• 제목/요약/키워드: Cornea

검색결과 278건 처리시간 0.023초

사용자 캘리브레이션이 필요 없는 시선 추적 모델 연구 (User-Calibration Free Gaze Tracking System Model)

  • 고은지;김명준
    • 한국정보통신학회논문지
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    • 제18권5호
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    • pp.1096-1102
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    • 2014
  • 적외선 조명을 이용한 간접시선추적 시스템에서는 촬영된 이미지에서 동공에 반사된 조명의 위치에 대한 캘리브레이션이 필수적이다. 하지만 안구의 크기나 머리의 위치에 따라 달라질 수도 있는 변수가 캘리브레이션 과정에서 정의된 상수로 계산에 포함되어 있어 오차를 감소시키는데 한계가 있다. 본 논문은 적외선 조명을 사용하면서도, 사용자 캘리브레이션 과정을 생략할 수 있는 방법을 연구한다. 반사각에 의한 글린트(glint)위치 차이에 영향을 받지 않게 하면서, 시스템의 모델과 시선 계산은 단순하게 하여 실시간 연산이 가능하도록 하는 것이 목표이다.

전두엽 뇌전도 전극 배치의 제안 및 JADE를 이용한 잡음제거 (Proposition of the EEG Electrode Arrangement at a Frontal Lobe and Rejection of Noise Using a JADE)

  • 박정제;이윤정;김필운;구성모;조진호;김명남
    • 대한의용생체공학회:의공학회지
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    • 제25권3호
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    • pp.227-233
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    • 2004
  • 본 논문에서는 뇌전도 바이오피드백 시스템을 위한 4채널 전두엽 전극 배치 및 JADE를 사용한 잡음 제거 방법을 제안하였다. 망막-각막 쌍극자 모델을 기반하여 4채널 전두엽 전극 배치를 제안하였으며, 이 배치에 의해서 얻은 신호에 대해서 JADE를 적용하여 4개의 독립 성분을 획득하였다. 각 독립 성분들 중에서 순수 뇌전도 성분을 추정하기 위해서 전체 신호에 대한 알파파비를 측정하여 그 값이 가장 큰 독립 성분을 잡음이 제거된 순수한 뇌전도로 추정하였다. 그 실험 결과 제안한 방법이 뇌전도 획득 과정에서 효과적으로 잡음을 제거함을 확인하였다.

개에서의 Tiletamine-Zolazepam 마취의 임상경험 (Clinical Use of Tiletamine-Zolazepam Anesthesia in Dogs)

  • 남치주;서강문;윤정희
    • 한국임상수의학회지
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    • 제10권2호
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    • pp.215-220
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    • 1993
  • The anesthetic effects by dosages of Tiletamlne-Zolazepam in the dogs were investigated and then the optimal dosages for the operation of patients were suggested. 1. In groups of T+Z 20, 10 and 5 mg/kg administration, anesthetic periods are 180~300, 33~47 and 40~50 minutes, respectively and complete recovery from anesthesia was shorted with taking 53~72 minutes in the group of 5 mg/kg administration. 2. Reflex responses to eyelids, cornea and pharyngolarynx were maintained but pedal reflexes became considerably sluggish 3. It showed tachycardias on ECG but there were no specific dysrhythmias. On EEG, it showed low voltage-fast waves before anesthesia, high voltage-fast waves in induction stage, low voltage-slow waves in anesthetic stage and high voltage-fast waves again in recovery stage. 4. Surgical procedures could be performed satisfactorily in 6 cases of the 10 mg/kg administration group, but in 3 of 5 cases of 5 mg/kg administration group it could be completed after additional administration. 5. In conclusion, it was considered desirable for anesthetizing dogs that for healthy cases T+Z at the level of 10 mg/kg B.W. was administered, and for poor risk patients, 5 mg/kg B.W., followed by an additional administration in unsatisfied cases.

