• 한국자동차공학회논문집
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• 제13권5호
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• pp.82-89
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• 2005

This study was performed to investigate the behavior and spatial distribution of fuel mixtures with different wall angle and diameter of piston cavity in a DI gasoline engine. The spatial distribution of fuel mixtures after impingement of the spray against a piston cavity is one of the most important. factors for the stratification of fuel mixture. Thus, it is informative to understand in detail the behavior and spatial distribution of fuel mixtures after impingement in the cavity. Two dimensional spray fluorescence images of liquid and vapor phase were acquired to analyze the behavior and distribution of fuel mixtures inside cylinder by exciplex fluorescence method. The exciplex system of fluorobenzene/DEMA in non-fluorescing base fuel of hexane was employed. Cavity wall angle was defined as an exterior angle of piston cavity. Wall angles of the piston cavity were set to 30, 60 and 90 degrees, respectively. The spray impinges on the cavity and diffuses along the cavity wall by its momentum. In the case of 30 degrees, the rolling-up moved from the impinging location to the round and fuel-rich mixture distributed at periphery of cylinder. In the case of 60 and 90 degrees, the rolling-up recircurated in the cavity and fuel mixtures concentrated at center region. High concentrated fuel vapor phase was observed in the cavity with 90 degrees. From. present study, it was found that the desirable cavity wall angle with cavity diameter for stratification in a Dl gasoline engine was demonstrated.

• 대한치과교정학회지
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• 제24권3호
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• pp.631-648
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• 1994

The purpose of this study was to investigate the effects of different types of orthodontic force on the root resorption and repair in rat molar. 77 rats were divided into three groups; The control group was not equiped with orthodontic appliance between incisor and first molar. The experimental group was subdivided into closed coil spring subgroup and elastic chain subgroup by the application methods of orthodontic force. Initial orthodontic force between incisor and first molar was 100g. Experimental period was 8 weeks; for 4 weeks the appliance was acting and for another 4 weeks, removed. Root resorption and repair in the root of first molar was examined by light microscope for histologic changes and by inductively coupled plasma spectroscopy(ICP) for quantitative changes. The results were as follows: 1. In the closed coil spring subgroup odontoclasts and root resolution were appeared one week earlier. 2. One week after orthodontic force was eliminated the repair response in the resorptive lacuna was seen in both subgroups. Delayed resorption was seen on the periphery of resorptive lacunae whereas reparative response was seen in the center of lacunae. A new resorption was seen one week after orthodontic force was eliminated. Root contour was partially restored by repairing of resorbed root. 3. The weight ratios of calcium and phosphorous to the sample were decreased during resorptive process but increased during repair process in both the orthodontic groups, but not more than the control group. 4. By different types of orthodontic force (closed coil spring or elastic chain) resorption process was affected but repair process was not.

• Parasites, Hosts and Diseases
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• 제31권3호
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• pp.183-192
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• 1993

Fibricola seoulensis의 고환내 생식세포 및 정자의 미세구조를 관찰하고자 하였다. 실험감염 흰쥐로 부터 회수한 충체를 고정, 탈수 침투 포매, 중합 등의 통상적인 시료제작 과정을 거친 후 JEM 1200EX-ll(JEOL, Japan) 투과전자현미경으로 관찰하였다. 정원세포는 주로 고환의 내벽에서 관찰되었으며 비교적 큰 핵과 상대적으로 적은 세포질을 가지고 있었다. 정모세포는 핵의 량이 세포질 보다 조금 많았고 난형 또는 타원형의 핵을 가지고 있었으며 비교적 염색질의 량이 적었다. 초기의 정자세포는 핵에 비하여 세포질의 량이 훨씬 많았고 핵주위를 사립체들이 둘러싸고 있었다. 발육이 진전된 정자세포에는 끈 모양의 염색질이 나타났고. 세포질에서는 결정체구조가 나타났으며 핵 근처에서는 2개의 축사 뿌리와 중심체가 관찰되었다. 고환과 저정낭에서 무수히 많은 정자의 단면이 관찰되었다 횡단면을 형태학적 특징과 구성요소를 토대로 분류·조합해 본 바 6가지 형으로 대별되었고 정자 부위별 횡단면의 특징적인 형태를 관찰할 수 있었다. F. seoulensis의 정자는 2편모성이었으며 축사는 9쌍의 미세소관과 1개의 core complex로 이루어져서 전형적인 9 + 1형 구조이었다.

