• 대한치과교정학회지
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• 제18권1호
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• pp.253-265
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• 1988

This study was designed to compare the normal head posture group with the extended head posture group in order to investigate the relatinship between head posture and craniofacial morphology. The subjects were devided into two groups; one included 80 children with normal head posture and occlusion, and the other 60 malocclusion patients with extended head posture. Their lateral cephalograms were traced and analysed based on 38 selected items. The following conclusion were reached. 1. The craniocervical angulations in normal group; OPT to SN, CVT to SN, OPT to FH and CVT to FH angles were $101.7^{\circ},\;104.8^{\circ},\;91.7^{\circ}\;and\;100.7^{\circ}$, respectively. 2. Compared with normal group, experimental group showed increase in mandibular plane angle, decrease in facial plane angle, airway space and posterior facial height but, there were insignificant differences in anterior facial height and tongue level between two groups. 3. Of the craniocervical angulations, OPT to FH angle was most highly correlated to the variables of the craniofacial morphology. 4. The effect of craniocervical angulation on craniofacial morphology in experimental group was different from that in comparison of normal group and experimental group.

• Clinics in Shoulder and Elbow
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• 제22권4호
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• pp.216-219
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• 2019

Background: Progression of the tear size and erosion of the greater tuberosity (femoralization) in the supraspinatus tear makes it difficult to repair or increases the risk of a re-tear. This study examined the proximal articular surface and greater tuberosity of the humeral head in plain radiography. Methods: Two-hundred forty-seven cases, whose anteroposterior (AP) radiographs were taken correctly, were included from 288 cases, in whom the status of the supraspinatus had been confirmed by surgery. After downloading the plain AP radiograph as DICOM, the radius of the circle apposed at the superior half of the articular surface of the head, and the distance between the circle and the farthest point of the greater tuberosity ('height' of the greater tuberosity) were calculated using the software (TechHime, Korea). MRI checked the number of torn tendons and degree of muscular atrophy. Results: The following were encountered: 93 intact supraspinatus, 50 partial-thickness tears, and 104 full-thickness tears. In the analysis using the 93 intact cases, the average radius of the rotation center was 25.3 mm in male and 22.3 mm in female. The average height of the greater tuberosity from the circle with the same rotation center was 4.3 mm in male and 4.2 mm in female with no statistical significance. The correlation between the reparability of supraspinatus and height of the greater tuberosity, fatty infiltration, and muscular atrophy was confirmed. Conclusions: The height of the greater tuberosity from the circle with the same rotation center was 4.3 mm in male and 4.2 mm in female. This height was strongly correlated with muscular atrophy and fatty infiltration of the supraspinatus tendon.

• 한국발생생물학회지:발생과생식
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• 제10권2호
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• pp.93-96
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• 2006

전어, Konosirus punctatus의 부화후부터 부화후 30일까지의 전장, 두장, 두고, 안경, 망막 두께 및 렌즈직경의 성장은 비례직선적이었다. 전장에 대한 두장 및 두고의 상대 성장, 두장에 대한 안경 및 렌즈직경의 상대 성장, 두고에 대한 안경 및 렌즈직경의 상대 성장, 그리고 망막 두께에 대한 안경, 렌즈직경, 두장, 두고의 상대 성장은 높은 상관계수를 보이는 상대성 장식을 보였다. 눈은 부화 후 9일에 완전히 형성되었으며 렌즈, 신경섬유층, 신경세포층, 내망상층, 내과립층, 외망상층, 외과립층, 외한계막, 간체와 추제층 및 상피층으로 구성되었다. 본 연구와 더불어 차후, 전어의 빛 민감성과 공간적 변화에 따른 망막 관련 연구가 필요하리라 사료된다.

• Korean Journal of Radiology
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• 제24권7호
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• pp.681-689
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• 2023

Objective: Three-dimensional rotational angiography (3D-RA) is increasingly used for the evaluation of intracranial aneurysms (IAs); however, radiation exposure to the lens is a concern. We investigated the effect of head off-centering by adjusting table height on the lens dose during 3D-RA and its feasibility in patient examination. Materials and Methods: The effect of head off-centering during 3D-RA on the lens radiation dose at various table heights was investigated using a RANDO head phantom (Alderson Research Labs). We prospectively enrolled 20 patients (58.0 ± 9.4 years) with IAs who were scheduled to undergo bilateral 3D-RA. In all patients' 3D-RA, the lens dose-reduction protocol involving elevation of the examination table was applied to one internal carotid artery, and the conventional protocol was applied to the other. The lens dose was measured using photoluminescent glass dosimeters (GD-352M, AGC Techno Glass Co., LTD), and radiation dose metrics were compared between the two protocols. Image quality was quantitatively analyzed using source images for image noise, signal-to-noise ratio, and contrast-to-noise ratio. Additionally, three reviewers qualitatively assessed the image quality using a five-point Likert scale. Results: The phantom study showed that the lens dose was reduced by an average of 38% per 1 cm increase in table height. In the patient study, the dose-reduction protocol (elevating the table height by an average of 2.3 cm) led to an 83% reduction in the median dose from 4.65 mGy to 0.79 mGy (P < 0.001). There were no significant differences between dose-reduction and conventional protocols in the kerma area product (7.34 vs. 7.40 Gy·cm², P = 0.892), air kerma (75.7 vs. 75.1 mGy, P = 0.872), and image quality. Conclusion: The lens radiation dose was significantly affected by table height adjustment during 3D-RA. Intentional head off-centering by elevation of the table is a simple and effective way to reduce the lens dose in clinical practice.

