• 한국패류학회지
• /
• 제28권2호
• /
• pp.137-143
• /
• 2012

큰가리비 치패의 대체 먹이원을 개발하기 위해 각기 다른 먹이원을 공급하여 성장, 생존율 및 체내 조성을 조사하였다. 생존율은 PTE + PHY 실험구에서 90.0%로 가장 높게 나타났다. 각장과 각고는 PHY에서 가장 높게 나타났으나 PTE +PHY 실험구와의 유의적인 차이는 없었다. 반면, PTE와 OTE 단독구는 유의적으로 가장 낮게 나타났다. 한편, 각폭 및 전중량도 동일한 경향을 보여 PHY 단독 실험구와 PTE+PHY 혼합 실험구에서 유의적으로 가장 높게 나타난 반면 PTE와 OTE 단독구는 가장 낮은 값을 보였다. 한편, 체내 지방산 분석에서 DHA 함량은 기존 먹이인 미세조류 단독 실험구 (PHY) 와 경제적인 먹이원인 INS 실험구에 비해 지질강화원인 PTE와 OTE가 혼합된 실험구에서 더욱 높은 것으로 나타났으며, 이러한 높은 값에 기인하여 n-3 PUFA도 높았다. 또한, 총 단백질 함량은 주요 단백질원인 PHY와 INS가 들어간 실험구가 55.5-65.2%의 함량을 보인반면 지질영양강화원만 들어간 PTE, OTE 단독 실험구는 각각 44.8%, 47.0%로 가장 낮은 함량을 나타내었다. 필수아미노산 함량도 동일한 경향을 보여 단순 지질강화원 실험구에서는 낮았다. 한편, 체내 핵산 분석에서 RNA 값은 PHY 단독 실험구와 PTE+PHY 혼합구에서 0.76으로 가장 높게 나타났으나 PTE, OTE 단독구는 각각 0.35, 0.32로 가장 낮게 나타났다. DNA 값도 PHY 단독 실험구와 PTE + PHY 혼합구에서 3.95으로 가장 높게 나타난 반면 PTE, OTE 단독구는 유의적으로 가장 낮았다. 이러한 경향에 의해 RNA/DNA ratio 값도 PHY와 INS가 들어간 단독구와 몇몇 혼합구가 PTE와 OTE 단독구 보다 높았다. 이상의 결과를 통해서 미세조류 단독 공급구인 PHY에 PTE를 혼합해 준 PTE+PHY 혼합 공급구는 큰가리비 치패의 성장, 생존율 및 체내 조성을 향상시켜 주는 것으로 나타났다. 본 실험을 통해 새롭게 대체 개발된 PTE+PHY 혼합구는 이매패류 양식에서 차지하는 미세조류 생산비용의 절감 효과를 기대해 볼 수 있는 것으로 경제적인 측면에서 매우 유용한 결과라 할 수 있다.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
• /
• pp.67-73
• /
• 2001

To investigate the relationships of solder joint characteristics with solder composition and A:V ratio (solder volume per pad area), Sn-37Pb and Sn-4.0Ag-0.5Cu solder balls with 330, 400, 450 and $457{\mu}{\textrm}{m}$ size were reflowed on same substrate. Sn-37Pb and Sn-4.0Ag-0.5Cu was reflowed at $220^{\circ}C$ and $240^{\circ}C$ respectively by IR-type soldering machine. As a result of reflowed solder- ball diameter(D) and height(H) measurement, D/H was decreased with solder ball size increment in range of 330~450 ${\mu}{\textrm}{m}$. But, D/H was increased in the solder joint for 457 ${\mu}{\textrm}{m}$ size, it was caused possibly by decrement of solder ball height increment compared with solder volume increment. As a result of shear and pull test, joint strength with A:V ratio was high. Joint strength of Sn-4.0Ag-0.5Cu was higher than Sn-37Pb. However, Sn-37Pb had more stable solder joint of small standard deviation. A thick and clean scallop type Ni-Cu-Sn intermetallic compound layer was formed in high A:V ratio and Sn-4.0Ag-0.5Cu solder joint interface.

