• Journal of Species Research
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• 제11권3호
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• pp.174-179
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• 2022

In this study, we identified two marine synchaetid rotifers, Synchaeta grimpei Remane, 1929 and S. vorax Rousselet, 1902, in Korea, which are the first synchaetid rotifers collected from a marine environment in the country. Prior to this study, all six synchaetids recorded in Korea were collected from freshwater environments. The morphological characteristics of both species are consistent with those recorded in previous studies of each species. Synchaeta grimpei is distinguished from other synchaetid rotifers by its cone-shaped body, wide and flat apical field, indistinct auricles, and long foot with two separated small toes. The morphological characteristics of Korean S. vorax specimens were most similar to the original description of Rousselet (1902), with its slender and cylindrical trunk shape, strongly convex apical field, and short foot with two small, separated toes. The rami of the Korean S. vorax specimen contained one frontal hook and several distinct and large teeth. Here, we provide the morphological diagnoses of the two synchaetid rotifers and the sequences of the partial mitochondrial cytochrome c oxidase subunit I (COI) of the two species.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제26권1호
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• pp.1-14
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• 2023

Foreign body (FB) ingestion is a common health problem that affects children more than adults. According to gastroenterologists' guidelines, the management of FB ingestion differs slightly between adult and children. This review aimed to compile adult and children guidelines and establish an understandable association to reveal the requirements and timing of the endoscopic procedure, which is the most effective and least complicated technique for gastrointestinal FBs. Coins, pins, and chicken and fish bones have been the most commonly ingested FBs. However, with their increasing use in recent years, large batteries with lithiumion conversion, stronger magnets composed of rare earth metals, such as neodymium, and superabsorbent objects have become the most morbid and mortal, necessitating new management strategies. Although the approach to gastrointestinal FBs is controversial, with different treatment options available in different disciplines, many studies have demonstrated the efficacy and safety of endoscopic procedures. Many factors influence the timing of endoscopy, including the nature, size, and location of the ingested object and the patient's clinical condition.

• 한국해양공학회지
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• 제30권3호
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• pp.201-207
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• 2016

In this paper, an aluminum pressure vessel (cylinder) for a 200 m water depth is designed and analyzed. Because of their lack of usage in the deep sea, only a few papers about pressure vessels subjected to external pressures have previously been published. Moreover, the high level of imported external-pressure-vessel products limits the academic pursuit. Yet, research on internal pressure vessels is widely available because of their broad usage at onshore. This paper presents the process of basic designing and modelling of pressure vessels using the design rules of American Standard of Mechanical Engineering (ASME) Section VIII Division 1. To promote understanding, finite element analysis (FEA) result of an existing sample cylinder which was not designed by ASME code is compared with the design obtained in this paper. Several methodologies are used for the finite element analysis, including rectangular, cylindrical, and axisymmetric coordinate, to attain an accurate stress result. Same dimensions except the thickness of the cylinder and loading condition of 0.200 MPa was given for the current study. Finally, a rigorous design procedure is added for the bolt and boundary conditions of the cylindrical body and its ends. The obtained stress level satisfies the allowable design stress value specified in the ASME code.

• 한국농공학회지
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• 제30권2호
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• pp.67-81
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• 1988

The purpose of the present study is to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir and to establish a solid foundation for the automatic optimum structural design combined with finite element analysis. The major design variables are the dimensions and steel areas of each member of the structures. The construction cost which is composed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of the working stress design method. The corresponding design guides including the standard specification for concrete structures have been also employed in deraving the constraint conditions. The present nonlinear optimization problem is solved by SUMT method. The reinforced concrete intake-tower is decomposed into three major substructures. The optimization is then conducted for both the whole structure and the substructures. The following conclusions can be drawn from the present study. 1. The basis of automatic optimum design of reinforced concrete cylindrical shell structures which is combined with finite element analysis was established. 2. The efficient optimization algorithms which can execute the automatic optimum desigh of reinforced concrete intake-tower based on the working stress design method were developed. 3. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optImization algorithms developed in this study seem to be efficient and stable. 4. The difference in construction cost between the optimum designs with the substructures and with the entire structure was found to be small and thus the optimum design with the substructures,rnay conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the tensile stress insteel for salb, the minimum lonitudinal steel ratio constraints for tower body and the shearing stress in concrete, tensile stress in steel and maximum eccentricityconstraints for footing, respectively. 6. The computer program develope in the present study can be effectively used even by an unexperienced designer for the optimum design of reinforced concrete intake-tower.

