• Anatomy and Cell Biology
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• 제57권2호
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• pp.271-277
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• 2024

Human dentition is unique to individuals and helps in identification of individuals in forensic odontology. This study proposes to study the manually ground sections of single rooted teeth using digital methods for dental age estimation. To assess the dentinal translucency from the scanned digital images of manually ground section of teeth using commercially available image edition software. Corroborating the root dentinal translucency length and region of interest (ROI) of translucency zone in pixels (as a marker of dental age) with the chronological age of the subject, as stratified by different age groups. Twenty single-rooted extracted teeth from 20 patients each from 6 groups divided as per age. Manual sectioning of the teeth followed by scanning the sections was done. Root area in pixels and ROI of translucency zone were measured. From the observed values, translucency length percentage (TLP) and percentage of ROI in pixels (TPP) was calculated and tabulated. Pearson's correlation coefficients were obtained for age with TLP and TPP. Positive correlation existed between age and TLP and also between age and TPP. With the obtained data, multilinear regression equations for specific age groups based on 10-year intervals were derived. By a step-down analysis method, age was estimated with an average error of around ±7.9 years. This study gives a novel method for age-estimation that can be applied in real-time forensic sciences.

• 대한치과교정학회지
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• 제18권2호
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• pp.329-342
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• 1988

In methods of finding causes for cleft palate, many cases have been studied by investigators using teratogenic agents. Among them, a synthetic agent known as triamcinolone acetonide (TA) was widely used. When this drug was injected into mice during palatogenesis, it induced lowered body weight and a deformed mandible. But many cases have been studied on growth changes, only of the developmental stages of the palate. Therefore, the objective of this study was to evaluate craniofacial growth in experimentally induced cleft palate mice after finishing palatogenesis namely just before birth. Normal, alcohol treated, and TA treated DDY mice were obtained at 18-days of gestation and heads were prepared for serial sectioning in the sagittal plane. The midsagittal sections were photographically enlarged (${\times}40$) and measurements made to asses the amount of growth. The obtained results were as follows. 1. The incidence of cleft palate was 41.2% when TA was injected. 2. The body weight of the cleft palate group was lower than the control group. 3. In the cleft palate group, mandibular length (H-M) was lighter than the control group. 4. In the cleft palate group, degree of staining was not distinct compared to the control group by the double staining method. 5. In the cleft palate group, anteroposterior posture of the tongue tip to facial plane (C-M) was more posterior than the control group. 6. The cause of posterior posture of the tongue tip to facial plane (C-M) in the cleft palate group, was not short and retracted tongue but the mandibular length was increased. 7. The anteroposterior relationship of hyoid cartilage to cranial base was the same in all groups.

• 비파괴검사학회지
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• 제25권4호
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• pp.254-261
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• 2005

지금까지 한국인의 치아 통계는 매우 부족한 상태이고, 대부분 치아형태의 정보를 얻기 위해 방사선학적 방법을 이용하거나, 치아를 절단하는 등의 방법으로 연구를 해왔다. 이와 같은 방법은 오랜 시험 기간을 필요로 하고 정밀도가 낮고 파괴적인 방법을 주로 이용한 것이므로, 이제는 한국인의 표준 치아에 대한 정밀한 데이터를 얻기 위해 새로운 비파괴적인 시험이 필요하다. 이를 위하여 각각의 하악 제1소구치를 미세단층촬영기(Micro-CT, SkyScan, Belgium)를 이용하여 $21.31{\mu}m$의 해상도로 교합면에 대한 수평면으로 0.022mm 로 Scan을 하였다. 이를 통하여 내 외부 형태학적 중요부위를 측정하였으며, 영구 치아의 평균 치수표로 사용했었던 G. V. Black(1836-1915)에 의해 제시된 수치와 비교하였다.

