• The Optical Journal
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• s.139
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• pp.20-25
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• 2012

국내 디지털카메라 시장에 '미러리스 태풍'이 불고 있다. 보급형 디지털카메라 시장을 이끌었던 콤팩트 카메라를 밀어내고 디지털 일안반사식(DSLR)기능에 휴대성을 높인 '하이브리드형' 미러리스(무반사경) 카메라가 시장의 대세로 떠올랐다. 최근 신제품 경쟁도 가열되고 있다. 점점 고기능화 다양화 되는 콤팩트 디카와 DSLR 카메라까지, 디지털 카메라 시장의 각축전이 어느 때보다 치열하다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1194-1202
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• 2002

A study on the topology optimization of a multi-spectral camera for space-use is presented. The optimization is carried out under self-weight and polishing pressure loading. A multi-spectral camera for space-use experiences degradation of optical image in the space, which can not be detected on the optical test bench on the earth. An optical surface deformation of a primary mirror, which is a principal component of the camera system, is an important factor affecting the optical performance of the whole camera system. In this study, topology optimization of the primary mirror of the camera is presented. As an objective function, a measure of Strehl ratio is used. Total mass of the primary mirror is given as a constraint to the optimization problem. The sensitivities of the objective function and constraint are calculated by direct differentiation method. Optimization procedure is carried out by an optimality criteria method. For the light-weight primary mirror design, a three dimensional model is treated. As a preliminary example, topology optimization considering a self-weight loading is treated. In the second example, the polishing pressure is also included as a loading in the topology optimization of the mirror. Results of the optimized design topology for the mirror with various mass constraints are presented.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.186-190
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• 1998

We fabricated a diode-side pumped high power Nd:YAG laser with a gold coated flow tube(diameter of 10mm) and three sets of 140W diode bar. The diameter of Nd:YAG rod was 6mm and its length was 130mm. We obtained 130W cw power from a linear resonator with an 11% output coupler, which corresponds to the slope efficiency of 43% and the optical efficiency of 31%. The measured beam quality factor(M$^2$) reached about 85 which is fairly large due to the large size of the rod. Thermal lensing of the rod was measured to be 5.3-7.4D/$kW_{pump}$ when the laser was operating.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.920-925
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• 2001

A study on the topology optimization of a multi-spectral camera for space-use is presented. A multi-spectral camera for space-use experiences degradation of optical image in the space, which can not be detected on the optical test bench on the earth. An optical surface deformation of a primary mirror, which is a principal component of the camera system, under the self-weight loading is an important factor affecting the optical performance of the whole camera system. In this study, topology optimization of the primary mirror of the camera is presented. Total mass of the primary mirror is given as a constraint to the optimization problem. The sensitivities of the objective function and constraint are calculated by direct differentiation method. Optimization procedure is carried out by an optimality criterion method using the sensitivities of the objective function and the constraint. As a preliminary example, topology optimization considering a self-weight loading is treated. For practical use, the polishing pressure is included as a loading in the topology optimization of the primary mirror. Results of the optimized design topology for the primary mirror with varying mass ratios are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.11
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• pp.1161-1169
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• 2003

In this paper, ADE(Axially Displaced Ellipse) Gregorian dual reflector antennas, which are the special form of Gregorian dual reflector antennas, were analyzed. In the procedure of antenna analysis, the aperture field distribution was obtained by using the geometrical optics and their far-field radiation characteristics were analyzed by using the aperture field method. The analysis results such as antenna efficiency, HPBW(Half Power Beam Width), FNBW(First Null Beam Width), and FSL(First Sidelobe Level) were presented as functions of edge taper and size of main reflector and subreflector. From the results in this paper, we could confirm that ADE reflector antennas have the different radiation characteristics from the classical dual reflector antennas.

• The Korean Journal of Pain
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• v.20 no.2
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• pp.246-250
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• 2007

We report here on a case of right side spasmodic torticollis (ST) that was refractory to botulinum toxin type A injection and medication. The patient finally underwent a selective ramisectomy with ipsilateral sternocleidomastoid muscle (SCM) resection, but the remaining symptoms slowly aggravated, and a contralateral left side SCM spasm began. As conservative therapy for reducing the spasmodic symptoms, accessory nerve block, upper cervical plexus block and stellate ganglion block were performed twice in a week. After 6 months, the spasmodic symptoms significantly decreased. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) decreased by more than 70%. After one year of serial intermittent local anesthetic blockade therapy, the patient became almost free from the original ST symptoms (TWSTRS = 1). Serial local anesthetic interventions for the ST patient may have a beneficial role on the pathological peripherocentral neural activity of the ST patient and can modulate motor-sensory integration in the patient.