• 대한조선학회논문집
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• 제56권6호
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• pp.507-514
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• 2019

Computational studies of accelerating flow around 2D Circular Cylinder was performed to investigate characteristics of wake field and drag forces. Previous studies had revealed that drag on the cylindrical body in accelerating flow is much greater than that in the flow with constant velocity; however, the underlying physics on the drag increase has not been clearly investigated. In order to investigate the drag increase and its relationship with wake development, this study employed a finite-volume based CFD code, Fluent 13.0 with k-ω SST model for turbulence effects. Inflows are modeled with varied accelerations from 0.4905 to 9.81m/s². The drag computed in the present study is in good agreement with previous studies, and clearly shows the increase compared to the drag on the body in the flow with constant velocity. The results also show that drag crisis observed at high Reynolds number in the case of the flow with constant velocity is also found in the case of accelerating flow. The analysis for wake and recirculation length shows that conventional vortex shedding does not occur even at high Reynolds number and the drag increase is larger at higher acceleration.

• 환경생물
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• 제39권4호
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• pp.423-434
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• 2021

Two new free-living marine nematodes of the genus Belbolla Andrássy, 1973 belonging to family Enchelidiidae are newly described based on specimens obtained from a shallow subtidal sediment of the western and southern outermost islands of Korea. Belbolla koreensis sp. nov. differs from other species of the genus by the combination of the following characteristics: longer body length (3,080-3,462 ㎛ long), eight oesophageal bulbs in the posterior region of pharynx, well-developed two winged precloacal supplements (anterior precloacal supplement slightly longer than posterior one: 47-59 ㎛ vs. 43-46 ㎛ long), strongly arcuated, very thick, L-shaped spicule (122-127 ㎛ long, 1.7-1.9 anal body diameter(a.b.d.) long) with three separated blunt distal tips, and well-developed relatively long cylindrical shaped gubernacular apophysis with blunt teeth covering two thirds of the dorsal margin (57-58 ㎛ long, 0.8-0.9 a.b.d. long). Belbolla hoonsooi sp. nov. is characterized by the following combination of characteristics: longer body length (3,494 ㎛ long), eight oesophageal bulbs in the posterior region of pharynx, well-developed two winged precloacal supplements (anterior precloacal supplement slightly longer than posterior one: 43 ㎛ vs. 36 ㎛ long), strongly arcuated, L-shaped spicule (119 ㎛ long, 1.5 a.b.d. long) with three separated blunt distal tip, and well-developed relatively long inverted triangle shaped gubernacular apophysis with blunt teeth covering half of the dorsal margin (45 ㎛ long, 0.6 a.b.d. long). Detailed morphological characteristics and illustrations of two new Belbolla nematodes from the Korean seawaters were provided by differential interference contrast microscopy. Comparative tables on biogeographical and morphological characteristics of Belbolla species are also provided herein.

• 한국안광학회지
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• 제21권3호
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• pp.259-264
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• 2016

목적: 유발된 난시성 흐림이 정적균형을 유지시키는 다른 감각기관들에 미치는 영향을 분석하여 신체 안정성을 감소시키는 원인을 규명하고자 하였다. 방법: 평균 나이 $23.40{\pm}2.70$세의 20명을 대상으로 하였다. 근시성 단성난시를 유발하기 위해 (+)원주렌즈의 축을 양안에 $180^{\circ}$(직난시), $90^{\circ}$(도난시), 그리고 $45^{\circ}$(사난시) 방향으로 위치시켰으며, 각각의 방향에 +0.50 D, +1.00 D, +1.50 D, +2.00 D, +3.00 D, +4.00 D, 그리고 +5.00 D의 원주렌즈를 이용해 각 난시유형별로 난시성 흐림을 증가시켰다. TETRAX biofeedback system을 이용하여 각 조건에 따른 안정성 지수(ST)와 각 감각기관에 해당하는 4가지 주파수의 흔들림 강도(SP)를 측정하였다. 결과: 난시성 흐림이 커질수록 유발된 모든 난시유형에서 ST는 완전교정상태와 비교해 증가하였지만, 유발된 사난시에서만 유의한 차이를 보였다. 난시성 흐림이 증가함에 따른 ST의 증가와 각 주파수별 SP간의 상관분석결과, 유발된 사난시에서 신체 안정성을 저하시키는 원인으로 체성계(중 고주파수), 중추신경계(고주파수), 말초전정계(중 저주파수), 그리고 시각계(저주파수)의 영향 순으로 높은 상관성을 보였다. 결론: 미교정된 사난시로 인한 시각정보는 신체균형을 유지시키는 모든 감각기관의 정상적인 기능을 방해하여 신체 안정성을 감소시킬 수 있다. 따라서 최적의 난시교정은 신체균형의 불안정성을 제거시키는 중요한 요인이 될 수 있다.

