• 환경생물
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• 제41권1호
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• pp.54-59
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• 2023

Lovenia elongata is a member of the family Loveniidae and is one of the most common tropical echinoids. This species has a broad distribution range in the sub- and tropical regions of the Indo-Pacific Ocean, extending from the Mozambique to the Hawaiian Islands, and from southern Japan to northern Australia. It is commonly found in subtidal areas and on coral reefs within these regions. This species was for the first time recorded from the Ulleungdo Island, Korea. This species is characterized by a teardrop-shaped test that reaches up to 5 cm in length, with a deep groove at the front and tapered at the back end. The petaloid is not obvious, and the primary spines are long and banded. This study is the first to report the newly recorded L. elongata in Korea.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.753-760
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• 2007

For protection of the cylinder wall of the ball mill for grinding raw ore. the inner side of the cylinder is covered with rubber liner. The rubber is easily worn down because the rubber relatively soft compared with raw ore. So the rubber liner in the ball mill cylinder must be replaced almost every year and the cost for replacing rubber liner formidable. In this paper, for reducing or excluding the cost of replacing rubber liner the basalt liner is designed. The basalt materials are generally harder than raw ore and the basalt liner in the ball mill does not wear down and so it can be used almost permanently. The concave surfaces are made on the liner of the ball mill and the liner in the cylinder wall plays also the role of raising the steel balls mixed in the raw ore. The section profiles of the concave surface have an important effect on the performance of the ball mill. The deep concave grooves raise the steel balls to high levels and give the large potential energy to the steel balls impacting to the raw ore. But if the concave grooves are too deep. the steel balls raised too high by the concave grooves fly along the parabolic path and reach to the other side of cylinder wall and so the steel balls do not play the roles of grinding the raw ore. The forces acting to a steel ball in a concave groove of the cylinder liner are also analyzed in this paper. The formulas calculating the height and the impact point of the steel ball are introduced and presented. Based to these formulas, the optimum section profiles of the basalt liner are presented.

• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.1051-1058
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• 2020

The chemical mechanical planarization (CMP) is a process of physically and chemically polishing the semiconductor substrate. The planarization quality of a substrate can be evaluated by the within wafer non-uniformity (WIWNU). In order to improve WIWNU, it is important to manage the pad profile. In this study, a device capable of non-contact measurement of the pad thickness profile was developed. From the measured pad profile, the profile of the pad surface and the groove was extracted using the envelope function, and the pad thickness profile was derived using the difference between each profile. Thickness profiles of various CMP pads were measured using the developed PMS and envelope function. In the case of IC series pads, regardless of the pad wear amount, the envelopes closely follow the pad surface and grooves, making it easy to calculate the pad thickness profile. In the case of the H80 series pad, the pad thickness profile was easy to derive because the pad with a small wear amount did not reveal deep pores on the pad surface. However, the pad with a large wear amount make errors in the lower envelope profile, because there are pores deeper than the grooves. By removing these deep pores through filtering, the pad flatness could be clearly confirmed. Through the developed PMS and the pad thickness profile calculation method using the envelope function, the pad life, the amount of wear and the pad flatness can be easily derived and used for various pad analysis.

• 환경생물
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• 제33권4호
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• pp.375-382
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• 2015

We discovered three soil ciliates of the class Colpodea-Colpoda henneguyi Fabre-Domergue, 1889; C. lucida Greeff, 1888; and Bursaria truncatella $M{\ddot{u}}ller$, 1773 from Obong-ri, Ayajin-ri and Elwang-ri (Korea), respectively. Colpoda henneguyi had the following features: often wider preorally than postorally, size in vivo $60-80{\mu}m{\times}50-70{\mu}m$; extrusomes indistinct in vivo, cylindroid approximately $1{\mu}m$ long; notches caused by deep diagonal groove; yellowish globules on the cortex of the cell; 10-12 postoral kineties; silverline system aspera-type. Colpoda lucida exhibited the following features: broadly reniform, size in vivo $70-90{\mu}m{\times}50-70{\mu}m$; conspicuous extrusomes, $3.5-5{\mu}m$ long in vivo, cylindroid to fusiform; 13-16 postoral kineties; silverline system cucullus-type. Bursaria truncatella had the following features: bursiform, size in vivo $300-470{\mu}m{\times}120-260{\mu}m$; macronucleus coiled with highly variable shapes, $600-1100{\mu}m{\times}30-40{\mu}m$ long in vivo; micronuclei 16-25 in number, approximately $4{\mu}m$ in diameter; extrusomes cylindroid, $3-4{\mu}m$ long in vivo. This is the first report of colpodean ciliates from Korea, and we describe these species based on observations of live and impregnated (protargol and silver nitrate impregnation) specimens.

