• Journal of Aquaculture
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• v.9 no.1
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• pp.73-81
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• 1996

This study was conducted to study the reproductive cycle in female fusilier, Caesio diagramma by using the histological methods. Histological changes of the ovary were well correlated with the patterns of gonadosomatic index (GSI) and hepatosomatic index (HSI). GSI was increased in April as the value of HSI increase and reached to its maximum in May and June. Oocytes at the chromatin-nucleolus and peri-nucleolus stages were observed in the ovary throughout the year. In April, oocytes containing yolk appeared in ovaries of a few fishes. Most oocytes appearing in May and June belonged to the tertiary yolk stage. Frequency of oocytes appearance at the tertiary yolk stage in May and June was higher than that of the other months. Moreover, the empty follicles and atretic oocytes were observed in the ovaries with many vitellogenic oocytes during these two months. Thereafter, oocytes of the yolk stage disappeared in September. The spawning period of C. diagramma is from the month of April to June, and this species belongs to an asynchronous and multiple spawner.

• Journal of Aquaculture
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• v.7 no.1
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• pp.21-39
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• 1994

In order to study the optimum environmental condition for larvae culture of the freshwater crab, Eriocheir japonicus, larvae from different growth stages and young crab were cultured under the 16 different conditions of $4\times4$ temperature-salinity combinations (4 different temperatures at 22, 24, 26, $28^{\circ}C$ with 10.5, 17.5, 24.5 and $31.5\%$ of salinity). The duration of metamorphosis, metamorphosis rate, the interval of moulting period, and survival rate were measured from each experimental group of larvae and young crab under the different conditions. The results indicated that the optimum conditions may be a $24.5\%o$ of salinity at water temperature at 22, 24, and $26^{\circ}C$. At $28^{\circ}C$ with $24.5\%o$), the duration of metamorphosis reduced somewhat, nevertheless metamorphosis and survival rate decreased a lot. And the lower the salinity showed the lower the metamorphosis and survival rates at $28^{\circ}C$.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.264-266
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• 2004

본 연구에서는 4차 암모늄염의 대전방지 현상을 알아보기 위하여 아크릴기가 있는 2-(dimethyl amino)ethyl methacrylate(DMA)를 알킬화 시켜 대전방지제를 합성하고, 자외선 경화 반응을 통해 대전방지 기능이 지속적으로 유지되게 하였다. 여기에서 얻어진 대전방지제를 PMMA 판에 코팅하여 코팅 도막의 전기저항의 변화를 관찰한 결과, 대전방지제의 함량이 20part 이상으로 높아질 때 표면저항 값이 낮아지는 현상을 볼 수 있었다. 또한 대전방지제의 함량이 10part인 경우, 상대습도가 $20\%$ 증가할 때 저항 값은 $10^2{\Omega}/cm^2$까지 감소하는 결과를 볼 수 있었다.

• Korean Journal of Food Science and Technology
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• v.14 no.4
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• pp.342-349
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• 1982

Filefish muscle in the form of thin plate $(5{\times}10{\times}0.4\;cm)$ was dried in a forced air dryer at $47.5^{\circ}C$ to study the relation between dehydration mechanism and water activity. The dryer was designed in such a way that the temperature, relative humidity and velocity of air could be controlled. The whole dehydration process of the filefish muscle was divided into two different drying rate periods, constant and falling rate period. During the constant drying rate period, the drying rate was proportional to the square root of air velocity under the conditions of constant temperature and relative humidity of air. The falling rate period was further divided into two different falling drying rate periods, first and second falling rate period. The first falling rate period was an unsaturated surface drying period caused by partial unsaturation of the drying surface with capillary condensed free water diffused from the internal part of the filefish muscle. At this stage he drying rate was mainly dependent on the relative humidity at constant air temperature, and case-hardening phenomenon started at the end of this stage. The moisture content and the water activity at which the second falling rate period started were not constant, because the drying rate of the first falling rate period was strongly dependent on the air humidity. The second falling rate period was again divided into two drying rate periods, former and latter period. The drying rates of both of these periods were independent on the external air humidity. During the former period of the second falling rate period, the dehydration was proceeded by diffusion and vaporization of capillary condensed free water in filefish muscle. The diffusion coefficient of water was $2.89{\times}10^{-10}m^2/sec\;at\;47.5^{\circ}C$. At this stage, the case-herdening continued until the water activity reduced to 0.7. The latter period of the second falling rate period started at the water activity of 0.45. The dedydration was proceeded by diffusion and vaporization of bound water, which adsorbed in multimolecular layers, through the hardened drying surface. The number of molecular layers was 4, and the diffusion coefficient of water during this stage was $4.38{\times}10^{-11}m^2/sec\;at\;47.5^{\circ}C$.