• 한국경제지리학회지
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• 제19권3호
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• pp.491-511
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• 2016

본 논문은 세계 자동차산업을 대상으로 2015년판 OECD-TIVA 자료 분석을 통해 구축된 수출품의 해외조달 부가가치 네트워크 특성을 사회네트워크 기법을 활용하여 분석하였다. 그 연구결과를 요약하면 다음과 같다. 첫째, 1995-2011년 기간 동안에 생산공정 분업은 EU, NAFTA와 같은 역내 경제블록에 한정된 것이 아니라 세계적인 차원으로 심화되었다. 둘째, 수출품의 부가가치 해외조달 네트워크는 위계적이고 공간적으로 집중되고 평균거리가 짧아지는 좁은 세상 네트워크의 특성들을 보여주었다. 셋째, 자동차산업 글로벌 가치사슬에서 주요 공급자는 소수의 국가들에 불과하지만 중간재의 사용자는 다수의 국가들이다. 가장 핵심적인 해외 부가가치의 공급자들인 미국, 독일, 중국 간에 특징적인 차이가 존재한다. 생산공정 분업이 글로벌 수준에서 전개된 것은 사실이지만 그 이면에 중심과 주변, 국내와 외국자본의 이분법의 긴장이 놓여 있다.

• 한국패류학회지
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• 제5권1호
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• pp.1-9
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• 1989

A scanning electron microscopic study on the glochidium and glchidial encystment of Anodonta grandis on the guppy was conducted. The shape of the glochidium is apparently triangular and its averge size is 0.45mm X0.4mm when closed, The two glochidial shell valves are of the same size, kept together by a ligament of 120${\mu}{\textrm}{m}$ in length and 7 ${\mu}{\textrm}{m}$ in width. Each of the glochidial shell valves has a 16 ${\mu}{\textrm}{m}$ long hook sitdded with many spines on the superior face. A large area to the apex of the valve surrounding the base of the hook is provided with numerous small spines which become progressively smaller towards the periphery of the area, The external surface of the glochidial shell valve is covered with numerous small processes showing successive change in the shape and the pattern of destribution by part. Besides the processes, there are a number of niches scattered all over the exterior surface. The glochidial shell valve has two layers. One is the outer thin membrane bearing the processes and the niches and the others is the inner layer bearing numerous holes which any accessory structure and 2.65 ${\mu}{\textrm}{m}$ in diameter, emerges from a canal located at center of ventral plate of the mamtle, A total of three types of the hair cells are observed. In present artificial infection of the glochidium to the guppy, it took about three to four hours to complete an early cysts, During the period of encystment, The epithelial cells of the host fish actively migrated toward the attached glochidium and covered it.

• 한국의류산업학회지
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• 제24권4호
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• pp.451-459
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• 2022

This study aimed to develop a a custom-made dress form for draping using a live model's 3D body scan obtained from an entry-level 3D handheld scanners, 3D modeling software and 3D printing technology. A female subject was recruited whose body size fell under the normal (N) body shape criteria suggested by KS K 0051. First, the handheld scanner reduced the length of the legs in scanning, but most of the scanning operations between the neck and crotch levels were conducted accurately. Therefore, this study was designed to develop a torso dress form. The full body 3D scan was edited into a torso shape using ZBrush® software. Using Rhinoceros^® and Materialise's Magics software, a 3D body scan was modeled so that the user could fit two types of mannequin stands (one with a neck fixation from above and one with an insert from below) to the dress form. The body scan was divided into 9 pieces to fit the printable size of the Stratasys 3D printer Fortus 250mc, and the cross-sectional distance from the center to the periphery was downsized by 2 mm. After outputting the dress form scan file with a 3D printer, the dress form was manufactured by the first covering it with a 4 oz nonwoven pad and the second covering with a single jersey material.

• 한국패류학회지
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• 제27권4호
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• pp.377-386
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• 2011

The ultrastructures of germ cells during spermatogenesis and sperm morphology in male Mya arenaria oonogai, which was collected on the coastal waters of Samcheonpo, south coast of Korea, were investigated by transmission electron microscopic observations. In the early stage of the spermatid during spermiogenesis, a few granules and a proacrosomal granule, which is formed by the Golgi complex, appear on the spermatid nucleus, and then it becomes a proacrosomal vesicle. Consequently, it becomes an acrosome by way of the process of acrosome formation. The morphologies of the sperm nucleus type and the acrosome of this species have a curved cylindrical type and cone shape, respectively. The spermatozoon is approximately $48-50{\mu}m$ in length including a curved cylinderical sperm nucleus (about $2.65{\mu}m$ long), an acrosome (about $0.64{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$ long). As some ultrastructural characteristics of the acrosomal vesicle, the peripheral parts of two basal rings show electron opaque part (region), while the apex part of the acrosome shows electron lucent part (region). These charateristics of the sperm belong to the family Myidae or some species of Veneridae in the subclass Heterodonta, unlike a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part (region). Therefore, it is easy to distinguish the families or the subclasses by the acrosome structures. Exceptionally, In particular, a cylinder-like nucleus of the sperm is curved (the angle of the nucleus is about $20^{\circ}$), as seen in some species of Veneridae (range from $0^{\circ}-80^{\circ}$). The number of mitochondria in the midpiece of the sperm of this species are four, as one of common characteristics appeared in most species except for a few species in Veneridae in the subclass Heterodonta. Cross-sectioned axoneme of the sperm tail flagellum shows a 9+2 structure: the axoneme of the sperm tail flagellum consists of nine pairs of peripheral microtubules at the periphery and a pair of central doublets at the center.

