• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.4
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• pp.241-250
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• 1992

This study was covered the amount of food consumed per day as well as methods estimating the daily food consumption per fish of Agrammus agrammus in natural population to understand flow of food organisms among trophic levels in bio-community of the coastal waters, Shinsudo, Samchonpo. The estimating formulas were induced from the mathematical models that representing the diurnal fluctuation of the stomach fullness of the fish. The daily food consumption could be estimated by both feeding rates and gastric evacuation rates, but it was more reasonable method that based on gastric evacuation rates than feeding rates. The daily food consumption in wet weight per fish by gastric evacuation rates were 1.9856g/day, 3.4725g/day, 4.4418g/day, 5.8168g/day, and 7.2113g/day in the order of age groups from 0 to 4. The daily rations as percentage of body weight were $9.35\%,\;6.65\%,\;5.76\%,\;4.72\%\;and\;5.31\%$ in the order of ages. The daily food consumption was proportional to the body weight of fish, but the daily food consumption per specific body weight was reciprocal to the body weight. Annual food consumption in wet weight. per fish by gastric evacuation rates were 529.98g from the age of 0.25 to 1.0, 1,269.28g from the age of 1.0 to 2.0, 1,622.76g from the age of 2.0 to 3.0, 2,125.57g from the age of 3.0 to 4.0, 1,316.09g from the age of 4.0 to 4.5 The amount of food consumed per fish during 4.25 years, from the age of 0.25 to 4.5, was 6,863.68g in wet weight. the relationships between the daily food consumption(Dr) by gastric evacuation rates and the total length(L, cm) or the body weight(W, g) were as follows: $$Dr=0.036L^{1.702}$$ $$Dr=0.254W^{0.664}$$

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.151-157
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• 2015

Recent laboratory studies have documented that mixotrophic dinoflagellates Dinophysis spp. and heterotrophic dinoflagellate Oxyphysis oxytoxoides share a common prey, i.e. the mixotrophic ciliate Mesodinium rubrum. Nonetheless, very little is known about the population dynamics and species interactions among these protists in natural environments. To investigate the interactions between the dinoflagellate predators and their ciliate prey in the field, we took the samples twice a day from 26 July to 28 August, 2011 at a fixed station in Masan Bay and analyzed their abundances. During this study, salinity was highly variable, ranging from 5 to 28, due to the periodic input of rainfalls to the sampling station. Water temperature was on average $26.5^{\circ}C$ until 20 August and thereafter was about $21^{\circ}C$ by the end of the sampling period. The ciliate M. rubrum occurred persistently throughout the sampling period, ranging from 13 to $492\;cells\;mL^{-1}$. Cell densities of D. acuminata and O. oxytoxoides ranged from undetectable level to $19,833\;cells\;L^{-1}$ and from undetectable level to $100,333\;cells\;L^{-1}$, respectively. The high abundance of D. acuminata mostly followed the blooming of the ciliate M. rubrum, but it often did not peak even during heavy blooms of the prey, probably due to sensitivity to large salinity fluctuation and also presumably overlapped grazing by other mixotrophic dinoflagellates. The abundance of O. oxytoxoides was detected only when water temperature was lower than $24^{\circ}C$, indicating that water temperature is an important environmental factor to control the population dynamics of the dinoflagellate species.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.220-230
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• 1992

