• Journal of Fisheries and Marine Sciences Education
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• v.22 no.3
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• pp.362-373
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• 2010

We reviewed previous studies on well-performing aquaculture facilities, rearing environment, breeding management and feed supply to find the optimal conditions of the abalone aquaculture in marine cage. The size of marine cage varied depending on local area where the abalone farms are located. The small size cage ($2.4{\times}2.4{\times}2.5$ m) was used in Wando, Jindo and Hanam area where much of the provincial's abalone production is conducted and the middle size cage ($2.4{\times}4.8{\times}2.5$ m) was used in Huksando area. Big size group, above 2 cm in shell length, was produced from the end of October to the middle of November and small size group, below 2 cm in shell length, was produced from the end of March to the beginning of April next year in case of juvenile abalone of land production. The initial stocking density was 517-1,653 individuals/culture square meter($m^2$) in case of the big size group. The optimal rearing density was 326 and 263 individuals/culture square meter ($m^2$) after 1 year and 2 year's rearing, respectively. It is shown that relationship between individual shell length (x) and rearing density (y) is estimated to be $y=2,803.1x^{-1.4641}$ ($r^2=0.9687$). In addition, The obvious relationship was indicated between number of cage (x) and sea weed production facilities (y) as y=1.1542x+10.832 ($r^2=0.918$) in Wando, because sea mustard (Undaria pinnatifida) or japanese tangle (Laminaria japonica) was supplied as a feed for abalone culture. The general pattern of relationship between shell length (x) and shell weight (y) of cultured abalone is estimated to be $y=0.1443x^{2.9461}$ ($r^2=0.9997$).

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.4
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• pp.113-126
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• 2021

This study was conducted to analyze the forest status and deforestation area changes of the DMZ region in North Korea based on satellite images. Using growing and non-growing season's RapidEye satellite images, land cover of the North Korean DMZ was classified into stocking land(conifer, deciduous, mixed), deforested land(unstocked mountain, cultivated mountain, bare mountain), and non-forest areas. Deforestation rates in the Yeonan-baecheon, Beopdong-Pyeonggang, Heoyang-Geumgang and Tongcheon-Goseong district were calculated as 14.24%, 16.75%, 5.98%, and 16.63% respectively. Forest fire and land use change of forest were considered as the main causes of deforestation of DMZ. Changes in deforestation area were analyzed through Google Earth images. As a results, it was shown that the area of deforestation was on a decreasing trend. This study can be used as basic data for establishing inter-Korean border region's forest cooperation strategies by providing forest spatial information on the North Korea's DMZ.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.189-195
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• 2013

Experiments for net cage culture at sea were conducted in each $2.4{\times}2.4$ m in area and took the samples from four different densities: 150, 300, 450 and 600 per cross-sectional area ($m^2$) of shelter. The same stocking densities applied to indoor tank culture to investigate the growth and survival rate. The size of juvenile abalone sample was $36.14{\pm}2.28$ mm for net cage culture and $38.62{\pm}3.22$ mm or indoor tank. Feed such as raw brown sea mustard, raw kelp and dried kelp was sufficiently provided to the abalone. In net cage culture experiment, the growth of the spat of juvenile abalone was the fastest $60.53{\pm}5.75$ mm in the 150 abalone cage per square meter ($m^2$), followed by the 300 abalone cage at $54.01{\pm}5.17$ mm, 450 abalone cage at $51.48{\pm}5.37$ mm and 600 abalone cage at $51.09{\pm}4.96$ mm in order. In the meantime, in the indoor tank experiment, the 150 abalone indoor tank was the fastest $47.50{\pm}6.31$ mm per square meter, followed by the 300 abalone tank at $45.92{\pm}5.23$ mm, the 450 abalone tank at $44.24{\pm}5.59$ mm and the 600 abalone tank at $43.62{\pm}4.44$ mm in order. The survival rate was more than 97.9% in all the experiments, not showing a significant difference.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.1
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• pp.168-182
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• 2019