• 한국패류학회지
• /
• 제22권1호
• /
• pp.39-49
• /
• 2006

Ultrastructure of germ cell differentiation during supermatogenesis and the reproductive cycle in male Patinopecten yessoensis was studied by histological and cytological observations. The gonadosomatic index (GSI) in males rapidly increased and reached a maximum in April when seawater temperature gradually increased. Then the GSI gradually decreased from May through July when spawning occurred. Accordingly, monthly changes in the GSI in males coincided with testicular maturation and spawning periods. The sperm morphology of P. yessoensis belongs to the primitive type and showed general characteristics of external fertilization species. The head of the spermatozoon is approximately $3.50{\mu}m$ in length: the sperm nucleus and acrosome are approximately $2.90{\mu}m\;and\;0.60{\mu}m$ in length, respectively. The nuclear type of the spermatozoon is vase in shape, and the acrosome is cone type. The axoneme of the tail flagellum consists of nine pairs of microtubules at the periphery and a pair of central microtubules in the center The satellite body (which is formed by the centriole) and four mitochondria appear in the middle piece of the spermatozoon. The spawning period was from April through July and the main spawning occurred from May to June when seawater temperatures gradually increased. The reproductive cycle of this species can be classified into five successive stages; early active stage (September to November), late active stage (October to March), ripe stage (February to August), spawning stage (April to July), and spent/inactive stage (July to November).

• 한국추진공학회지
• /
• 제21권1호
• /
• pp.26-35
• /
• 2017

원심압축기 운전 중에 발생하는 고주기 피로균열이나 공진 등은 임펠러 파손의 주된 원인이다. 이러한 파손을 회피하기 위해 공진영역 운전에서도 견딜 수 있는 충분한 강도의 임펠러를 설계하거나, 공진이 발생하지 않도록 임펠러를 튜닝 한다. 이러한 회피설계는 임펠러 내부유동 및 성능특성 변화를 야기하게 된다. 본 연구에서는 밀폐형 임펠러에 대해 블레이드 두께를 증가시킨 모델과 스켈럽을 적용한 모델에 대한 유동 및 성능특성을 파악하기 위해 전산해석을 수행하였다. 전산해석 결과, 블레이드 두께 증가 모델 경우는 기본모델 대비 압력계수가 0.5% 감소하였으며, 전효율은 0.1% 감소하였다. 스켈럽 적용모델은 압력계수가 0.4% 증가하였으며, 전효율은 1.6% 감소하였다.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2006년도 춘계 학술대회 개요집
• /
• pp.33-35
• /
• 2006

The interactions between Cu/Sn-Ag-(Cu) and Sn-Ag-(Cu)/Ni interfacial reactions were studied during isothermal aging at $150^{\circ}C$ for up to 1000h using Cu(ENIG)/Sn-3.5Ag-(0.7Cu)/Cu(ENIG) sandwich solder joints. A typical scallop-type Cu-Sn intermetallic compound (IMC) layer formed at the upper Sn-Ag/Cu interface after reflowing, whereas a $(Cu,Ni)_6Sn_5$ IMC layer was observed at the Sn-Ag/ENIG interface. The Cu in the $(Cu,Ni)_6Sn_5$ IMC layer formed on the Ni side was sourced from the dissolution of the opposite Cu metal pad or Cu-Sn IMC layer. When the dissolved Cu arrived at the interface of the Ni pad, the $(Cu,Ni)_6Sn_5$ IMC layer formed on the Ni interface, preventing the Ni pad from reacting with the solder. Although a long isothermal aging treatment was performed at $150^{\circ}C$, no Ni was detected in the Cu-Sn IMC layer formed on the Cu side. Compared to the single Sn-Ag/ENIG solder joint, the formation of the $(Cu,Ni)_6Sn_5$ IMC layer of the Cu/sn-Ag/ENIG sandwich joint effectively retarded the Ni consumption from the electroless Ni-P layer.

• 한국수산과학회지
• /
• 제54권1호
• /
• pp.23-30
• /
• 2021

To examine the optimal temperature, light intensity, and shell-type for shell-living conchocelis production, we tested the shell infiltration of free-living conchocelis fragments under various environmental conditions. Under a combination of various temperatures (10, 15, 20, 25 and 30℃) and light intensities (1, 5, 10, 20, 40, and 80 μmol m-2 s-1), the optimal infiltration conditions of the evaluated three Pyropia species were 20-25℃ and 5-80 μmol m-2 s-1 for P. yezoensis, 20-30℃ and 20-80 μmol m-2 s-1 for P. seriata, and 20-25℃ and 20-80 μmol m-2 s-1 for P. dentata. The infiltration efficiency of free-living conchocelis for different shell types was greater in Korean and Chinese oyster Crassostrea gigas shells than that in scallop Argopecten irradians and clam Meretrix lusoria shells. These results suggest that oyster shells are suitable substrates for shell-living conchocelis production. In conclusion, the present results for optimal infiltration conditions for free-living conchocelis of the three examined Pyropia species will contribute significantly to the production of stable shell-living conchocelis.