Soil temperature is one of the important environmental factors which control all the physical, chemical and biological processes in soil including germination and root growth of plants and other organisms living in the soil ecosystem. Soil water and nutrient availability and mobility are temperature dependent. Soil temperature change is depended primarily upon energy exchange in soil surface, meteorological variance and physical properties of the soils which are closely related to heat transfer mechanism. In this study physical properties including bulk density, soil texture and organic matter content were measured and thermal diffusivity on the soils was calculated. Soil samples from the 66 meteorological stations under the Korea Meteorology were collected and the physical parameters were measured. To obtain relationship between thermal diffusivity and soil water content a heat probe thermal diffusivity measurement apparatus was designed and used in this experiment. According to the survey on soil physicsal properties on the 66 meteorological stations, the 52% of the surface soil texture were sandy loam and laomy sand or sand, 38% were loam and silty loam, and 10% were clay loam and silty clay loam. The bulk density which was closely related with thermal properties showed average of $1.41g/cm^3$ for sandy soils, $1.33g/cm^3$ for loam and silty loam soils, and $1.21g/cm^3$ for clay loam and silty clay loam soils. The apparent thermal diffusivity of the upper layer from 0 to 30cm ranged from 1.16 to $8.40{\times}10^{-3}cm^3/sec$ with average of $3.53{\times}10^{-3}cm^3/sec$. The apparent thermal diffusivities of the Jeju soils of which organic matter contents were high and the bulk densities were low were near $2{\times}10^{-3}cm^3/sec$. The thermal diffusivity of snow measured in Chuncheon ranged from 0.822 to $2.237{\times}10^{-3}cm^3/sec$. The damping depth calculated from the thermal diffusivity ranged from 5.92 to 13.65cm for daily basis and 124 to 342cm for yearly basis. The significant regression equation to estimate thermal diffusivity with bulk density and soil water content was obtained by the heat probe in laboratory.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.284-292
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• 2012

To date, chemical control remains the most common way to reduce beet armyworm (Spodoptera exigua) populations. However, this insect has become more tolerant or resistant to many chemical insecticides and the insect larvae usually hide inside hollow, tube-like leaves of host plant so they were difficult to kill by spraying insecticides. The use of viral and bacterial insecticide to solve these problems has not been successful because of their novel feeding habit. To overcome these problems, in this study, the biological characteristics and virulence of an entomopathogenic fungus isolated from the cadaver of larvae beet armyworm were investigated. Isolated entomopathogenic fungus was identified as Nomeraea rileyi (Farlow) Samson by morphological examinations and genetic identification using sequences of the ITS, ${\beta}$-tubulin gene and EF1-${\alpha}$ regions. This fungus was named as N. rileyi SDSe. Virulence tests against 3rd larvae of beet armyworm were conducted with various conidial suspensions from $1{\times}10^4$ to $10^8$ conidia/ml of N. rileyi SDSe in laboratory conditions. Mortality rate of beet armyworm showed from 20 to 54% and the virulence increased with increasing conidial concentrations. Although N. rileyi SDSe showed low mortality rate against beet armyworm, it is expected that N. rileyi SDSe will be used effectively in the integrated pest management programs against the beet armyworm.

• 한국해양학회지
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• v.30 no.4
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• pp.320-331
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• 1995

The closely spaced cores were analyzed to find detailed reconstruction of paleoenvironments and sealable changes along the Delaware Bay coast. Three areas, Kitts Hummock Beach mars, the St. Jones River marsh, and Bowers marsh near the St. Jones River's mouth, were chosen because these areas are compose of their own geomorphic characteristics and sea-level history. since significance of the stratigraphic correlations was to determine sedimentary fancies and paleoenvironments, multidisciplinary methods such as lithological description, grain-size analysis, organic/inorganic content, water content, mineral composition, botanical analysis, micropaleontological analysis, and /SUP 14/C datings were performed. Five major divisions of marsh environments were recognized in the stratigraphic sections: freshwater marsh, initialfreshwater marsh, slightly brackish marsh, brackish marsh, and salt marsh. Most of the lower part in the stratigraphic sections show freshwater marsh. On the top of this, either brackish marsh or tidal flat/tidal stream was recorded. The pro-Holocene sediments consist of sand, mud, and sandy mud, The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene sediments consist of sand, mud, and sandy mud. The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene surface within short distances permitted the concurrent development of variable environments such as freshwater marsh, brackish marsh or salt marsh at similar elevations. The freshwater marsh in this case was formed in the areas of isolation, so saline-water cannot encroach upon these areas. This complex development of paleoenvironments leads to a difficulty in stratigraphic correlation and interpretation of local relative sea-level changes. The deposition of subsurface sediments was affected by sediment supply, compaction, fluvial activity, biological competition, local tectonics and isostacy, climate and local relative sea-level changes. It was interpreted that the positions in the changes from freshwater environments to brackish environments or ice versa are the turning points of transgressions and regressions. Therefore, multiple transgressions and regressions were identified in the stratigraphic sections of the study area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.59-67
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• 1983