• The Korean Journal of Quaternary Research
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• v.2 no.1
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• pp.25-50
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• 1988

The survival of rich evidence of palaeolithic occupation found in the Imjin-Hant'an River basin was possible due to many fortuitous geological conditions provided there. Formation of the basalt plain in a narrow valley system which developed during the late Mesozoic insured the appearance of a basin of sedimentation in which archaeological sites would be preserved with relatively minor post-depositional disturbance. Geomagnetic and K-Ar dating indicates that lava flows occurred during the Brunes Normal Epoch. During and after the process of basin sedimentation, erosion of the plain was confined to the major channel of the present river system which developed along the structural joints formed by the lava flow. Due to characteristic columnar structure and platy cleavage of the basalt bedrock, erosion of the basalt bedrock occurred mainly in vertical direction, developing deep but narrow entrenched valleys cut into the bedrock. Consequently, the large portion of the site area remained intact. Cultural deposits formed on top of the basalt plain were left unmodified by later fluvial disturbances due to changes in the Hant'an River base-level, since they were formed about 20 to 40m above the modern floodplain. Sedimentological evidence of cultural deposits and palynological analysis of lacustrine bed formed in the tributary basin of the Hant'an River indicate that hominid occupation occurred in this basin under rapidly deteriorating climatic conditions. From three thermoluminescence dates, the timing of hominid occupation as represented by 'Acheulian-like' bifaces apparently occur sometime during 45,000 BP. Thus, deposition of cultural layers in this basin approximately coincides with the beginning of the second stadial of the final glacial, during which the Korean Peninsula must have had provided a sanctuary for prolonged human occupation.

• Journal of the Korean Geophysical Society
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• v.2 no.1
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• pp.39-44
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• 1999

High-resolution images are drawn from existing seismic data which were originally obtained by Korea Ocean Research & Development Institute (KORDI) during 1994-1997 for deep seismic studies on the East Sea of Korea. These images are analyzed for mapping Quaternary faults and near-bottom gas pockets. First 12 channels are selected from shot gathers for reprocessing. The processing sequence adopted for high-resolution seismic images comprises data copy, trace editing, true amplitude recovery, common-midpoint sorting, initial muting, prestack deconvolution, bandpass filtering, stacking, highpass filtering, poststack deconvolution, f-x migration, and automatic gain control (AGC). Among these processing steps, predictive deconvolution, highpass filtering, and short window AGC are the most significant in enhancement of resolution. More than 200 Quaternanry faults are interpreted on the migrated sections in the shallow depths beneath the seafloor. Although numerous faults are found mostly at the western continental slope and boundaries of the Ulleung Basin, significant amount of the faults are also indicated within the basin. Many of these faults are believed to be formed with reactivation of basement, from geotectonic activities including volcanism, and often originated in Tertiary, indicating that the tectonic regime of the East Sea might be unstable. Existence of shallow gas pockets casts real hazardous warnings to deep-sea drillings and/or to underwater constructions such as inter-island cables and gas pipelines. On the other hand, discovery of these gas pockets heightens the interests in developing natural resources in the East Sea. Reprocessed seismic sections, however, show no typical seismic characteristics for gas hydrates such as bottom-simulating reflectors in the western continental slope and ocean floor.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.3
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• pp.273-277
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• 1981

This study was carried out in 1979 to establish the proper mulching culture method for an aromatic tobacco, ST 375-4. Three different methods of mulching were employed: Improved mulching (I. M.), General mulching (G. M.) and Non-mulching (N. M.). The number of seedlings per hole was 5 for I. M., and one for G. M. and N. M. In comparison with N. M., I. M. had shortened final date of leaf harvest by 14 days, enabling curing leaves before the rainy season. It also reduced transplanting labour hours by 44.9%. Yield and price value increased with improved mulching culture. There was little difference in relative light intensity at leaves between N. M. and I. M.

• Journal of Sericultural and Entomological Science
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• v.16 no.2
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• pp.133-139
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• 1974

The objective of this study is to compare the effects of raw materials as method of speeding up mounting of matured silkworm, for reducing concentrated labor during mounting periods. The results obtained from this study are summarized as fellows： (1) Quercus acutissima Carrs showed the most remarkable effect of repellent. Persicaria blumei Gross and Artemisia asiatica Nakai were followed in order. The rest repellents were also expected to be applicable. considering known material (silk-up) with lower mounting percentage. (2) The effective methods of preparation of repellent were to make distillate. Decocted solution type was considered to be the easiest way of preparation. (3) It seemed to be that there was little effect of repellent on the qualities of cocoon and silk. (4) When a repellent was applied to a silkworm bed, immatured silkworms were observed to mount. Thus it suggests that the repellent will give remarkable effects only when the degree of matured of silkworms is uniform.

• Korean Journal of Soil Science and Fertilizer
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• v.2 no.1
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• pp.49-51
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• 1969

Manuring has been classified into five stages to study the absorbtive and metabolic process of potassium in the period of growth of soybeans. The contents in harvest time have not shown much difference regardless of earlier or later manuring. But in the testing period of comparatively earlier manuring, supply of potassium has precipitated the synthesizing of carbohydrates, and in the testing period of comparatively later manuring, decrease of not only soluble sugar, but also soluble nitrogen and protein-nitrogen has been discoverd thus resulting in the existence of connection between supply of potassium and nitrogen metabolism.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.4
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• pp.469-472
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• 1983

Seasonal variations influence the growth duration and yield of soybeans in the tropics and subtropics. Results of different yield trials were used to determine the relationship between yield with days to R$_1$ and R$_{8}$ in different seasons. Similarly relationship for 100 seed weight was examined. Multiple regression equations suggest that increase in yield can be obtained by increasing the days to R$_{8}$ regardless of seasons. However, increasing the days to R$_1$ invariably reduced the yield. The longer the time from R$_1$ to R$_{8}$, the higher the 100 seed weight. Since the population examined was heterogeneous for photoperiod sensitivity, the need to examine photoperiod sensitive and insensitive selections separately is discussed.