• 대한치과보철학회지
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• 제39권4호
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• pp.410-416
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• 2001

Objective: Disc displacement may affect the joint space narrowing between condylar head and glenoid fossa. This study was designed to evaluate the correlation between the joint space change and the severity of anterior disc displacement. Materials and Methods: Two hundreds temporomandibular joints MR images of TMD patients(170 joints) and asymptomatic volunteers(30 joints) were evaluated for this purpose. Anterior disc displacement was divided into 3 stages(normal, little to mild, and moderate to severe displacement) based on sagittal images, then joint spaces were measured at medial, central and lateral parts of condyle head on coronal MR images, respectively The joint spaces of 3 groups divided according to the severity of anterior disc displacement were compared. Results: The reduction of joint space was related to the severity of the anterior disc displacement at lateral, medial side and especially at center Conclusion: The temporomandibular joint space was affected by the severity of the anterior disc displacement.

• Applied Biological Chemistry
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• 제32권2호
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• pp.143-147
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• 1989

McIntosh apple을 climacteric maximum 시기인 9월 25일에 채취하여 향기성분을 추출, 분리 및 동정한 결과 head space법에 의한 향기성분은 etsers 13종, alcohols 6종, aldehyde 및 ketone 각 1종으로 총 21종을 동정하였다. 연속수증기증류법에 의해 동정된 향기성분은 esters 20종, alcohols 14종, aldehydes 2종 및 ketone 1종으로 총 37종을 동정하여 head space법보다 16종을 더 동정할 수 있었다. 두 방법에 의해 동정된 향기성분 중 모두 ester가 가장 많아 사과에서 가장 중요한 향기성분이었으며 다음이 alcohol이었다.

• 분석과학
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• 제8권4호
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• pp.739-744
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• 1995

The two main methods to prepare water samples for analyzing volatile organic compounds(VOC's) were investigated. One is the purge and trap(PT) method and another is the head space(HS) sampling method. Both methods were effective to transfer the low boiling point components from the water sample onto the capillary column. The cryo-focusing at the top of the main capillary column was an effective way to obtain the sharpness of the chromatographic peaks but could be avoided when a semi-wide bore column was used. The recovery from the same amount of the sample was better in PT than in HS but a larger sample volume in HS method could compensate the lower efficiency. Therefore PT is suitable to the analysis of drinking water where the very low concentration must be determined. HS is suitable to waste water analysis because of the easiness of the operation. The repeatability was good and similar in both methods. For the contamination of the former sample, both methods were tough and could be used without any problems. The matrix effect which could change the equilibrium parameters in HS method was find negligible in many components. The actual samples such as tap water and river water were analyzed with both methods concerning 16 components regulated in Korea.

• 한국게임학회 논문지
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• 제17권4호
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• pp.55-62
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• 2017

본 연구에서는 HMD(Head Mounted Display)를 가지고 Walk-through의 이동시뮬레이션에 대한 평가를 실시하였다. 구체적으로는 VR공간 주변에 배치된 오브젝트 밀집정도(밀도)의 변화가 심리적 이동거리, 이동속도, 이동시간에 어떠한 영향을 미치는지 알아보았다. 연구결과 첫째, 실험 조건 (저밀도, 중밀도, 고밀도)에 있어 조건간의 차이는 모두 유의미하였다. 둘째, 주변 오브젝트의 밀도가 높아질수록 이동시간, 이동속도, 이동거리가 기본조건과 비교하여 평균점이 높게 나타났다. 셋째, 주변의 오브젝트가 VR공간의 이동시뮬레이션에 있어 시간, 속도, 거리의 감각을 향상 시키는 것을 확인하였다.

• 한국항공우주학회지
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• 제41권5호
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• pp.357-365
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• 2013

본 연구에서는 미사일형상의 몸체(쉘)와 쉘의 헤드부에 조종면을 부착한 발사체에서 힘과 모멘트를 측정하였다. 쉘과 헤드부는 상호 분리되어 있으며, 쉘은 모터에 의하여 회전되도록 하였다. 헤드부는 쉘의 회전방향과는 반대로 회전하며, 헤드부의 회전은 한 쌍의 조종면에 동일한 회전 방향으로 각변위을 주어서 비행하는 경우에 자연적으로 회전력이 발생되도록 하였다. 실험에서의 유속은 40 m/s로 설정하였으며, 레이놀드수는 헤드직경을 기준으로 $1.3{\times}10^5$였다. 발사체의 자세제어 및 방향전환을 위하여 헤드부에 있는 다른 한쌍의 조종면은 각변위의 조정이 가능하도록 하였다. 회전하는 발사체에서 힘과 모멘트의 변화가 측정되었으며, 측정된 결과로부터 FFT 분석을 통하여 영향력이 있는 진폭과 주파수를 얻었다.