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6 MV 광자선치료에서 안구차폐기구의 제작과 선량분포 측정 (Dose Distribution for Eye Shielding Block In 6 MV Photon Beam Therapy)

  • 이경자
    • Radiation Oncology Journal
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    • 제10권2호
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    • pp.155-161
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    • 1992
  • 눈의 수정체는 방사선에 매우 예민한 장기이며 비교적 적은 선량에서도 백내장의 원인이 될 수 있다. 그러므로 두경부암의 방사선치료에서 수정체를 최대한 차폐하면서 병소에 집중 조사하는 방법이 개발되어야 한다. 저자는 안구의 표면에서 0.5 cm 깊이에 위치하며 폭 1 cm인 눈의 수정체를 최대한 차폐하면서 주위 병소를 치료하기 위하여 원자번호가 높은 차폐물질을 이용하였으며 최적조사조건은 측정실험을 통하여 결정하였고 이를 임상치료에 응용하였다. 수정체의 차폐기구는 제작하기 쉽고 차폐효과가 큰 혼합금속(Cerrobend)이 적당하였으며 두께 7.5 cm와 직경 1 cm의 원뿔기둥모양이 가장 이상적이었다. 차폐기둥의 밑면과 표면과의 거리가 l0 cm일 때 수정체에 가장 적은 선량이 부여되며 병소에는 비교적 많은 선량이 부여된다. 이때 각막(Cornea, 1 mm), 수정체 (Eye Lens, 5 mm), 망막(Retina, 25 mm) 및 병소(Tumor, 50 mm 이상)의 선량은 차폐물이 없을 때와 비교하여 각각 $10.0\%$, $15.2\%$, $21.5\%$$23.2\%$로 측정되었다.

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편측성 만성 녹내장을 지닌 Shih-tzu의 안구적출술 치유예 (A Case of Transpalpebral Enucleation in Shih-tzu with Chronic Unilateral Glaucoma)

  • 정순욱;정월순
    • 한국임상수의학회지
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    • 제16권1호
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    • pp.203-209
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    • 1999
  • A 4-year-old female Shih-tzu with severe episcleral congestion and buphthalmos in left eye was referred to the Veterinary Teaching Hospital, Chonnam National University in October 1998. During two months in local veterinary clinics, the dog had been treated unsuccessfully with tarsorrhaphy and antibiotics. By history taking, cause of the glaucoma was ascertained as accidental nonpenetrated cornea trauma by owner, Ophthalmic examination revealed that the left eye was buphthalmic with severe episcleral congestion, pain and fever. The direct pupillary light response could not be evaluated in the left eye, but right eye had normal reaction. The intraocular pressure was 4.5 mmHg in the right eye and 33 mmHg in the left eye, as measured with a Schiotz tonometer, Ultrasonographic finding revealed hyperechoic vitrous body and central echofree material. The Schirmer tear test showed 20 mm in the left eye and 8 mm in the right eye. The hematologic examination revealed monocytosis. The initial medical treatment was admitted, but there was no response. Transpalpebral enucleation in the left eye under inhalation anesthesia with enflurane 1.2 vol% in oxygen was performed. The day after operation the left eye ravealed no exudate, and pain, and the systemic vital signs were normal. The prognosis is excellent.

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Molecular characterization of Acanthamoeba isolated from amebic keratitis related to orthokeratology lens overnight wear

  • Lee, Jun-Joo;Jeong, Hae-Jin;Lee, Ji-Eun;Lee, Jong-Soo;Xuan, Ying-Hua;Kong, Hyun-Hee;Chung, Dong-Il;Ock, Mee-Sun;Yu, Hak-Sun
    • Parasites, Hosts and Diseases
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    • 제44권4호
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    • pp.313-320
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    • 2006
  • In an effort to characterize, on the molecular scale, the Acanthamoeba initially isolated from the cornea of an amoebic keratitis patient associated with overnight-wear orthokeratology lens in Korea, we conducted mitochondrial DNA restriction fragment length polymorphism, 18S rDNA sequencing, and drug sensitivity analyses on the isolate (KA/PE1). The patient was treated with polyhexamethylene biguanide, chlorhexidine and oral itraconazole, which resulted in resolution of the patient's ocular inflammation. The majority of the molecular characteristics of the KA/PE1 were determined to be identical, or quite similar, to those of A. castellanii Ma strain, which had been isolated also from amoebic keratitis. The risk of Acanthamoeba keratitis as a potential complication of overnight orthokeratology is briefly discussed.

