• 한국정밀공학회지
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• 제16권1호통권94호
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• pp.132-140
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• 1999

This paper suggests a monitoring method for the pulsed laser spot welding of the thin metal sheets using a point IR(InfraRed) sensor. A new criterion was introduced and the experimental results guaranteed the efficiency. The ideal radiation feature was derived from the mathematical model and was simulated. The radiation feature is robust to withstand the change of measuring condition and can be used to detect the absorbed laser energy. In an experiment, the radiation feature was examined for the differect laser energy. The pulse width and the laser power was variated and the radiation feature was examined. In the other experiment, the relationship between the weld strength and radiation feature was examined. Artificial Neural Network(ANN) was employed to find out the relationship. The correlation coefficient between the real strength and the estimated strength is high as 0.94 and the mean square error is low as 0.64 kgf learned parts. Another group of the welds was used to appraise the learning efficiency. The correlation coefficient between the measured and the estimated weld strength is high as 0.91.

• Nuclear Engineering and Technology
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• 제31권4호
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• pp.423-431
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• 1999

A radiotracer technique has been developed to monitor the rotational movement of two piston rings in one cylinder during engine operation. The rings were labeled with two different kinds of radioisotopes, i.e. $^{60}$ Co and $^{192}$ Ir, for identification of the top ring from the second ring. The radiotracers were implanted in a small hole bored on the inner side of each piston ring. The rings were installed in a single cylinder hydrogen engine and three Nal scintillation detectors were mounted around the engine block to measure the gamma radiation. The angle of ring-gap orientation was determined from the radiation counts measured with the three detectors during engine operation. Two windows (upper window for $^{60}$ Co and lower window for $^{192}$ Ir) were set on each ratemeter to count radiation from the two isotopes separately. Procedure to convert the radiation counts to the position of the ring gap was established. With the software programmed with MS-Visualbasic, radiation counts were compared with the reference responses that were measured at angular intervals of 10$^{\circ}$for each piston ring in advance of the experiment. The result was used for the evaluation of the relationship between the orientation of ring-gaps and oil consumption. It was found that an increase in the oil consumption rate of a specific operation condition was closely related to the relative phase angle of the two piston rings.

• 한국안전학회지
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• 제18권2호
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• pp.50-55
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• 2003

Radiation degradation of crosslinked polyethylene(XLPE) was investigated using thermogravimetric analysis(TGA), The results of TGA were compared with FT-IR, melting temperature, oxidation induction time, and elongation at break on the XLPE exposed by $\gamma$-ray. 5% decomposition temperature of $\gamma$-ray irradiated XLPE showed similar tendencies with the case of elongation at break. Both properties agreed below 1000 KGy, however, did not show any remarkable characteristics above 1000 kGy, these properties can be useful to evaluate the radiation degradation of XLPE for only low irradiated region. Above 1000 kGy, the thermal decomposition activation energy showed decreased, on the contrary, increasing below 1000 kGy. Compared with FT-IR spectrum of irradiated XLPE, it was confirmed that the oxidation reaction was still occurring below 1000 kGy. Radiation degradation of XLPE was dependent upon the irradiation doses, TGA can be a useful tool to evaluate the degradation.

• 한국전기전자재료학회논문지
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• 제13권11호
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• pp.938-942
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• 2000

Radiation effects on dielectric properties of low density polyethylene(LDPE) were investigated using the various measurements of FT-IR, gel content and elongation at break. FT-IR spectra showed that polar groups were comprised in LDPE due to radiation treatment. It was also confirmed that the formation of polar groups on LDPE caused the increased dielectric properties such as permittivity and tan $\delta$. However, in this study, any evidence of decreasing permittivity was not found although the morphological change of LDPE could be identified from the increasing gel content and the decreasing elongation.

• 센서학회지
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• 제23권4호
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• pp.245-250
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• 2014

When the charged particle travels in transparent medium with a velocity greater than that of light in the same medium, the electromagnetic field close to the particle polarizes the medium along its path, and then the electrons in the atoms follow the waveform of the pulse which is called as Cerenkov light or radiation. This type of radiation can be easily observed in a spent fuel storage pit. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, simulated spent fuel assembly and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the intensities of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, we measured the longitudinal distribution of gamma rays emitted from the Ir-192 isotope by using the fiber-optic Cerenkov radiation sensor system and simulated spent fuel assembly.

• 한국축산식품학회지
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• 제31권6호
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• pp.858-864
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• 2011

The effect of adding 10% fat substitute (10%F) or 2% plum extract (2%P) on the formation of hydrocarbons and 2-alkyl-cyclobutanones (2-ACBs) in freeze-dried beef patties, irradiated (IR) at 44 kGy, and freeze-dried irradiated cooked beef patties was investigated. Hydrocarbons, such as $C_{16:3}$, $C_{16:2}$, $C_{17:2}$ and $C_{17:1}$, were detected only in irradiated samples and their concentrations were high in the order of 2%P+IR, IR and 10%F+IR. Only irradiated beef samples produced 2-ACBs (2-DCB, 2-TCB, 2-TeCB), and their amounts were high in reverse order. The addition of fat substitute or plum extract did not help in reducing hydrocarbons and 2-ACBs in the freeze-dried irradiated cooked beef. However, the amounts of radiation-induced hydrocarbons and 2-ACBs in all irradiated beef patties even at 44 kGy were too small to be of concern for human consumption.