The objectives of this study were to examine the production processes and methods of "Forest Type Map Actualization Production (Database (DB) Construction Work Manual)" (Work Manual) identify issues associated with the production processes and methods, and suggest solutions for them by applying evaluation items to a 1:5k digital forest type map. The evaluation items applied to a forest type map were divided into zoning and attributes, and the issues associated with the production processes and methods of Work Manual were derived through analyzing the characteristics of the stand structure and fragmentation by administrative districts. Korea is divided into five divisions, where one is set as the area changed naturally and the other four areas set as the area changed artificially. The area changed naturally has been updated every five years, and those changed artificially have been updated annually. The fragmentation of South Korea was analyzed in order to examine the consistency of the DB established for each region. The results showed that, in South Korea, the number of patches increased and the mean patch size decreased. As a result, the degree of fragmentation and the complexity of shapes increased. The degree of fragmentation and the complexity of shapes decreased in four regions out of 17 regions (metropolitan cities and provinces). The results indicated that there were spatial variations. The "Forest Classification" defines the minimum area of a zoning as 0.1ha. This study examined the criteria for the minimum area of a zoning by estimating the divided object (polygon unit) in a forest type map. The results of this study revealed that approximately 26% of objects were smaller than the minimum area of a zoning. The results implied that it would be necessary to establish the definition and the regeneration interval of "Areas Changed Artificially and Areas Changed Naturally", and improve the standard for the minimum area of a zoning. Among the attributes of Work Manual, "Species Change" item classifies terrain features into 52 types, and 43 types of them belong to stocking land. This study examined distribution ratios by extracting species information from the forest type map. It was found that each of 23 species, approximately 53% of species, occupied less than 0.1% of Forested land. The top three species were pine and other species. Although undergrowth on unstocked forest land are classified in the terrain feature system, their definition and classification criteria are not established in the "Forest Classification" item. Therefore, it will be needed to reestablish the terrain feature system and set the definitions of undergrowth.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.11
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• pp.1615-1634
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• 2004

A review was undertaken to obtain information on the sustainability of pig free-range production systems including the management, performance and health of pigs in the system. Modern outdoor rearing systems requires simple portable and flexible housing with low cost fencing. Local pig breeds and outdoor-adapted breeds for certain environment are generally more suitable for free-range systems. Free-range farms should be located in a low rainfall area and paddocks should be relatively flat, with light topsoil overlying free-draining subsoil with the absence of sharp stones that can cause foot damage. Huts or shelters are crucial for protecting pigs from direct sun burn and heat stress, especially when shade from trees and other facilities is not available. Pigs commonly graze on strip pastures and are rotated between paddocks. The zones of thermal comfort for the sow and piglet differ markedly; between 12-22$^{\circ}C$ for the sow and 30-37$^{\circ}C$ for piglets. Offering wallows for free-range pigs meets their behavioural requirements, and also overcomes the effects of high ambient temperatures on feed intake. Pigs can increase their evaporative heat loss via an increase in the proportion of wet skin by using a wallow, or through water drips and spray. Mud from wallows can also coat the skin of pigs, preventing sunburn. Under grazing conditions, it is difficult to control the fibre intake of pigs although a high energy, low fibre diet can be used. In some countries outdoor sows are fitted with nose rings to prevent them from uprooting the grass. This reduces nutrient leaching of the land due to less rooting. In general, free-range pigs have a higher mortality compared to intensively housed pigs. Many factors can contribute to the death of the piglet including crushing, disease, heat stress and poor nutrition. With successful management, free-range pigs can have similar production to door pigs, although the growth rate of the litters is affected by season. Piglets grow quicker indoors during the cold season compared to outdoor systems. Pigs reared outdoors show calmer behaviour. Aggressive interactions during feeding are lower compared to indoor pigs while outdoor sows are more active than indoor sows. Outdoor pigs have a higher parasite burden, which increases the nutrient requirement for maintenance and reduces their feed utilization efficiency. Parasite infections in free-range pigs also risks the image of free-range pork as a clean and safe product. Diseases can be controlled to a certain degree by grazing management. Frequent rotation is required although most farmers are keeping their pigs for a longer period before rotating. The concept of using pasture species to minimise nematode infections in grazing pigs looks promising. Plants that can be grown locally and used as part of the normal feeding regime are most likely to be acceptable to farmers, particularly organic farmers. However, one of the key concerns from the public for free-range pig production system is the impact on the environment. In the past, the pigs were held in the same paddock at a high stocking rate, which resulted in damage to the vegetation, nutrient loading in the soil, nitrate leaching and gas emission. To avoid this, outdoor pigs should be integrated in the cropping pasture system, the stock should be mobile and stocking rate related to the amount of feed given to the animals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.558-569
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• 2020

