• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.2
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• pp.142-152
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• 1992

This paper presentes a new method to measure high electric field (or high voltage) by using crystalline SiO2 which has very high half wave voltage. There are many difficulties in measuring high electric field using other crystals which have generally low half wave voltage.By applying Stokes parameter and Mueller matrix. We derive optical modulation equation in the sensor which is composed of a polarizer, and Mueller matrix, we derive optical modulation equation in the sensor which is composed of a polarizer, a Pokels material, and an analyzer, We theoretically analyzed electro-optic effect, and calculated the phase retardation and half wave volt age of the birefringent material. The designed optical valtage sensor has very excellent linearity up to 20KV without divided volt-age. The maximum error was measured within 3%. Before annealing of Sio2 crystal, the maximum variation of the output voltage is 7.5% with varying temperature from \ulcorner20˚c to 60˚c. But, after annealing of SiO2 crystal, the output voltage variation is improved within 1%error.

• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.57-64
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• 2021

In the study, to minimize the error on guided control of the KV (Kill Vehicle) and to secure the hit-to-kill performance, a position accuracy inspection for the DACS (Divert and Attitude Control System) actuation system was proposed. The accuracy performance of the DACS actuation system is one of the most important factors in the interception of ballistic missiles. In order to validate actuation control accuracy of DACS system, an inspection item was set for position accuracy, and the inspection system was designed for DACS pintle. To measure the absolute position value of the DACS pintle, an external measurement system was developed using laser displacement sensors. The inspection system was designed so that it can be compared with the actuation command in real time. The proposed position accuracy inspection system can be inspected not only in a DACS system but also in missile system level. The position accuracy inspection was performed using the designed inspection system, and analysis of the inspection result.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.1-7
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• 1998

Due to the increase in capacity of auxiliary machinery in power plant, the importance of energy saving has been greatly emphasized. If the speed of fans or pumps is controlled in accordance with the variation of load, large electric energy can be saved. Large capacity inverter, 2MVA GTO inverter, has been developed by operating two of 1MVA unit inverters in parallel. The parallel operation of the unit inverter is accomplished through two output transformers of which the secondary windings are connected in series. The system is composed of one control cubicle, one rectifier cubicle and 2 unit inverter cubicles. This inverter system was applied to the sea water lift pump(SLP) driven by a 6.6KV 1500KW induction motor in Seo-Inchon power plant to save the electric energy. The parallel operation of inverters by 180 degrees apart in switching frequency helps to reduce the harmonic components.

• Journal of Embryo Transfer
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• v.16 no.3
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• pp.213-221
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• 2001

This study was conducted to examine in vitro developmental ability of porcine embryos after somatic cell nuclear transfer. The porcine ear fell was cultured in vitro for confluency in serum-starvation condition(TCM-199 + 0.5% FBS) far 3~6 days of cell confluency. The zona pellucida of IVM oocytes were partially drilled using laser system. Single somatic cell was individually transferred into enucleated oocytes. And the reconstructed embryos were electrically fused(single DC 1.9kv/cm, 30$\mu$ sec) with 0.3M mannitol. After electrofusion, embryos were activated(single AC 5v/mm, 5sec) and cultured in HCSU-23 medium containing 10% FBS at 39$^{\circ}C$, 5% $CO_2$ in air for 6 to 8 days. The fusion rate of donor cells was 45.6, 36.8 and 46.1% in 3~4, 5~6 days of serum starvation and non serum starvation(N-S), and were 52.7. 53.0 and 51.7% in 1~2. 5~6 and 13~14 passages of donor cell culture, respectively. No significant difference was found in the fusion rate of donor cells by the duration of serum starvation treatment or the number of donor cell passages. By the size of donor cells, however, the fusion rate was significantly higher(P<0.05) for reconstructed embryos derived from 25r $\mu$m $\geq$ site of donor cells (65.3%) than that of 25~30$\mu$ m(42.5%) or 30$\mu$ m(45.5%)$\leq$ cells. The cleavage rate was significantly (P<0.05) higher in 3~4 darts of serum starvation treatment(67.1%) than that in N-S (50.7%) or 5~6 days of starvation(57.1%). The activation rate by the size of donor cells in fused oocytes was 56.5, 68.8 and 58.5%, respectively, and was not significant.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.1
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• pp.33-39
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• 2009

Purpose: The aim of this study is to compare patient's body posture and its position at the time of simulation with one at the treatment room using On-board Imaging (OBI) and CT (CBCT). The detected offsets are compared with position errors of Rando Phantom that are practically applied. After that, Rando Phantom's position is selected by moving couch based on detected deviations. In addition, the errors between real measured values of Rando Phantom position and theoretical ones is compared. And we will evaluate target position's accuracy of KV X-ray imaging's 2D and CBCT's 3D one. Materials and Methods: Using the Rando Phantom (Alderson Research Laboratories Inc. Stanford. CT, USA) which simulated human body's internal structure, we will set up Rando Phantom on the treatment couch after implementing simulation and RTP according to the same ways as the real radioactive treatment. We tested Rando Phantom that are assumed to have accurate position with different 3 methods. We measured setup errors on the axis of X, Y and Z, and got mean standard deviation errors by repeating tests 10 times on each tests. Results: The difference between mean detection error and standard deviation are as follows; lateral 0.4+/-0.3 mm, longitudinal 0.6+/-0.5 mm, vertical 0.4+/-0.2 mm which all within 0~10 mm. The couch shift variable after positioning that are comparable to residual errors are 0.3+/-0.1, 0.5+/-0.1, and 0.3+/-0.1 mm. The mean detection errors by longitudinal shift between 20~40 mm are 0.4+/-0.3 in lateral, 0.6+/-0.5 in longitudinal, 0.5+/-0.3 in vertical direction. The detection errors are all within range of 0.3~0.5 mm. Residual errors are within 0.2~0.5 mm. Each values are mean values based on 3 tests. Conclusion: Phantom is based on treatment couch shift and error within the average 5mm can be gained by the diminution detected by image registration based on OBI and CBCT. Therefore, the selection of target position which depends on OBI and CBCT could be considered as useful.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.48-51
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• 1997