An experiment on the rearing of tilapia stocked in closed recirculating tanks eliminating biological filter beds was carried out at the Fish Culture Experiment Station of the National Fisheries University of Pusan, from May 18 through October 21, 1982, and the growth rates, feed conversion, water quality, spawning prevention and space utilization efficiency were discussed. Finally discussed is the feasibility on the establishment of commercial production units. On the water quality, the water temperature ranged from $22.8^{\circ}C\;to\;29.1^{\circ}C$, and total ammonia arround 10 ppm or slightly up. Maintaining phytoplankton bloom was not successful probably because of the active consumption by the heavily stocked tilapia. Several attempts were made by changing the culture water with green water from a nearby earthen pond with results of fading-away in a couple of days. Feed conversions were relatively high ranging from 0.9 to 1.2 except for experiment 1 when the fish were not fully recovered from weakened wintering state. The feed used was partly laboratory prepared $25\%$ protein diet and mostly commercially available $39\%$ protein carp feed. Spawning was completely controlled during the experiment, resulting from density effect, which ranged from 10kg to 40.7kg per square meter with water depth of 0.5 to 0.6m. Space utilization efficiency was very high. Daily net production from the experiment division 3, which showed the highest result, was 6.206 kg per tank, which is calculated 3,235 metric tons per hectare per year, This time, water temperature ranged from 27.8 to $29.1^{circ}C$, average being $28.4^{circ}C$, and total ammonia arround 10 ppm. An estimation for the commercial set-up of the production system based on the results of experiment divisions which had initial stocking rate $15\;kg/m^2$ or up, is made. If the total facility, 8 tanks comprising $56\;m^2$ in surface area, is used for the present study, the yield would become 5,639 kg from 200 day rearing, which would be possible under double sheets vinyl house without additional heating, and it is thought feasible in the economic view point, when 10 or more units are operated.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.61-70
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• 2004

Environmentally sound control of Japanese lawngrass cutworm, Spodoptera depravata with Korean entomopathogenic nematodes (Heterorhabditis sp. Gyeongsan, Steinernema carpocapsae GSNI , S. glaseri Dongrae, S. longicaudum Nonsan, and S. monticolum Jiri) was evaluated in the laboratory and field. In addition, effect of turf height on the pathogenicity of entomopathogenic nematodes and density of ant (Formica japonica) and spine-tailed earwigs (Forficula scudderi) were investigated in the field. The corrected mortality of 3rd instar of S. depravata larvae was 53.3% to 66.7% 5 days later after treatment of entomopathogenic nematodes. $LC_{50}$ value of S. carpocapsae GSN1 and S. monticolum Jiri against 3rd instar of S. depravata was 6.9 and 3.9, respectively. Pathogenicity of S. carpocapsae GSN1 was different depending on larval stages, i.e., mortality of 2nd instar was the highest representing 73.3% but decreased from 3rd instar. Turf height affected pathogenicity of entomopathogenic nematodes. Mortality of 4th instar of S. depravata was 40.0% by S. carpocapsae GSN1 and 33.3% by S. monticolum Jiri, and 83.3% by fenitrothion, respectively, in the turf height of 14mm, but those were lower in 45mm. The corrected mortality of S. depravata larvae was lower at the entomopathgenic nematode plots than fenitrothion plot in the distribution field of Formica japonica. However, reduction rate of F japonica was higher in fenitrothion by 56.7% compared with 0% in S. carpocapsae GSN1 and 6.7% in S. monticolum Jiri. Turf height influenced control of S. depravate in S. carpocapsae GSN1 and fenitrothion. Control value of S. carpocapsae GSN1 was 62.2% in the turf height of 3-4cm, but not effective at all in 6-8cm and 12-14cm. However, there was not significantly different in fenitrothion plots. Forficula Scudderi was also reduced only in fenitrothion plots. Reduction rate was 100% in 3-4cm, 41.7% in 6-8cm, and 16.7% in 12-14cm, respectively.