This study examined the frequency of a broiler's stay in each area as stock density using an ICT-based image analysis technique from the perspective of precision livestock farming (PLF) according to the increase in the domestic broiler farms to understand the normal behavior patterns of broilers by age. The broiler was used in the experimental box (3.3×2.7 m) in a poultry house in Gyeonggi province. The stock densities were 9.5 birds/㎡ (n=85) and 19 birds/㎡ (n=170), respectively, and the frequency of stay by feeding, water, and rest area was monitored using a top-view camera. The image data of three-colored-specific broilers identified as the stock density were acquired by age (12, 16, 22, 27, and 29 days) for six hours. In the collected image data, the object tracking technique was used to record the cumulative movement path by connecting approximately 640,000 frames at 30 fps to quantify the frequency of stay in each area. In each stock density, it was significant in the order of the rest area, feeding, and water area (p<0.001). In 9.5 birds/㎡, it was at 57.9, 24.2, and 17.9 %, and 73.2, 16.8, and 10 % in 19 birds/㎡. The frequency of a broiler's stay could be evaluated in each area as the stock density using an ICT-based image analysis technique that minimizes stress. This method is expected to be used to provide basic material for developing an ICT-based management system through real-time monitoring.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.331-339
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• 2010

Shrimp farming is the most important mariculture industry on the west coast of South Korea. However, it has suffered from mass mortality due to viral disease outbreaks and coastal pollution due to water discharge. This study developed an intensive shrimp culture method for outdoor ponds, without water exchange, which minimizes the chance of viral transmission from the environment, reduces coastal pollution by water discharge and enhances shrimp production. A culture trial was conducted in two high-density polyethylene (HDPE)-lined ponds with a $550\;m^2$ surface area. The ponds were stocked with postlarvae of Litopenaeus vannamei, the major farmed shrimp species in Korea, on July 10, 2007, and cultured for 90 days with no water exchange. The stocking density of the postlarvae (B.W. 0.0015 g) was $272\;ind./m^2$, which is eight times higher than in traditional pond culture in Korea. At harvest, the total production of ponds 1 and 2 was 1,362kg ($2.48\;kg/m^2$) and 1,282 kg ($2.33\;kg/m^2$), respectively. This is 20~22 times higher than the mean farmed shrimp production ($0.112\;kg/m^2$) in Korea and about eight times higher than in traditional ponds with a good harvest. Although there was no water exchange throughout the culture period, the mean concentrations of unionized ammonia and nitrite-nitrogen were as low as 0.038 and 6.0 mg/L, respectively. The feed conversion rate (FCR) was 1.38, which is 20~45% lower than that of traditional pond cultures. The high efficiency of the diet in this study is thought to be due to a well-managed feeding strategy and well-developed bioflocs used as diet additions for the shrimp. The final body weight of the shrimp at harvest was low (12.2~12.5 g), compared with that of traditional pond culture. This may have resulted from the combination of a short culture period, high density of shrimp, and low temperature. This study suggests that a super-intensive shrimp pond culture method using biofloc technology with no water exchange can minimize viral transmission via water exchange, reduce coastal pollution, and enhance shrimp production.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.418-428
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• 2019