• 한국강구조학회 논문집
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• 제11권2호통권39호
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• pp.143-151
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• 1999

본 논문에서는 냉간성형 profiled steel sheeting과 보통강도의 콘크리트로 이루어진 합성보의 휨거동에 관한 연구를 통하여 새로운 형식의 보부재의 사용가능성을 검토하였다. 합성보의 비선형거동을 추적하기 위하여 profiled steel sheeting, 철근 및 콘크리트의 재료비선형을 포함할 수 있는 해석적 방법을 개발하였으며, 합성보의 비선형 모멘트-곡률 관계를 나타낼 수 있는 Power Model식을 제시하였다. Power Model은 원래 보-기둥 접합부의 모멘트-회전각과의 관계를 예측하기 위해 제안된 것이나 합성보에 맞게 수정하였다. 합성보의 하중-처짐 거동은 Power Model에 의한 모멘트-곡률 관계를 이용하여 변위조절법인 단계별 수치적분법을 적용하여 계산하였으며, 실험결과와 비교하였다.

• 대한기관식도과학회지
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• 제12권2호
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• pp.19-25
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• 2006

There have been numerous modalities to recover blink function of orbicularis oculi muscle in patients with facial paralysis. However, there is still no optimal method for reanimation of eyelid. In this study, we tried to recover blink function of paralyzed rabbit's eyelid with the ion polymer metal composite (IPMC) which is one of the electroactive polymers that is spotlighted as artificial muscle. We manufactured IPMC by plating the platinum over perfluorosulphonic acid polymer ($Nafion^{(R)}$). IPMC was coated by Norland optical adhesive for the purpose of insulation and keeping it from dry. IPMC modifications by roughening the surface of Nafion, repetitive plating (maximum 4 times) with platinum, and lengthening the width of IPMC were done. The facial paralysis was induced in the rabbit by sectioning of facial nerve at the main trunk. After minimum period of 4 weeks, IPMC was inserted in the paralyzed rabbit's eyelid. By modification, the force generated by IPMC was enhanced. Restoration of blink function in paralyzed rabbit was achieved on electrical stimulation of the IPMC by 5 voltage direct current. IPMC can be promising option for facial reanimation, but further studies are needed to enhance the efficiency of IPMC.

• Journal of the Optical Society of Korea
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• 제15권3호
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• pp.252-263
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• 2011

In this work, for the first time, the quality of restoration in wide-field microscopy images after deconvolution was analyzed as a function of different Point Spread Functions using one deconvolution method, on a specimen of known size and on a biological specimen. The empirical Point Spread Function determination can significantly depend on the numerical aperture, refractive index of the embedding medium, refractive index of the immersion oil and cover slip thickness. The influence of all of these factors is shown in the same article and using the same microscope. We have found that the best deconvolution results are obtained when the empirical PSF utilized is obtained under the same conditions as the specimen. We also demonstrated that it is very important to quantitatively check the process' outcome using several quality indicators: Full-Width at Half-Maximum, Contrast-to-Noise Ratio, Signal-to-Noise Ratio and a Tenengrad-based function. We detected a significant improvement when using an indicator to measure the focus of the whole stack. Therefore, to qualitatively determinate the best deconvolved image between different conditions, one approach that we are pursuing is to use Tenengrad-based function indicators in images obtained using a wide-field microscope.

• 대한치과교정학회지
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• 제41권4호
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• pp.224-236
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• 2011

본 연구는 정상교합자의 치열궁과 기저골 형태를 파악하기 위해 시행하였다. 정상교합자 27명(남-15명: 25Y $10M{\pm}4Y$ 4M/여-12명: 26Y $1M{\pm}7Y$ 4M)을 대상으로 두개골의 전산화 단층촬영을 시행하고 입체영상을 제작한 뒤, 상악 중절치의 FA point의 중점을 원점으로 하는 3차원 좌표계를 형성하였다. 또한 상악 교합평면과 평행한 면으로 절단하여 상하악의 치열궁과 기저골의 형태에 대해 분석하였다. 상하악기저골은 A point, B point 부위와 양측 제1대구치 부위의 좌표에서 통계적으로 유의한 차이가 나타나지 않았다. 또한 상하악의 치열궁은 기저골악궁에 비해 전치부에서 순측으로 위치하였다. 또한 치열궁과 기저골악궁의 협설측 교차는 상악은 대구치 부위에서, 하악은 소구치 부위에서 이루어졌다.