• Korean journal of applied entomology
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• v.45 no.2 s.143
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• pp.201-209
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• 2006

Five strains of Korean entomopathogenic nematodes (EPN), steinernematids and heterorhabditids were evaluated and tried in laboratory, pot, and vegetable greenhouses for environmentally friendly control of diamondback moth (DBM), Plutella xyiostella, from 2002 to 2005. LC$_{50}$ values of five EPN strains against DBM were different depending on nematode strain and DBM instar. LC$_{50}$ value of Steinernema carpocapsae GSN1 (GSN1) was the lowest representing 2.6$\sim$3.9 infective juveniles (Ijs, 3rd stage) to 2nd to 4th instars of DBM. Pathogenicity of five effective strains against DBM was different depending on nematode strain, concentration, application times, and vegetable in pot. The most effective nematode was GSN1. Steinernema spp. was more effective than Heterorhabditis spp. against DBM. Two or three times of applications of EPN were effective regardless of nematode strain and concentration in pot. Efficacy of EPN was different depending on vegetable species. Efficacy was higher on Chinese cabbage, red mustard, and Ssamchoo than that on cabbage, kale, and leaf broccoli. Efficacy of GSN1, Steinernema GSNUS-10, Steinernema CSNUS-14, and Heterorhabditis GSNUH-1 was variable depending on nematode strain, concentration, application times, and vegetable in greenhouse experiments. GSN1 was the most effective and 100,000 infective juveniles per m$^2$(=$1\times10^9$ Ijs/ha) resulted in higher efficacy. Three times of application of nematodes led to higher control efficacy than one or two applications. Efficacy of nematodes was higher on Chinese cabbage than cabbage or kale in greenhouse.

• Journal of Soil and Groundwater Environment
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• v.14 no.4
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• pp.33-44
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• 2009

Water curtain of an underground LPG storage cavern is a facility to prevent leakage of high pressure gases, for which groundwater should flow freely towards the cavern and groundwater level also must be stably maintained. In this study, in order to evaluate qualities of seepage water and surrounding groundwater of an underground LPG storage cavern in Yeosu, 4 rounds of samplings, field measurements and laboratory analyses (February, May, August, October of 2007) were conducted. According to field measurements, pH was weak acidic to neutral but it gradually increased with time. Electrical conductivity (EC) of groundwater near a salt stack showed very high values between 10.47 and 38.50 mS/cm. Dissolved oxygen (DO) showed a very wide range of 0.20~8.74 mg/L and a mean of oxidation-reduction potential (ORP) was 159 mV, which indicated an oxidized condition. Levels of $Fe^{2+}$ and $Mn^{2+}$ were mostly less than 3 mg/L. All of seepage waters showed a Na-Cl type while only groundwater near the salt stack showed a Na-Cl type with a high total dissolved solid. The other groundwaters exhibited typical $Ca-HCO_3$ types. Levels of aerobic bacteria were mostly very high (573-39,520 CFU/mL). Based on the analyses of these hydrochemistry and biological characteristics, it is concluded that there are no particular problems in groundwater and seepage water, which not causing a trouble in the cavern operation. However, both for control of bio-clogging and for sustainable operation of the water curtain system, a regular hydrochemical and microbiological monitoring is required for the seepage water and surrounding groundwater.

• Anatomy & Biological Anthropology
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• v.31 no.4
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• pp.133-142
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• 2018

3D histology is a imaging system for the 3D structural information of cells or tissues. The synchrotron radiation propagation phase contrast micro-CT has been used in 3D imaging methods. However, the simple phase contrast micro-CT did not give sufficient micro-structural information when the specimen contains soft elements, as is the case with many biomedical tissue samples. The purpose of this study is to develop a new technique to enhance the phase contrast effect for soft tissue imaging. Experiments were performed at the imaging beam lines of Pohang Accelerator Laboratory (PAL). The biomedical tissue samples under frozen state was mounted on a computer-controlled precision stage and rotated in $0.18^{\circ}$ increments through $180^{\circ}$. An X-ray shadow of a specimen was converted into a visual image on the surface of a CdWO4 scintillator that was magnified using a microscopic objective lens(X5 or X20) before being captured with a digital CCD camera. 3-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed were performed using Amira software. In this study, We found that synchrotron phase contrast imaging of frozen tissue samples has higher contrast power for soft tissue than that of non-frozen samples. In conclusion, synchrotron radiation propagation phase contrast cryo-microCT imaging offers a promising tool for non-destructive high resolution 3D histology.