• Radiation Oncology Journal
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• 제7권2호
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• pp.299-303
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• 1989

Authors have developed highly reproducible calibration method for the Micro-Selectron HDR Ir-192 system (Nucletron, Motherland). The new jig has a 10cm radius circular hole in the $30cm{\times}30cm{\times}0.2cm$ acrylic plate, and 5F flexible bronchial tubes are attached around the hole. The source moves along the circle in the tubes and the ionization chamber is placed verticaly at the center of the circular hole (center of the jig). Dose distribution near the center was derived theoretically, and measured with the film dosimetry system. Theoretical calculation and measurement show the error margin below $0.1\%$ for 1mm or 2mm position deviation. We have measured at 12 and 24 points of circle with 1, 6, 11 and 21 second dwell time of source in order to calculate the activity of the source. Measurements have been repeated daily for 50 days. The accuracy and the reproducibility are below $1\%$ error margin. The half life of the source from our measurement is estimated $73.4\pm0.4$ days.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1549_1550
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• 2009

본 연구에서는 적외선 가스 센서용 IR source에 대한 연구를 진행하였다. MEMS 공정을 이용하여 poly-silicon을 IR source의 발열체로 사용하였다. Chip size는 $2{\times}2mm$ 이며 membrane의 면적은 $1{\times}1mm$로 설계, 제작 하였다. 제작된 IR source의 적외선 방출 특성을 적외선 카메라를 이용하여 관찰하였으며, 같은 온도에서의 thermal stress에 대한 관찰도 진행하였다.

• 대한방사선기술학회지:방사선기술과학
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• 제44권6호
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• pp.629-633
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• 2021

This article is designed to look into the radiation exposure dose to each body part and the shielding effect for workers using an additional shielding to reduce their radiation exposured by scattering radiation which is generated in a space between the operating table and lead curtain during interventional radiology(IR) procedures. After placing a human phantom on the table of SIEMENS' angiography machine, the following measurements were taken, depending on the presence of an additional shield of lead equivalent of 0.25 mmPb, manufactured for this purpose: dose to gonad, dose to an area where the personal dosimeter is placed, and dose to an area of eye lens is located. An ion chamber(chamber volume 1,800 cc) was utilized to measure scattering radiation. The two imaging tests were carried out as follows: fluoroscopy of the abdomen (66 kV, 100 mA, 60 seconds) and of the head (70 kV, 65 mA, 60 seconds); and digital subtraction angiography(DSA) of the abdomen (67 kV, 264 mA, 20 seconds) and of the head (79 kV, 300 mA, 20 seconds). In all the experiments, the shielding efficiency of the gonad position was the largest at 59.8%. In case an additional shielding was used as protection against scattering radiation that came through the operating table and the lead curtain during an IR, the radiation shielding efficiency was estimated to be up to 59.8%, leading to a conclusion that its presence may effectively reduce the radiation exposure dose of medical staffs.

• 한국방사선학회논문지
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• 제14권1호
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• pp.7-14
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• 2020

본 연구의 목적은 3차원 입체조형 방사선 치료 계획에 고밀도 인공 물체를 삽입하는 불확실성을 보정하기 위해 반복적 재구성(IR)의 유용성을 평가하는 것이다. 쇠구슬 팬텀과 티타늄이 삽입된 대상자의 CT Simulation 영상에서 IR을 적용한 영상과 IR을 적용하지 않은 영상을 얻었으며 선량 평가 인자인 HI, MU와 체적 평가 인자인 Volume과 PCI를 비교하였다. 쇠구슬과 티타늄 팬텀 실험 결과 IR을 적용할 때 고밀도 인공물질의 부피가 각각 4.850%, 11.456% 줄었으며 MU는 0.924%, 1.181% 감소하였다. HI는 0.106%, 0.272% 감소하였고 PCI는 0.358%, 0.867% 감소하였다. IR을 척추 성형술, 대퇴부 정렬핀, 손목 정렬핀 등 대상자의 CT 영상에 적용했을 때 인공물의 부피는 47.76%, 23.841%, 49.339% 감소하였다. MU도 0.924%, 0.294%, 1.675%, HI는 1.232%, 0.412%, 1.695% 감소하였으며 PCI는 4.022%, 0.512%, 13.472% 감소하였다. 결론적으로 3차원 입체조형 방사선 치료 계획시 IR을 적용했을 때 고밀도 인공물이 삽입된 팬텀과 대상자 케이스에서 선량과 체적이 모두 감소되었다는 것을 확인할 수 있었다.