• Journal of Genetic Medicine
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• v.8 no.1
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• pp.71-75
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• 2011

A male infant was diagnosed with obstetric brachial plexus injury, congenital muscular torticollis and cleft palate 17 days after birth. His mother presented with gestational diabetes and premature rupture of membranes. Although it is possible that these three disorders arose independently, it is very likely that all three have the same etiologic cause, and we propose that a possible mechanism for this concurrence is related to maternal gestational diabetes. Maternal hyperglycemia mostly affects fetal structures deriving from the neural crest, including the palatine bone, and may have caused the cleft palate observed in this case. Gestational diabetes is also associated with increased frequency of large for gestational age infants and, by extension, with increased risk of birth injuries such as obstetric brachial plexus injury or congenital muscular torticollis associated with large for gestational age infants. Since the children of mothers with gestational diabetes are at increased risk for congenital defects such as cleft palate as well as being large for gestational age, precautions indicated for each respective disorder must be taken during prenatal testing and during birth. However, further studies of more cases are required to evaluate whether the concurrence of obstetric brachial plexus injury, congenital muscular torticollis and cleft palate in this case are complications specifically associated with gestational diabetes or just a simple coincidence.

• Korean Journal of Environmental Agriculture
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• v.9 no.1
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• pp.53-59
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• 1990

Root zone environments in hydroponics are very important factors in crop growth, development and quality. In Korea, improvement of root zone temperature is required because of the continental climate. Therefore, this investigation was carried out to clarify the difference of root zone environments in different hydroponic systems under different climates. Tomato plants were grown in nutrient solutions at Seoul City University and Allen Cooper's. Hydroponic systems in this experiment were aeroponics, nutrient film technique(NFT), rockwool culture, sand culture and smoked rice hull culture(SRH). The decrease in temperature rapidly occured in sand culture while slowly in rockwool culture in low air temperature periods. The internal temperature of substrates of hydroponic bed were slightly changed in rockwool culture under high air temperature periods, while the duration of high temperature was longest in NFT. Electrical conductivity and pH of nutrient solution showed great changes in rockwool and aeroponics. Along the bed, the content of dissolved oxygen in nutrient solution had a tendency to decrease in NFT and DFT(Deep flow technique), while didn`t a change with aeroponics. Root activity measured by triphenyl tetrazolium chloride (TTC) was highest with aeroponics, followed by rockwool culture and NFT.

• Journal of Veterinary Clinics
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• v.23 no.3
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• pp.340-343
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• 2006

A 10-year-old, intact female Beagle dog was presented for examination of acute onset of right-sided head tilt and moderate ataxia. Clinical signs were acutely presented 12 days ago and had been progressively alleviated until the admission day. The dog was bright, alert, and responsive. On neurological examinations, mild head tilt to the right and mild ataxia were noted, thus vestibular disorders were suspected. Central vestibular disease was ruled out based on the clinical signs, magnetic resonance imaging(MRI), and cerebrospinal fluid(CSF) analysis. Otoscopic examination showed that the tympanic membranes were intact and normal in appearance. On radiographic and MR examinations, abnormalities were not found in the tympanic bulla and the petrous portion of the temporal bone. Hypothyroidism was ruled out by thyroid-stimulation hormone(TSH) stimulation test. Clinical signs were completely disappeared at 2 weeks after discharge without any therapy. Thus, the dog was definitively diagnosed as idiopathic vestibular disease based on the clinical signs, excluding other causes of vestibular dysfunction, and the alleviation of clinical signs with time.

• Review of KIISC
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• v.26 no.6
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• pp.51-57
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• 2016

IT 기술의 발달로 다양한 인터넷 서비스를 사용하게 되면서 개인정보의 유출 등 위협이 증가하고 있다. 이에 개인정보의 중요도가 높아지면서 정보보안에 대한 관심도 높아지고 있다. 현재까지 많이 사용되고 있는 인증기술들은 단일 요소 인증으로 다중 인증(multi-factor authentication) 기술에 비하면 취약하다. 본 논문에서는 행위기반 바이오 인증 기술들 중 다중 인증을 하는데 이용 가능한 기술들에 대해 분석하고, 특성을 제시한다.