(Pb. La)TiO$_3$ thin films were fabricated by sol-gel Processing and spin-coated on the Pt substrate. The spin-coated PLT films were sintered at 75$0^{\circ}C$ for 5min by rapid thermal ann La content dependence of the electrical properties of the PLT thin films are discussed. Wit La mole% from 20 to 36mo1e%. the dielectric constant of the PLT thin films decreased f 570. P-E hysteresis loops changed from ferroelectric to paraelectric. and the charge storage charging time decreased. The Curie Point decreased with increasing La content. The leak density also decreased and La 36mo1% species shows mood characteristics less than 10- electric field 500 (KV/cm) Because of the broad range of composition-controlled ferroelectric PLT thin films are suitable for memory application.

• Journal of radiological science and technology
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• v.4 no.1
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• pp.31-36
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• 1981

We studied radiation dose in mammography through 34-46 kv range using acryl phantom. The obtained results were as follows: 1. Incident radiation was maximum with high kvp and thin added filtration. 2. Transmitted radiation by acryl phantom and its thickness were in reciprocal relationship. 3. The acryl thickness to produce comparable film density with soft tissue of breast was 6 cm. 4. The X-ray exposure for comparable density radiographs increased mammographic film more than medical x-ray film and the amount of x-ray exposure was directly proportional to the added filtration of x-ray beam. 5. The surface dose of x-ray exposure needed to produce film density of 1.0 for 6cm acryl phantom was 1,084-1,575mR in mammographic film and 476-625 mR in medical x-ray film.

• Journal of Biomedical Engineering Research
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• v.15 no.1
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• pp.1-8
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• 1994

Electrofusion of cabbage protoplasts was performed with a developed equipment which consists of a parallel wire electrode, a AC field generator, and a pulse generator. Exposure of protoplasts to an alternating current field of 450 KHz causes attraction to each other which leads to chains of protoplasts extending from the electrode. Intra-specific protoplast fusion was effectively induced within the pearl chains by the additional application of a single high-intensity DC square wave pulse of 1 KV/cm for 1-3 msec. To improve the performance, micro fusion electrode fabricated from the semiconductor technology and microcontroller based field an, d pulse generator was proposed. The viability of protoplasts after an application of electric field at optimum condition was reduced by only 5 % compared with that of pre-application. A prototype of fusion electrode, which consists of insulator-structure, was successfully fabricated by using photosensitive polyimide.

• JOURNAL OF ELECTRICAL WORLD
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• s.255
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• pp.76-83
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• 1998

대용량 파워일렉트로닉스기기의 보다 대용량화$\cdot$소형경량화 및 저손실화 요구에 응하기 위하여 조지전압 4.5KV, 가제어전류 4KA의 고내압$\cdot$대용량 CGT(gate commutated turn-off : 게이트 전류형 턴오프) 사이리스터를 개발하여 상품화하였다. GCT사이리스터는 대용량 파워일렉트로닉스기기의 키파트로서 폭넓게 사용되고 있는 GTO(Gate turn-off)사이리스터와 Turn-on동작이 같고 gto사이리스터의 이점이 저On전압특성을 그대로 갖는 한편 턴오프동작은 ''턴오프 게인이 1''인 새로운 원리에 기초하고 있으며 턴오프특성에서는 GTO사이리스터에 비해 다음과 같은 특징을 갖고있다. (1)GTO사이리스터응용에서 턴오프시 dv/dt를 억제하기 위하여 필요한 스나버회로가 없어도 턴오프동작이 가능하다. (2)축적시간을 종래 GTO사이리스터의 약 1/10로 저감할 수 있다. (3)게이트축적전하를 종래의 GTO사이리스터의 약 1/2로 저감할 수 있다. 이러한 턴오프특성에 의하여 GCT사이리스터는 대용량 파워 일렉트로니스기기에 스나버회로 손실발생의 억제에 의한 손실의 저감, 고속동작화, 직병렬접속 응용에 의한 대용량화의 용이성, 게이트구동회로의 용량을 반감하는 등 많은 메리트를 가져다 준다.

• KSBB Journal
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• v.5 no.3
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• pp.299-306
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• 1990

Escherkchla coli/Cownebacterium glutamicum shuttle vectors, pECCGl and pECCG2 were constructed by joining a 3.0 kb C. glutamicum cryptic plasmid pCBl and a 3.94 kb E. coli plasmid pACYC177. Using the plasmid pECCGl, various parameters involved in electroporation system including electric field strength, resistance, DNA concentration, cell concentration and growth stage were investigated independently and optimized for the high efficiency transformation of coryneform bacteria. Transformation efficiencies of 106 transformants/$\mu\textrm{g}$ of plasmid DNA were achieved with Corynebacterium glutamicum.