• 수산해양기술연구
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• 제33권1호
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• pp.1-8
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• 1997

To find the tooth selectivity of the dredge for catching the ark shell Scapharca broughtonii, the probabilities of the ark shells which are not sifting through the gaps between teeth were calculated for the various shell lengths. Considering that these probabilities are in proportion to the relative catching efficiencies, selectivity curves for the ark shell dredge were estimated for the various gaps between teeth. The ratio of the shell length of ark shell to the distance between teeth indicating the relative catching efficiencies of 0%, 50%, 100% respectively, were calculated by using these selectivity curves, and the values were 1.00, 1.32, 1.54 in the distance of 4.0cm between teeth and then, the ratios showed a slight tendency to decrease as the distance between teeth increased in the relative catching efficiency of 100%, In addition, the range of shell length for catching, that is, the range of selective shell length by the distance between teeth was 0.54 in the distance of 4.0cm between teeth.

• 수산해양기술연구
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• 제35권4호
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• pp.366-376
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• 1999

In order to examine the catching selectivity of the ark shell(Scapharca broughtonii) dredge, the various factors affecting the selective action of the dredge are analyzed, and the probabilities of the ark shell not shifting through the gaps between the teeth, and the mesh of the netting bag, are calculated for the various shell lengths, using the relation between the posture and the length when the shell passes through these parts.Considering that the probability of making catch is the product of the both probabilities described above, and that this probability is proportional to the relative catching efficiency, the selectivity curves for the ark shell dredge were estimated for various gaps between the teeth and for the various mesh sizes of the netting bag. The obtained results are summarized as follows :1. The ratios of the shell length of ark shell to the distance between teeth indicating the relative catching efficiency of 0%, 50, 100% respectively were 1.0, 1.26~1.28, 1.47~1.44, and that the selection ranges of selective shell length by the distance between teeth were 0.47~0.44, where the distances between teeth were 3.2cm, 3.6cm, 4.0cm, 4.4cm and 4.8cm. 2. The ratios of the shell length of ark shell to the mesh size indicating the relative catching efficiency of 0%, 50%, 100% respectively were 0.67, 0.84, 0.97 and that the selection range of shell length for catching, that in the range of selective shell length by the mesh size was 0.31, where the distance of 4.0cm between teeth, mesh size of 6.0 cm and the smaller mesh angle of $60^{\circ}$3. Where the distance between teeth is 4.0 cm and the smaller mesh angle is $60^{\circ}$, the selection range of shell length for catching of the ark shell dredge is decreased according to the mesh size, and it is minimized by 0.20 in the mesh size of 9.0~10.0 cm, but increased in the mesh size of over 11.0 cm. 4. Where the distance between teeth is 4.0 cm, the selective action by the mesh size of netting bag is begun with the mesh size of over 10.0 cm.

• 대한소아치과학회지
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• 제32권1호
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• pp.49-54
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• 2005

Shell teeth는 매우 드문 상아질 이상으로 상아질 이형성증의 한 형태로서 특징적으로 정상적인 법랑질, 매우 얇은 상아질, 비정상적으로 큰 치수강, 짧아진 치근 등을 보인다. Shell teeth는 1954년 Rushton이 21세 남자 환자에서 나타난 증상을 설명하여 처음 명명하였으며, 1984년 Kinirons이 8세 남아의 shell teeth에 대해 보고하였다. 1992년 Harrison과 Kennedy는 7세 6개월 된 남아에서 보인 shell teeth를 14년간 관찰하여 보고하였는데 이 환아는 유치열과 영구치열 모두 shell teeth가 관찰되었고, 일반적인 shell teeth와 달리 치관에서는 shell teeth의 특징이 나타나지 않았으며, 치근에서만 나타났다. 매우 얇은 상아질과 큰 치수강은 국소적 이형성증에도 관찰되는 특징인데, shell teeth는 전치열에서 보이는데 반해 국소적 이형성증은 한정된 몇 개의 치아에서만 관찰되어 감별진단 할 수 있다. 본 증례는 3세 남아에 관한 것으로 구강내 소견은 모든 유치 치관이 파괴되어 상아질이 노출되어 있었고, 방사선 소견은 얇은 상아질로 둘러싸인 매우 큰 치수강과 확장된 치근관을 보였으며 다수의 소구치가 결손되어 있었다. 환아는 행동조절의 문제 때문에 전신마취하에 치료를 받았다. 현재 환아는 공간유지장치를 장착하고 있으며, 정기적인 관찰이 필요하리라 사료된다.

• 대한장애인치과학회지
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• 제14권1호
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• pp.31-35
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• 2018

부산대학교 치과병원 소아치과에 내원한 Shell teeth에 이환된 소아 환자를 전신마취 하에 치료하였다. 임상검사시 다수 치아의 치관 파괴와 치수 노출 및 상악 유전치 잔존치근이 관찰되었다. 방사선검사상 전반적인 유치열에서 정상보다 큰 크기의 치수강과 넓은 치근관 및 얇은 경조직 층이 존재했으며 발생중인 영구치 치배의 형태이상이 관찰되었다. 환자의 언니와 아버지를 포함한 부계 가족 구성원 일부에서 상아질형성부전증 병력이 조사되었다. 치료시 수복이 불가능한 치아는 발거하였고 보존 가능한 치아는 치수치료 및 기성금속관, 복합레진 수복치료를 시행하였다. 치료 결과 환자의 통증이 감소하였고 저작능력이 회복되었다. 주기적인 내원 및 경과관찰이 요구된다.