• 한국의류학회지
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• 제29권5호
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• pp.737-744
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• 2005

This study was aimed to provide the measurement data and shape classification of the head of the Korean male children for the headwear sizing systems. Five hundred twenty male children, aged nine to twelve years, participated f3r this study. The 17 regions on the head and height, weight of the subjects were directly measured by the expert experimenters. Factor analysis, cluster analysis, GLM analysis and Tukey HSD test were performed using these data. Through factor analysis, low factors were extracted upon factor scores and those factors comprised $69.76\%$ for the total variances. Three clusters as their head shape were categorized using four factor scores by cluster analysis. Type 1 was characterized by the widest width and Bitragion arc, shortest head length. Type 2 had the longest head length and the widest side width and the highest head length and head circumference. Type 3 was characterized by the smallest head circumstance, head width and side width, and medium head length.

• 수산해양기술연구
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• 제43권2호
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• pp.87-100
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• 2007

This study was carried out to offer fundamental data for improving the fishing efficiency of the Danish seine. The net height and the shape in the water was measured to analyze the efficiency of the existing Danish seine. And then, an improved fishing gear was developed based on the results and was tested in the field. Measuring devices were attached on center of a ground rope and a head rope. The net height is the spread distance between the ground rope and the head rope, which was measured on the different ratio of buoyancy. The results are obtained as follows. The net height estimated from the design plan of horizontal hanging ratio 0.40 in the existing Danish seine A and B estimated both 4.94m. The net height of the existing Danish seine A and B was respectively 1.8m and 2.3m, which form 36.4% and 46.2% of the net height estimated from the design plan. Buoyancy was changed as 79.5% and 96.2% relative to the sinking force in the existing Danish seine. The net height of 79.5% was 3.95m which increased to 80% of the estimated net height. The other shows the same result with the first case. It is not necessarily that the high buoyancy/sinking force ratio make the high net height, 80% is adequate as the buoyancy/sinking force ratio. In case of the improved Danish seine, the mean net height was about 5.0m, means 58.3% of estimated net height 8.58m.

• 물과 미래
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• 제29권1호
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• pp.213-220
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• 1996

본 연구는 siphon의 수리학적 현상을 이용하여 배수를 제어하는 Cherepnov 송수기의 효율적인 양정(유입수조의 수면과 송수관 출구의 위치차)을 결정하기 위한 실험적 연구이다. 본 송수기는 물 자체가 가지고 있는 위치에너지에 의하여 작동되어지며, 송수기의 구조는 상단 개구부를 갖는 1개의 수조와 밀폐된 2개의 수조, 5개의 관 그리고 2개의 역지변이 상호 연결되어 있다. 양정과 낙하고 비(H$$/H$$)의 변화에 대한 본 송수기의 수리학적 거동과 작동특성을 조사 연구하기 위하여 각 수조내의 수위와 압력변화를 측정하였으며, 송수기의 수조와 연결관의 직경이 송수기의 양정과 낙하고 비(H$$/H$$)에 미치는 영향을 분석하였다. 본 실험에 의하여 송수기의 효율을 높일 수 있는 효율적인 양정은 낙하고의 약 1/2배 정도이었다. 따라서 효율적인 Cherepnov 송수기를 제작하기 위하여는 낙하고를 양정의 2배정도로 설계해야 할 것으로 판단된다. 수조크기가 효율에 미치는 영향은 5% 이하인 반면 관의 크기가 효율에 미치는 영향은 관크기에 따라 증가되었다.

• 한국ITS학회 논문지
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• 제15권5호
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• pp.54-61
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• 2016

본 연구는 차량-보행자 사고시 보행자의 신장에 따라 보행자의 두부가 승용차의 전면유리에 닿을 수 있는 최저 속도를 제시하기 위하여 수행되었다. 마디모(MADYMO) 프로그램을 사용하여, NF쏘나타 차량에 대하여 보행자의 신장을 160cm, 170cm 180cm로 구분하여 평가하였다. 평가 결과, 승용차의 최저 속도값은 보행자의 신장이 160cm인 경우 약 49km/h, 170cm일 때 약 41km/h, 그리고 180cm일 때 약 29km/h로 나타났다. 이러한 값은 승용차 대 보행자 교통사고에서 승용차의 전면유리에 보행자 두부의 충돌흔적이 있을 시 속도추정의 중요 자료로 활용할 수 있을 것으로 기대된다.

• International Journal of Fluid Machinery and Systems
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• 제5권1호
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• pp.30-37
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• 2012

A two dimensional Darrieus-type turbine has been proposed for the hydropower utilization of extra-low head less than 2m. In a practical use of Darrieus-type hydro-turbine, head and flow rate may be varied temporally and seasonally. Considering that the cost advantage is required for the low head hydro turbine system, the Darrieus turbine should be operated with high efficiency in the wider range of flow rate possibly by using an additional device with simpler mechanism. In the present paper, an adjustment of inlet nozzle section by lowering the inlet nozzle height is proposed to obtain the preferable inlet velocity in low flow rate conditions. Effects of resulting spanwise partial inlet flow are investigated. Finally, an effective modification of inlet nozzle height over flow rate variation is shown.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.926-929
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• 2000

As the track density of hard disk drives increases, there is a need for more precise actuation of the head. This can be accomplished by using a high band width micro-actuator. In this work, the flying characteristics of sliders with micro-actuators are investigated with the aim to optimize the head/disk interface performance of such sliders. Contact-start-stop, sweep, and flying height tests are performed and analyzed. The results show that the MEMS based micro-actuator mounted on a slider possess acceptable flying characteristics.