• 한국어류학회지
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• 제11권1호
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• pp.29-32
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• 1999

1995년 남해 거제도 부근에서 채집된 어류를 동정한 결과 지금까지 우리나라에서는 서식이 알려지지 않은 Chaunax abei와 Bembrops curvatura로 확인되어 이 2종을 한국산 미기록종으로 보고한다. C. abei는 외부형태적으로 C. fimbriatus와 유사하나 체표의 녹색 무늬 형태가 원형이고 등지느러미의 앞쪽에는 노란 반점과 그 뒤에 약간 패인 곳이 없으며, 유인돌기와의 주변에는 돌기가 없다는 점이, 그리고 B. curvatura는 B. caudimacula와 유사하나 뒷지느러미 연조수 및 측선린 수와, 측선이 깊게 내려간 점 그리고 제 1 등지느러미의 첫 번째 막이 검다는 점 등이 이들 유사종들과 잘 구별되었다. 이들의 한국명으로는 Chaunacidae "점씬벵이과", Chaunax "점씬벵이속", C. abei를 "점씬벵이"로, 그리고 B. curvatura는 "줄굽은눈퉁이"라고 명명하였다.

• 한국어류학회지
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• 제23권4호
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• pp.310-313
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• 2011

퉁돔과에 속하는 Aprion virescens 1개체(표준체장 151.4 mm)가 제주연안에서 자망으로 처음 채집되었다. 이 종은 눈 앞에 세로로 깊게 파인 홈이 있고, 가슴지느러미는 매우 짧아 주둥이 길이와 비슷하며 등지느러미에 선명한 4개의 점이 존재한다. 이 미기록종의 속명과 국명은 "녹색퉁돔속", "녹색퉁돔" 이라고 각각 제안하였다.

• Tribology and Lubricants
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• 제8권2호
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• pp.64-72
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• 1992

The recent trends of rotating machinery demand high speed and high temperature operation, and the bearing with new material is required to be developed. Ceramic, especially silicon nitride, have been receiving attention as alternative material to conventional bearing steel. Ceramic ball bearing offers major performance advantages over steel bearing, for instance, high speed, maginal lubrication, high temperature, improved corrosion resistance and nonmagnetic capabilities etc.. In this paper, the mechanical characteristics of ceramic ball bearing (hybrid ceramic bearing and all ceramic bearing) were investigated, and the characteristics of ceramic bearing were compared with that of steel bearing. Deep groove ball bearing 6208 was taken the object of analysis. The main results of analysis were followings: the radial stiffness of hybrid and all ceramic bearing were 112% and 130% that of steel bearing, and the axial stiffness of all ceramic bearing was 110% that of steel bearing. According as rotating speed was up, the ball load, the contact angle, the contact stress and the spin-to-roll ratio between ball and raceway of ceramic bearing were far smaller than these of steel bearing. And there was not a significant difference between the minimum film thickness of ceramic bearing and steel bearing. It is expected that this research is contributed to enhanced fundamental technology for the practical applications of ceramic ball bearing.

• 펄프종이기술
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• 제40권4호
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• pp.66-73
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• 2008

When coated paperboard is printed, pressed into a groove with a creasing rule and folded, white line cracking occurs along the crease due to intensive mechanical pressure. The cracking will deteriorates product quality and waste resources. Effects of creasing pressure and ink dosage on the foldability of coated board were investigated. It was shown that applying an optimum pressure is important during creasing. When the pressure was too low, the crease formed was not sufficiently deep enough to enable precise folding. When an excess pressure was applied, fiber bonding was destroyed, resulted in unsatisfactory cracking. When the coated board was folded in machine direction (MD), long cracks were formed along MD. When it folded in cross direction (CD), the cracks were shorter and formed perpendicular to CD. Printing promoted cracking due to the decrease in flexibility of coated board. In addition, uneven ink film layer on the coating layer caused worse cracking.

• Restorative Dentistry and Endodontics
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• 제40권2호
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• pp.161-165
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• 2015

Three-dimensional (3D) reconstruction of cone-beam computed tomography (CBCT) scans appears to be a valuable method for assessing pulp canal configuration. The aim of this report is to describe endodontic treatment of a mandibular second premolar with aberrant pulp canal morphology detected by CBCT and confirmed by 3D modeling. An accessory canal was suspected during endodontic treatment of the mandibular left second premolar in a 21 year old woman with a chief complaint of pulsating pain. Axial cross-sectional CBCT scans revealed that the pulp canal divided into mesiobuccal, lingual, and buccal canals in the middle third and ended as four separate foramina. 3D modeling confirmed the anomalous configuration of the fused root with a deep lingual groove. Endodontic treatment of the tooth was completed in two appointments. The root canals were obturated using lateral compaction of gutta-percha and root canal sealer. The tooth remained asymptomatic and did not develop periapical pathology until 12 months postoperatively. CBCT and 3D modeling enable preoperative evaluation of aberrant root canal systems and facilitate endodontic treatment.

• 한국지형학회지
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• 제19권4호
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• pp.27-37
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• 2012

본 연구는 강원도 철원군 명성산 화강암과 현무암 용암대지 사이의 접촉대인 한탄강 승일교 인근 지역의 독특한 경관을 형성하고 있는 화강암 하천 침식 및 퇴적 지형과 풍화 지형 분석을 다루고 있다. 주요 화강암 지형으로서는 심층풍화된 구릉, 면상침식지형, 고지형면 및 고토양, 하천작용과 관련된 미지형으로 돌개구멍과 그루브, 램 파트형의 암괴, 사주와 사력퇴, 그리고 구하상 등이 있다. 그리고 풍화가 덜 진전된 구릉의 일부로 하천의 측방이동을 방해하는 화강암 하식애 지형이 있다.