• 한국강구조학회 논문집
• /
• 제25권3호
• /
• pp.233-242
• /
• 2013

현재 가장 많이 사용되는 기존 약축접합부는 브라켓 타입으로 기둥과 보를 접합하는 과정에서 수평 스티프너가 필요하며, 기둥과 브라켓의 용접접합으로 인해 용접량이 비교적 많아 접합부에서 취성파괴가 우려된다. 본 논문은 용접플레이트를 사용함으로써 기존 약축접합부가 가지는 문제점에 대한 해결책을 제시할 수 있는 신형상 약축접합부를 제작해 기존 약축접합부 및 표준 약축접합부와 비교하여 구조성능을 평가하였다. 신형상 약축접합부는 H형강 기둥웨브에서 보 단부사이의 거리를 50mm, 100mm, 150mm, 200mm로 하였다. 실험결과 신형상 약축접합부는 H형강 기둥웨브와 보 단부사이의 거리가 150mm일 때 기준 실험값과 가장 비슷한 것으로 나타났으며, 기존 약축접합부와 표준 약축접합부와 비교해 우수한 구조성능을 가지는 것으로 나타났다.

• 한국패류학회지
• /
• 제21권2호
• /
• pp.95-105
• /
• 2005

Gonadosomatic index, reproductive cycle, spermatogenesis and first sexual maturity of Chlamys farreri were investigated by cytological and histological observations, from January 1998 to December 1999. The gonadosomatic index (GSI) rapidly increased in April and reached a maximum in May when seawater temperature rapidly increase. Then the GSI gradually decreased from June to August when spawning occur. Accordingly, monthly changes in the GSI in males coincide with the reproductive cycle. The spermatozoon of Chlamys farreri is the primitive type found in external fertilization species. The head of the spermatozoon is approximately $2.75{\mu}m$ in length including the acrosome measuring about $0.50{\mu}m$ in length, and its tail was approximately $20{\mu}m$, the axoneme of the tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. Five spherical mitochondria around the centriole (the satellite body) appear in the middle piece of the sperm. The spawning period was from June to August and the main spawning occurs from July to August when seawater temperatures are greater than $20^{\circ}C$ The reproductive cycle of this species can be categorized into five successive stages; early active stage (January to March), late active stage (March to April), ripe stage (April to August), partially spawned stage (June to August), and spent/inactive stage (August to January). Over 50% of male scallops attained first sexual maturity between 50.0 and 60.0 mm in shell height, and 100% of those over 60.0 mm in shell height achieved maturity. Accordingly, we assume that male individuals begin reproduction at three years of age.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2006년도 춘계 학술대회 개요집
• /
• pp.30-32
• /
• 2006

The interfacial reaction and reliability of eutectic Sn-Pb and Pb-free eutectic Sn-Ag ball-grid-array (BGA) solders with an immersion Ag-plated Cu substrate were evaluated following isothermal aging at $150^{\circ}C$. During reflowing, the topmost Ag layer was dissolved completely into the molten solder, leaving the Cu layer exposed to the molten solder for both solder systems. A typical scallop-type Cu-Sn intermetallic compound (IMC) layer was formed at both of the solder/Cu interfaces during reflowing. The thickness of the Cu-Sn IMCs for both solders was found to increase linearly with the square root of isothermal aging time. The growth of the $Cu_3Sn$ layer for the Sn-37Pb solder was faster than that for the Sn-3.5Ag solder, In the case of the Sn-37Pb solder, the formation of the Pb-rich layer on the Cu-Sn IMC layer retarded the growth of the $Cu_6Sn_5$ IMC layer, and thereby increased the growth rate of the $Cu_3Sn$ IMC layer. In the ball shear test conducted on the Sn-37Pb/Ag-plated Cu joint after aging for 500h, fracturing occurred at the solder/$Cu_6Sn_5$ interface. The shear failure was significantly related to the interfacial adhesion strength between the Pb-rich and $Cu_6Sn_5$ IMC layers. On the other hand, all fracturing occurred in the bulk solder for the Sn-3.5Ag/Ag-plated Cu joint, which confirmed its desirable joint reliability.