 않는 약물의 뇌송달 방법에 대해 연구하고자 하였다. 먼저 수용성으로 인해 BBB 에 잘 통과하지 않는 물질로 신장 및 뇌영상 촬영시 사용되는 방사성 의약품이 Tc-DTPA를 이용하여, hyperosmotic opening법에 의한 뇌투과 증가정도를 검토하였으며, 실험방법이 확립됨에 따라 뇌암의 항암요법을 위해 뇌로의 투과가 적은 항암제(5-Fluorouracil, 5-FU)의 뇌송달에 대해 본 방법을 적용하여 검토하였다. 실험동물로는 S.D.계 웅성 랫트를 사용하였으며, 실험방법은 다음과 같이 하였다. 랫트의 좌측 외경동맥(left external carotid artery)에 혈류의 역방향으로 혈관 분지점에서 1-2mm 전까지 PE-50 catheter를 삽입하고, 1.6 molal L－(＋)－ arabinose 고장액(1580mOsm)을 0.12ml/sec의 일정한 속도로 30초간 infusion함으로 BBB를 opening 한 다음, 5분 후에 Tc-DTPA를 대퇴 정맥으로 주사하여 0, 10, 30초, 1, 1.5, 2, 3, 4, 5, 7 및 10분 간격으로 대퇴동맥에 설치한 카테타로부터 혈액을 채취하고 마지막 혈액을 취한 후 즉시 단두하여 뇌를 적출하였다. 채취한 뇌를 액체질소에 담근 후 tissue Tek으로 고정하고 autoradiography를 하기 위한 slice와 농도측정을 위해 필요한 부위를 취한 후 감마카운터로 Tc-DTPA의 brain각 부위별 및 혈장농도를 측정하였다. 뇌조직중 혈액부피의 측정은 Tc-albumin를 이용하여 구하였다. 같은 방법으로 5-FU에 대한 실험도 행하였고, 이때 각 혈장 및 조직중의 5-FU함량은 HPLC로 하였다.