• 마이크로전자및패키징학회지
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• 제15권2호
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• pp.47-54
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• 2008

컴포넌트에서의 비정상적인 금속간화합물 성장이 보드 레벨 기계적 신뢰성에 미치는 영향을 연구하기 위하여, 전기 도금된 Ni/Au UBM과 Sn2.5Ag0.5Cu 솔더의 리플로우 횟수 및 고온 시효 시간에 따른 금속간 화합물 성장거동을 관찰하였다. 각 조건별로 처리된 컴포넌트에서 솔더 접합부의 기계적 특성을 비교하기 위하여, 전단 속도 변화에 따른 볼 전단 시험을 실시하여 전단에너지 값을 측정하였다. 마지막으로, 보드 레벨에서의 기계적 신뢰성 시험을 위하여 조건별로 처리된 컴포넌트를 PCB 보드에 실장하여, 3점 굽힘 시험 및 충격 시험을 실시한 후 파괴모드를 분석하였다.

• The Journal of Advanced Prosthodontics
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• 제2권4호
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• pp.117-121
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• 2010

PURPOSE. The present study was intended to evaluate the effect of soldering techniques with infrared ray and gas torch under different gap distances (0.3 mm and 0.5 mm) on the tensile strength and surface porosity formation in Ni-Cr base metal alloy. MATERIALS AND METHODS. Thirty five dumbbell shaped Ni-Cr alloy specimens were prepared and assigned to 5 groups according to the soldering method and the gap distance. For the soldering methods, gas torch (G group) and infrared ray (IR group) were compared and each group was subdivided by corresponding gap distance (0.3 mm: G3 and IR3, 0.5 mm: G5, IR5). Specimens of the experimental groups were sectioned in the middle with a diamond disk and embedded in solder blocks according to the predetermined distance. As a control group, 7 specimens were prepared without sectioning or soldering. After the soldering procedure, a tensile strength test was performed using universal testing machine at a crosshead speed 1 mm/min. The proportions of porosity on the fractured surface were calculated on the images acquired through the scanning electronic microscope. RESULTS. Every specimen of G3, G5, IR3 and IR5 was fractured on the solder joint area. However, there was no significant difference between the test groups (P > .05). There was a negative correlation between porosity formation and tensile strength in all the specimens in the test groups (P < .05). CONCLUSION. There was no significant difference in ultimate tensile strength of joints and porosity formations between the gas-oxygen torch soldering and infrared ray soldering technique or between the gap distance of 0.3 mm and 0.5 mm.

• 대한조선학회논문집
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• 제38권4호
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• pp.75-82
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• 2001

건조 후 수행하는 수압시험 또는 화물의 적재 등과 같은 정하중은 파랑변동하중에 비하여 선체구조물에 상당히 큰 응력을 유발한다. 이러한 정하중이력에 의하여, 선체구조물의 응력집중으로 인해 피로강도가 문제되는 용접이음부에서는, 재료의 탄소성 거동에 의하여 초기용접잔류응력이 상당히 이완될 것으로 예상된다. 따라서, 이러한 용접이음부의 피로강도를 평가할 때에는 이완된 잔류응력의 영향을 고려하는 것이 보다 합리적이다. 본 연구에서는 선체구조물의 여러 가지 용접형태 중 Padding plate가 용접된 형태에 대하여 정하중이력($0.5{\sigma}Y,\;0.85{\sigma}Y$)에 의한 초기 용접잔류응력의 변화를 측정하며, 잔류응력의 변화가 피로강도에 미치는 영향을 검토한다.