The purpose of this study was to analyze and clarify the forest information shown in the Korean Peninsula Forest Distribution Map (KPFDM) printed in 1910. First, the background, process, results, and reliability of the Forest Survey Project (1910), which is the basis of the KPFDM, were evaluated. Next, the information of the KPFDM, preserved as a paper map, was digitized to show forest status and forest type. The results of the analysis can be summarized as follows: Analyzing the Korean peninsula of the 1910 period in terms of the present South and North Korean regions, stocked forests were found to be more widely distributed (73%) in the northern region. The southern region largely consisted of deforested areas, with young-growth trees and unstocked forests making up 80% of all forests there. The northern region had abundant natural forests, with 80% of the forests in Yanggang-do, which currently includes Mt. Baekdu and the Hyesan area, composed of stocked forests. Pinus densiflora was found about 2.7 times more often in the southern region than in the northern region. Large numbers of coniferous trees excluding Pinus densiflora were found in the northern region. In particular, 53% of the forests and 72% of the stocking land in the southern region were composed of Pinus densiflora.

• Journal of Aquaculture
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• v.9 no.3
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• pp.223-232
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• 1996

Growth and survival rate in shortnecked clam, Ruditapes philippinarum were studied from different seedling production areas, Hadong, Ulsan and Kochang to Kwangyang Bay, Korea, and three stocking densities (1,000, 1,500 and 3,000 individuals/$m^2$) of clam from Ulsan seedling production area were examined. During the experimental period, water temperature and specific gravity were ranged from 4.5 to $26.0^{\circ}C$ and from 1.0216 to 1.0248, respectively. Shell length was grown from $2.30{\pm}0.05\;to\;3,29{\pm}0.02$ cm in Hadong, $1.32{\pm}0.02\;to\;3.15{\pm}2.02$ cm in Ulsan, $1.24{\pm}0.03\;to\;3.18{\pm}0.02$ cm in Kochang. Kochang's seed was displayed fast growth rate than others. In different rearing densities, the lower density group was showed a rapid growth rate. Shell length from the 1,000 individuals per $m^2$ group grew longer than that from the 2,000 individuals group. Total weight from the 1,000 individuals group was higher than that from the 1,5()0 individual and the 2,000 individual groups. Survival rate by seedling production areas, Hadong, Ulsan and Kochang showed $69.4\%,\;63.8\%\;and\;41.7\%$, respectively. Survival rate by rearing density, 1,000, 1,500 and 2,000 individual groups showed $70.8\%,\;67.8\%\;and\;59.0\%$, respectively.

• Journal of Aquaculture
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• v.20 no.4
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• pp.270-277
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• 2007

White spot syndrome virus (WSSV) which is the most serious threat to cultured shrimp around the world has given enormous economic damages to shrimp culture industry every year since it was found from the shrimp ponds in the west coast of the South Korea in 1993. WSSV has strong infectivity as well as virulence and it can be rapidly transmitted among shrimps in ponds by cannibalism of infected ones. Polyculture of shrimps with carnivorous fish has been applied in commercial shrimp farms to suppress or delay the viral outbreak because the fish may selectively eat the moribund shrimps infected by virus. To determine the selective predatory effect of a carnivorous fish, river puffer Takifugu obscurus on white shrimp Litopenaeus vannamei, polyculture trials in laboratory scale of WSSV-infected and non-infected shrimps with river puffer were conducted in concrete round tanks of $28.26\;m^2$ in surface area as followings: 1) juvenile shrimps (B. W. 0.62 g) with 5 months old puffer (B. W. 11.60 g) cultured for 8 days, and 2) sub-adult shrimps (B. W. 6.84 g) with 16 months old puffer (B. W. 85.82 g) cultured for 5 days in order to know the effects according to size difference of cultured animals. In polyculture of juvenile shrimp with 5 months old puffer, survival rates of infected and non-infected shrimps were 46.0% and 89.1% respectively and in that of sub-adult shrimp with 16 months old puffer those were4% and 48% respectively. The results showed that puffer tends to selectively prey on virus infected shrimps among infected and non-infected ones in a limited space with although there is difference in predatory rate with age and density of animals. Regardless of different densities and ages of animals as well as health condition of shrimps, however, there were low differences in daily biomass of shrimp consumed per kg body weight of puffer. This finding suggests that puffer preys on healthy shrimps when moribund shrimps were not sufficient. Therefore, farmers should consider the total biomass of puffer as well as density and stocking time when they stock puffer into shrimp ponds for polyculture.