• Journal of Radiation Protection and Research
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• 제38권4호
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• pp.194-201
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• 2013

To investigate monitoring unit (MU) efficiency and plan quality of volumetric modulated arc therapy (VMAT) using flattening-filter free (FFF) photon beam in association with target size and location. A virtual patient was generated in Eclipse$^{TM}$ (ver. A10, Varian Medical Systems, Palo Alto, USA) treatment planning system. The length of major and minor axis in axial view was 50 cm and 30 cm, respectively. Cylindrical-shaped targets were generated inside that patient at the center (symmetric target) and in the periphery (asymmetric target, 7.5 cm away from the center of the patient to the right direction) of the virtual patient. The longitudinal length was 10 cm and the diameters were 2, 5, 10 and 15 cm. Total 8 targets were generated. RapidArc$^{TM}$ plans using TrueBeam STx$^{TM}$ were generated for each target. Two full arcs were used and the axis of rotation of the gantry was set to be at the center of the virtual patient. Total MU, homogeneity index (HI), target mean dose, the value of gradient measure and body mean dose were calculated. In the case of symmetric targets, averaged total MU of FFF plan was 23% and 19% higher than that of flattening filter (FF) plan when using 6 MV and 10 MV photons, respectively. The difference of HI, target mean dose, gradient measure and body mean dose between FF and FFF was less than 0.04, 2.6%, 0.1 cm and 2.2%, respectively. For the asymmetric targets, total MU of FFF plan was 21% and 32% was higher than that of FF when using 6 MV and 10 MV photons, respectively. The homogeneity of the target was always worse when using FFF than using FF. The maximum difference of HI was 0.22. The target mean dose of FFF was 3.2% and 4.1% higher than that of FF for the 6 MV and 10 MV, respectively. The difference of gradient measure was less than 0.1 cm. The body mean dose was higher when using FFF than FF about 4.2% and 2.8% for the 6 MV and 10 MV, respectively. No significant differences between VMAT plans of FFF beam and FF beam were observed in terms of quality of treatment plan. The HI was higher when using FFF 10 MV photons for the asymmetric targets. The MU was increased noticeably when using FFF photon beams.

• 대한전자공학회논문지SP
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• 제39권1호
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• pp.61-69
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• 2002

능동 스테레오 비젼 시스템은 목표물 판별을 위해서 간단한 연산만으로 작은 시차값을 가지는 특징들만을 통과시킴으로써 목표물 위치 측정을 가능케 한다. 그런데 이 간단한 방법은, 복잡한 배경이 포함되거나 시차가 영인 영역에 다른 물체들도 동시에 존재하면 적용이 어렵게 된다. 이러한 문제점들을 해결하기 위하여, 본 논문에서는 시야 중심 영역의 해상도는 높이고 일반적으로 중요도가 낮은 주변의 해상도는 감소시키는 포비에이션 기법을 필터링 방법과 결합시켰다 포비에이트 영상 표현을 위하여 영상 피라미드 또는 로그폴라 변환을 사용하였다. 또한 추적이 수행되는 동안에 스테레오 시차가 작은 값이 유지되도록 투영을 이용하여 스테레오 시차를 추출하였다. 실험 결과는 로그폴라 변환이 복잡한 배경으로부터 목표물을 분리하는 제안된 방법이 영상 피라미드 또는 기존 방법보다 우수하며, 추적성능을 상당히 개선함을 보여주고 있다.

• 센서학회지
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• 제10권2호
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• pp.91-100
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• 2001

CMOS 공정기술을 이용하여 물체의 윤곽검출을 위한 픽셀수 $8{\times}8$의 방사형 구조 시각칩을 설계 및 제조하였다. 일반적으로 시각칩은 광입력의 센싱, 물체의 윤곽검출과 움직임 검출 등을 수행하며 본 연구에서는 물체의 윤곽검출에 중점을 두었다. 방사형 구조의 픽셀 분포는 시각칩이 중심부분으로 갈수록 높은 해상도를 가지게 하며, 이러한 구조는 선택적인 영상데이터의 감소를 가능하게 한다. 또한 윤곽검출을 위한 시각칩에서는 처음으로 적용된 구조이다. 방사형 구조를 형성하는 원주들 사이의 픽셀의 크기차이 때문에 출력전류를 보정해 줄 수 있는 메커니즘이 필요하게 되며, 본 연구에서는 이를 위해 MOS 트랜지스터의 채널의 폭을 스케일링하는 방법을 사용하였다. 설계된 칩은 $1.5{\mu}m$ single-poly double-metal 표준 CMOS 공정기술을 이용하여 제조되었다.