• 한국전자파학회논문지
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• 제17권9호
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• pp.900-912
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• 2006

본 논문에서는 1.575 GHz에서 운용되는 미사일 탄두 탑재형 GPS 수신 안테나를 원형 패치 안테나 구조로 미사일 탄두부의 중간에 장착하였으며, 원형 링 구조의 단락 핀을 이용하여 패치면과 접지면을 연결하였다. 제안된 안테나는 이중 급전과 이중 급전점의 위상 차이를 이용하여 미사일 비행 축과 수직한 방향(H-면)에서 무지향성의 방사 특성을 갖도록 설계되었다. 유전체로 1.6 mm 높이의 $FR4(\varepsilon_r=4.6)$를 사용하였으며 무지향성 방사패턴은 원형 패치 직경 59.5 mm, 단락 핀 직경 14 mm일 때 최적화되었다. 또한 실제 미사일 형태를 갖도록 직경 100 mm, 길이 500 mm의 원통형 몸체를 탄두 하단부에 장착하였다. 이때 이중 급전점의 사이각과 이중 급전점의 위상을 변화시키면서 H-면에서의 방사 패턴의 변화를 측정하였으며 그 결과, 이중 급전점의 사이각과 이중 급전점의 위상 차이가 각각 $100^{\circ}$일 때 이득 -5.55 dBd, 최대/최소 방사 전력 레벨 차 3.98 dB를 갖는 무지향성에 가까운 방사 패턴 특성을 얻을 수 있었다.

• 대한치과교정학회지
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• 제41권4호
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• pp.280-287
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• 2011

Objective: This study compared the stability of cylindrical miniscrews (Cy, 7 mm in length) with that of tapered miniscrews (Ta, 5 mm in length), using torque values to determine if the healing time before loading affects the stability of the miniscrew and if the insertion torque is associated with the removal torque measured after a few weeks of healing. Methods: Ta and Cy with different thread lengths were placed in the tibias of 12 female New Zealand white rabbits (body weight: 3.0 - 3.5 kg), and the maximum insertion torque values (ITV) were measured. No orthodontic forces were applied so as to allow us to determine the pure effects of the different shapes. After 3 different healing periods (2, 4, and 6 weeks), maximum removal torque values (RTV) were measured immediately before the rabbits were sacrificed. Results: No miniscrews were loosened. There were no significant differences in ITV or RTV between the Ta and Cy nor were there any significant differences in the ITV and RTV between the 3 groups, which had different healing periods. There was a correlation between the ITV and RTV. Conclusions: Shorter Ta showed similar stability as Cy, as determined by torque values. This result strongly suggests that the tapered shape is more advantageous than the cylindrical shape. The RTV did not increase significantly over time. It is recommended that a miniscrew be loaded immediately; waiting a few weeks before loading should be avoided. The correlation between the ITV and RTV suggests that the ITV can be used to estimate a screw's future stability.

• 한국임상수의학회지
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• 제37권5호
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• pp.242-248
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• 2020

An intestinal strigeiid trematode, Apharyngostrigea pipientis, was detected from Ardea cinerea jouyi, Egretta intermedia and Nycticorax nycticorax between July, 2006 and June, 2020 in Daejeon metropolitan city and Kangwon-do, Republic of Korea. It was observed with a light and scanning electron microscope (SEM), and molecularly analyzed with 18S rRNA genes. The infection rate of the strigeiid trematode was 25.9% (7/27). The body is cylindrical in whole mount, greatly elongated in outline and shows a strong dorsal curvature. The overall measurements are: length 4.1-4.8 mm; fore-body 1.00-1.20 mm by 0.8-0.9 mm; hind-body 3.2-3.6 mm by 0.43-0.46 mm. The body is covered by a relatively thick cuticle, devoid of spines. The oral sucker leads into a short esophagus that is devoid of a muscular pharynx. The holdfast organ is enormously developed. The vitelline follicles distributed dorsal wall of fore-body and hind-body. This strigeiid trematode especially differs from other species of genus Apharyngostrigea in morphology. Although these A. pipientis are several morphological distinctions from Apharyngostrigea cornu, the partial sequence of 18S rRNA showed the sequence homology of A. pipientis (99.9%) and A. cornu (99.8%), and this result revealed their conspecific relationship between A. cornu and A. pipientis. This is the first report of A. pipientis in the Republic of Korea.