• International Journal of Internet, Broadcasting and Communication
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• 제9권3호
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• pp.70-77
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• 2017

Dynamic visual acuity is used as an important factor to measure athletic performance in sports field. A study on visual acuity testing system using non-see head mounted display (NST-HMD) was conducted recently. However, the NST-HMD has a problem that the sense of space felt by the subject differs from the actual environment. This is because the view is blocked so that it is only implemented in a virtual space. This paper proposes a dynamic visual acuity testing system using optical see through head mounted display (OST-HMD). To do this, OST-HMD and NST-HMD comparative tests were conducted using existing K-D (King-Devick) charts. Experiments were performed on 30 subjects and their visual acuity was measured and analyzed by parametric statistics and one-sample T-test. The results of the study demonstrate the effectiveness of the proposed OST-HMD. This study is expected to use the visual inspection and training equipment of OST-HMD.

• 대한전자공학회논문지
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• 제27권3호
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• pp.131-136
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• 1990

본 논문에서 게이트레벨 회로의 논리 최적화를 위한 논리적 redundancy조사를 가속화하는 새로운 방법을 제안한다. 게이트레벨 회로의 redundancy 조사문제는 테스트패턴 생성문제와 마찬가지로 유한상태 탐색문제로서, 그 실행시간이 탐색의 크기에 의존한다. 본 논문에서는 효율적인 탐색을 위해, '동적 head line'과 'mandatory 할당' 방법을 제안한다. 동적 head line은 redundancy조사과정에서 동적으로 변경되어, 탐색에서의 backtracking 수를 감소기키며, mandatory 할당은 불필요한 할당을 피할 수 있어 탐색의 크기를 줄인다. 특히 이들 방법은 기존의 테스트패턴 생성문제에서 사용한 방법과는 달리, 회로 최적화에 따른 회로의 변경에 영향을 받지 않고 사용된다. 또한, 이들 방법을 기존의 redundancy 조사시스템에 실현하여, 그 유효성을 보인다.

• 대한기관식도과학회지
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• 제18권2호
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• pp.60-63
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• 2012

Second branchial cleft cysts are usually present as a fluctuant neck mass along the anterior border of the sternocleidomastoid muscle. When they are found in this typical location, accurate diagnosis on initial presentation is not difficult. Parapharyngeal presence of the branchial cleft cyst is very rare. We report a case of second branchial cleft cyst presenting as a parapharyngeal cystic mass in 51-year-old male. Before coming to our clinic, the patient had been diagnosed as parapharyngeal abscess, resulting in several attempts at removal. However, symptoms and parapharyngeal abscess recurred. We performed complete surgical resection of the parapharyngeal cystic mass via transoral approach only with oropharyngeal incision. The cystic mass was located in the parapharyngeal space and did not have tract-like structure. Histopathologic examination confirmed that the excised cyst was branchial cleft cyst. Patient discharged without any surgical complication and there was no evidence of recurrence for 2 years follow-up.

• 대한두경부종양학회지
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• 제5권1호
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• pp.15-20
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• 1989

There is a difficulty in complete removal of tumor developing at the parapharyngeal space or infratemporal space where they are just under the skull base. We have experienced 3 cases of malignant tumors and 5 cases of benign tumors arising from the parapharyngeal spaces and/or infratemporal space since 1976. We hereby present 8 cases of primary tumors arising in these spaces with a review of anatomical relationship between above spaces, the characteristic symptoms, diagnostic technics, and surgical approaches which should be considered in their management.

• 대한두경부종양학회지
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• 제16권1호
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• pp.69-72
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• 2000

The neurilemmoma is a relatively uncommon benign neoplasm which is known to be originated from the schwann sheath of the nerve fiber. Parapharyngeal neurilemmomas may originate from any nerve traversing this space, but the vast majority arise from the vagus nerve and sympathetic chain. The neurilemmomas arising from the extracranial portion of the hypoglossal nerve are extremely rare. To our knowledge, the case we present is the ninth one to be reported occurring in the parapharyngeal space. Recently we experienced a case of parapharyngeal neurilemmoma arising from the hypoglossal nerve and so we report our case with a brief review of literatures.