토끼의 각막 추출액 중 메치오닌엔케팔린 및 [D-알라$^2$-메치오닌엔케팔린아미드의 분해 및 안정화 (Degradation and Stabilization of Methionine Enkephalin and $[D-Ala^2]-methionine$ Enkephalinamide in the Corneal Extracts of Rabbits)

  • 이치호;이경진;전인구;성영기;신영희
    • Journal of Pharmaceutical Investigation
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    • 제24권1호
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    • pp.1-9
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    • 1994
  • In order to study systemic peptide delivery through the ocular route, the stabilities of methionine enkephalin (Met-Enk) and $[D-ala^2]-methionine$ enkephalinamide (YAGFM) in the corneal extracts of rabbits were investigated using reversed phase HPLC. Met-Enk was found to be hydrolyzed most rapidly in the corneal epithelium, but YAGFM was relatively stable. Aminopeptidases appeared to contribute over 60% to the degradation of Met-Enk and the degradation rate of Met-Enk followed the first order kinetics. The half-lives of Met-Enk in the extracts of the corneal epithelium and endothelium were 36 and 673 min, respectively. From the effects of enzyme inhibitors, it was found that the application of the mixture of amastatin, thimerosal and EDTA was very useful for the inhibition of peptide degradation.

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Eye Irritation, Skin Irritation and Skin Sensitization tests for Aloewhite in Animals

  • Kim, Hyung-Sik;Kwack, Seung-Jun;Kim, Kyu-Bong;Lee, Seung-Ki;Park, Hyun-Sun;Hong, Che-Young;Ahn, Mi-Young;Jo, Tea-Hyung;Oh, Sun-Tack
    • 한국응용약물학회:학술대회논문집
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    • 한국응용약물학회 1996년도 춘계학술대회
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    • pp.250-250
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    • 1996
  • Eye irritation, primary skin irritation and skin sensitization tests for Aloewhite were tested in New Zealand White rabbits and Hartley guinea pig. In primary skin irritation test of male New Zealand White rabbits, body weights were not significantly changed and primary Irritation Index(PII) was 0.47, indicating Aloewhite as mildly irritating material, In ocular irritation test, any injury on iris, conjunctival membrane, and cornea in New Zealand White rabbits was not observed. No injuries of the ocular mucous membrane were also recorded. Skin sensitization was tested in guinea Peg after intradermal and epicutaneous induction and graded I with zero % sensitization rate. These results indicate that Aloewhite was not considered to be irritant in test organs of animals.

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The Use of Lens Shielding Device(L.S.D.) for a Conjunctival Lymphoma

  • 조현상;주상규;송기원;박영환
    • 대한방사선치료학회지
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    • 제9권1호
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    • pp.40-45
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    • 1997
  • When therapeutic irradiation is indicated for the orbital tumors, the greatest concern is the risk of radiation-induced cataract. Conjunctival lymphoma is one of the good examples. We would like to report the procedure of the lens shielding device(L.S.D) and the result of irradiated dose to the lens. L.S.D. consistes of two parts : load alloy to attenuate electron beam, and dental acryl which completely covers the lead alloy to avoid discomfort of cornea from contacting directly with cerrobend and side scattering by cerrobend. And for easy location and removal, side bars were made on each side. Radiation doses were meaured with TLD(TLD 3500 Hawshaw). Markus chamber in a polystyrene phantom. The phantom was irradiated with 9MeV electron beams from Clinac 2100C with $6{\times}6cm$ electron cone. The relative dose at 6mm depth where the lens is located was $4.2\%$ with TLD and $5.1\%$ with Markus chamber clinically when 2600 cGy are irradiated to the eyeball, the mapinary dose to the lens will be 109 cGy or 132 cGy, which will significently reduce the cataract.

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Rotation Matrix를 이용한 안구운동의 수학적 표현 (Mathematical Expression of Eye Movement Using Rotation Matrix)

  • 김용근
    • 한국안광학회지
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    • 제4권2호
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    • pp.51-55
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    • 1999
  • 안구운동의 회선점을 중심으로 한 안구운동은 직각좌표의 좌표축 회전변환에 의한 회전행렬 $R_x$, $R_y$, $R_z$로 표현할 수 있으며, 6가지의 눈의 주된 회전 형태인 외-내전, 상-하전, 내-외방 회선 등으로 기술된다. 제1안위에서 제3안위까지의 안구운동은 회전행렬의 조합으로 구성되고, 6가지의 주회전과 8가지의 보조회전으로 6개의 외안근 운동을 표현 할 수 있다. 안구운동에 의한 동공점인 각막정점의 위치를 각각좌표의 회전행렬을 구좌표$(r,{\theta},{\phi})$로 전환하여 9가지로 기술된다.

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