• 한국패류학회지
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• 제27권2호
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• pp.91-97
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• 2011

This study examines the morphological features of larval and postlarval shells of the paedomorphic bivalve Crenella decussata Montagu, 1808 from the Sea of Japan. During the early morphogenesis of the shell of C. decussata the following characteristics appear: prodissoconch I -the anterior and posterior provincular teeth, a broad primary ligament pit located on the chondrophore; nepioconch - the anterior and posterior juvenile teeth,primary lateral teeth, fine commarginal and radial sculpture. Larvae of C. decussata distinctly differ from other mytilid larvae by a D-shaped shell, absence of umbo, astraight hinge margin, and homogeneous fine-grained sculpture without co-marginal lines of growth. These shell characters indicate lecithotrophic development of this species. Some morphostructures are revealed which might be used in crenellin taxonomy.

• 수산해양기술연구
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• 제36권4호
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• pp.267-273
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• 2000

민들조개 형망의 갈퀴에 의해 어획될 확률을 조개크기와 갈퀴간격 사이의 관계로부터 구했다. 이때 기존의 방법에서는 각장만을 이용했는데 여기서는 각장 이외에 각고(또는 각폭)에 의한 효과를 추가시켜 어획될 확률을 구하고 로지스틱 어획선택성 곡선에 적합시켰으며, 그식은 다음과 같았다. P=(equation omitted)$.$민들조개의 경우 생물학적 최소형은 각장이 25mm인 것으로 알려져 있으며, 이 최소성숙각장에 대해 50% 어획될 갈퀴간격을 구하면 16.2mm이다. 따라서, 민들조개 형망의 적정 갈퀴간격은 기존에 사용하고 있는 12mm를 16mm로 늘리는 것이 자원보호상 바람직하며, 이것은 예망작업시 모래 속을 끄는 갈퀴의 갯수도 상대적으로 적어지므로 어구저항이 감소되어 연료가 절약되며, 선상에서는 작은 조개를 체를 이용하여 거르는 인력작업도 줄일 것으로 여겨진다.

• 유공압시스템학회논문집
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• 제2권4호
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• pp.23-29
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• 2005

In order to improve the efficiency of hydraulic gear pumps or motors especially for high operating pressure, power losses due to viscous friction and leak flow through gear teeth end-gaps are considered in this paper. Optimal gaps minimizing the power loss for pumps and motors with uniform heights of gaps are analysed first. And the effect of the shapes of gaps with unequal heights on the power loss are studied and discussed by simulation. Considering that the outer shell lacing gear teeth may expand due to high internal pressure or thermal stress, the results drawn in this paper can be used for the design of high efficiency pumps and motors.

• 한국패류학회지
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• 제23권2호
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• pp.155-164
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• 2007

A new species, Arca koumaci Lutaenko et Maestrati n. sp. (Bivalvia: Arcidae), is described from New Caledonia. The species is characterized by the small size, the convex shell with a strong posterior umbonal ridge covered by spikes, the widely curved ventral margin, and presence of cancellate sculpture and convergent marginal teeth. Presence of spikes on the posterior ridge is a unique morphological feature recorded for the first time in the genus. It is proposed that the only subgenus, namely Pliocene A. (Arcoptera) Heilprin, 1887, apart from nominative, can be recognized in the genus. Three morphological types are distinguished within the genus based on shell shape and sculpture. Bathymetric analysis shows that representatives of Arca inhabit water depths down to 175 m, and more than half of Recent species were found below 50 m. Types of A. bouvieri P. Fischer, 1874, Arca boucardi Jousseaume, 1894, Arca avellana Lamarck, 1819, and Arca retusa Lamarck, 1819 are illustrated.

• Parasites, Hosts and Diseases
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• 제21권1호
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• pp.118-124
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• 1983

The distribution, external morphology, radula, chromosome numbers of Planorbidae snails were studied. 1. The specimens were collected at four stations in Nonsangun, Kongjugun, and Daedukgun which are located around Geum river. Three genera and three species of Planorbidae, Hippeutis cantorir Segmentina hemisphaerula and Gyraulus cenvexiusculus, were collected. H. cantori was the most abundant species among the three species. G. convexiusculus was the least abundant one. 2. Each species could be identified on the basis of its external characteristic, since the periphery of each species has a peculiar shape. H. cantori was the largest one among the three species. 3. The radula formula of each species was very similar to other species. The size of radula was proportional to the size of shell. The radula formulae of H. cantori, S. hemisphaerula, and G. convexiusculus were 29 : 1 : 29, 23 : 1 : 23, and 16 : 1 : 16 respectively. The difference of radula formula could be found in the total numbers of laternal and marginal teeth. 4. The haploid chromosome number of H. cantori was eighteen (n=18), S. hemisphaerula and G. convesiusculus were assumed to be same in their chromosome numbers (n: 18).