강화재의 복잡한 배열로 인하여 복합재 구조에 대한 유한요소 모델링은 상당히 까다로운 문제가 될 수 있다. 본 논문에서는 복합재 구조에 대하여 효율적으로 주기 격자망을 생성시킬 수 있는 기법을 제안한다. 먼저 육면체 유한요소로 구성된 규칙적인 격자망을 준비하고, 이를 복합재 내의 강화재에 대한 표면 정보에 맞추어 깎아낸다. 강화재와 기지재 사이에서 깎여진 육면체 유한요소는 임의의 절점과 면을 가질 수 있는 다면체 유한요소에 해당한다. 일관된 알고리즘을 이용하여 육면체 유한요소를 깎아내기 때문에 강화재와 기지재 사이의 요소는 자동적으로 적합한 형태로 구성된다. 또한 대표체적영역 내에서 강화재의 주기성을 추가적으로 고려하면, 대표체적영역에 대한 각각의 주기 경계 쌍에서 절점과 요소의 형태가 모두 일치하는 주기 격자망을 효율적으로 생성시킬 수 있다. 그러므로 별도의 처리 없이 대표체적영역에 주기 경계조건을 부여할 수 있다. 수치예제에서는 본 논문에서 제안한 기법의 효용성을 검증한다.

The effect of sudden changes of water temperature (WT) on the survival rate and physiological responses of the red spotted grouper (Epinephelus akaara) were examined by manipulating WT control system for 9 days. Experimental condition was divided in two different regimes at low (from 10°C to 4°C, decreased 1℃/d) and high (from 28°C to 34°C, increased 1°C/d) WT. Survival rate of experimental fishes were observed, and determined the changes of hematological characteristics by analyzing plasma levels of cortisol, glucose, total protein, and electrolytes (Na+, Cl–, K+). No mortality was observed until low WT 6°C (144 h) and high WT 32°C (96 h), and 100% mortality was observed at low WT 4°C (216 h) and high WT 35°C (171 h). Plasma levels of cortisol and glucose increased rapidly as decreasing WT, and the loss of swimming ability and respiration response was observed at low WT 7°C and high WT 34°C conditions.

We observed the osteological development of larval and juvenile red spotted grouper (Epinephelus akaara) in order to generate data for the assessment of skeletal deformities and to inform phylogenetic systematics research. Larvae and juveniles were obtained from a aquafarm in Muan-gun, Jeolla-namdo Province, Korea. The average water temperature at the time of breeding was 23.0°C and average water salinity was 33.0 psu. Freshly hatched fish larvae had not undergone any ossification, but ossification of the parasphenoid bone, which forms the base of the cranium, occurred as the juveniles reached an average body length (BL) of 2.49 mm. At the same time, ossification of the preopercle and opercle occurred in the operculum, and ossification of the maxilla, which forms the upper jaw, and the dentary bones, which form the lower jaw, began. In addition, ossification of the vertebra occurred by formation of 7 vertebral centra and the neural spine in the abdominal vertebra. When the juveniles reached an average (BL) of 5.22 mm, ossification of the nasal, lateral ethmoid, and alisphenoid bones occurred in the cranium; ossification of the endopterygoid and metapterygoid bones began in the palatine region; and ossification of the hypohyal and interhyal bones occurred in the hyoid arch. At an average (BL) of 20.9 mm, ossification of the basisphenoid bone in the cranium and the suborbital bone in the orbital region occurred. Ossification of the vertebra then occurred by the formation of long pairs of ribs from the third to the ninth abdominal vertebrae, completing osteological development.

This study was conducted in order to examine the egg development in red spotted grouper, Epinephelus akaara and the morphological development of its larvae and juveniles, and to obtain data for taxonomic research. This study was conducted in June 2013, and 50 male and female fish were used for the study. One hundred μg/kg of LHRHa was injected into the body of the fish for inducing spawning, and the fish were kept in a small-sized fish holder (2×2×2 m). Eggs were colorless transparent free pelagic eggs, 0.71–0.77 mm large (mean 0.74±0.02 mm, n=30), and had an oil globule. Hatching started within 27 h after fertilization. Pre-larvae that emerged just after hatching were 2.02–2.17 mm in total length (mean 2.10±0.11 mm), their mouth and anus were not opened yet, and the whole body was covered with a membrane fin. Post-larvae that emerged 15 days post hatching were 3.88–4.07 mm in total length (mean 3.98±0.13 mm), and had a ventral fin with two rays and a caudal fin with eight rays. Juveniles that were formed at 55 d post hatching, were 31.9–35.2 mm in total length (mean 33.6±2.33 mm), with red color deposited over the entire body, and black chromophores deposited in a spotted pattern. The number of fin rays, body color, and shape were the same as that in the adult fish.

The gonadosomatic index (GSI), gonadal development and changes in hormones in plasma level of the indoor cultured grunt (Hapalogenys nitens) were investigated by histological study from August 2011 to October 2012. The GSI showed similar trends with gonad developmental stages during the culture periods. Changes in plasma level of estradiol-17β of female H. nitens reached the highest value before the spawning period, and seasonal changes in plasma level of estradiol-17β were similar in trends of oocyte developments and GSI changes. Testosterone levels of male H. nitens reached the highest value before and after the spent stage. Ovarian developmental stages of H. nitens could be classified into early growing stage, late growing stage, mature stage, ripe and spawning stage, recovery and resting stage. The testicular developmental stages could be divided into growing stage, mature stage, ripe and spent stage, and recovery and resting stage.