• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.2
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• pp.65-71
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• 1984

As a primary step in studying the relationship between the arrangement of netting and the section shape of the bag net in the four-seam trawling net, a series of experiments were performed with the simplified model of the bag net made of vinyl film. This model was suspended horizontally in circularly flowing water, with two pairs of suspending threads to four points of symetry at the border of the bag mouth in place of both wing nets. And then, the area distribution of each panel in the bag net was arranged by the portion of the length of the side panel, q to that of the lower or upper panel, p at the border of bag mouth. In the experiments, the section shape of the bag mouth photographed and the tensions on both pairs of suspending threads were measured with two loadcells in circularly flowing water. From the results that the section shape of the bag mouth in circularly flowing water is controlled by the area distribution of panels in the bag net, the author estimated an experimental equation. h/w=k sub(1) e super(k) 2 super(q/p)+C, where h is the central height of the bag mouth, and w is the lateral width of that.

• Journal of Internet Computing and Services
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• v.24 no.5
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• pp.1-7
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• 2023

This paper proposes a small cell resource partitioning allocation method to solve interference to machine type communication devices (MTCD) and improve performance in 5G heterogeneous networks (HetNet) where macro base station (MBS) and many small cell base stations (SBS) are overlaid. In the 5G HetNet, since various types of MTCDs generate data traffic, the load on the MBS increases. Therefore, in order to reduce the MBS load, a cell range expansion (CRE) method is applied in which a bias value is added to the received signal strength from the SBS and MTCDs satisfying the condition is connected to the SBS. More MTCDs connecting to the SBS through the CRE will reduce the load on the MBS, but performance of MTCDs will degrade due to interference, so a method to solve this problem is needed. The proposed small cell resource partitioning allocation method allocates resources with less interference from the MBS to mitigate interference of MTCDs newly added in the SBS with CRE, and improve the overall MTCD performace using separating resources according to the performance of existing MTCDs in the SBS. Through simulation results, the proposed small cell resource partitioning allocation method shows performance improvement of 21% and 126% in MTCDs capacity connected to MBS and SBS respectively, compared to the existing resource allocation methods.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.4
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• pp.101-114
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• 2022

Recently, various studies on the entrepreneurial ecosystem have been conducted. The entrepreneurial ecosystem is composed of various elements such as entrepreneurs, governments, and infrastructure, and these factors interact to contribute to economic development. The purpose of this study was to analyze differences in importance and performance of the entrepreneurial ecosystem for startups using the importance-performance analysis (IPA) method. Based on this, the importance and current level of the components of the entrepreneurial ecosystem were identified and policy implications were presented. The results of the study are as follows. The importance ranking was in the order of startup support program(4.43), startup funding (4.39), market accessibility(4.30). The ranking of performance was startup support program(3.81), ease of starting a business(3.76), support for startup support institutions(3.66), and startup funding(3.66). All elements of the entrepreneurial ecosystem showed higher importance than performance. This means that the components of the entrepreneurial ecosystem in Korea are recognized as important, but do not play a significant role in terms of performance for startups. In addition, the factors with the highest improvement in the importance-performance matrix were 「safety nets for startup failure」, 「culture of acceptance of failure」, 「ease of market entry」, 「ease of startup survival」, and 「ease of exit」. This study suggested improvement measures such as establishing a social safety net, improving awareness of startup failure culture, matching successful startups, strengthening scale-up support by growth stage, easing regulations in new business fields, and diversifying investment recovery strategies.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.2
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• pp.121-124
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• 2007

Freshwater-adapted maturing chum salmon (Oncorhynchus keta) involuntarily captured by stationary nets in Yang-yang seashore areas were transferred to freshwater in an outdoor raceway tank at Yeongdong Inland Fisheries Research Institute, NFRDI, Yang-yang, Gangwon, Korea and kept over 1 day until the start of the experiments. The freshwater-adapted females were single-injected intraperitoneally with gonadotropin-releasing hormone analogue, (GnRH-a: $70\;{\mu}g/kg$ body weight, BW) alone or combined with a dopamine receptor antagonist, pimozide($700\;{\mu}g/kg$ BW). Although gonadosomatic indices [GSI, (gonad weight/BW)${\times}100$] did not show significant changes in both 2004 and 2005, GSI of GnRH-a-injected fish during the 2005 trial slightly increased on the 5th and 7th days post-injection compared to those of vehicle treated fish. Hepatosomatic indices [HSI, (liver weight/BW)${\times}100$] of fish injected with GnRH-a alone and combined with pimozide decreased significantly on the 7th day post-injection in 2004(P<0.05). In 2005 trials, HSI was significantly reduced in GnRH-a treated fish on the 7th day post-injection (P<0.05). Pimozide-injected fish showed a pattern with increase of GSI and decrease of HSI, without significant differences. Taken together, these results suggest that at least in part hypothalamic hormones and dopamine receptor antagonist may induce sexual maturation in freshwater-adapted maturing chum salmon. It remains to evaluate these preliminary results by further researches.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.341-349
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• 2023

Gamcheon Port, which is one of three major harbors in the Port of Busan, is being operated to load, discharge and transport a wide range of cargoes, including general cargo, fisheries, steel products, cement, etc,. The harbor, designated as a compulsory pilotage area, provides pilotage services in compliance with relevant laws and regulations for arrival and departure of vessels in the Gamcheon Port area. Some academic research on the marine traffic environment in Gamcheon Port has been conducted. However, the pilotage environment and hazards to pilotage safety in the port have yet to be studied. Therefore, in this research, the pilotage environment and hazards to pilotage safety were identified, and it was confirmed that there are hazards to pilotage safety, such as vessels installed poor facilities including damaged pilot boarding arrangements, vessels blocking pilot's view by her structures and fishing nets, vessels unable to communicate in English, vessels not following VTS's order. The hazards to pilotage safety were also stratified, and the importance of the hazards was verified in accordance with a survey based on Analytic Hierachy P rocess(AHP) for Busan Harbor pilots, and safety measures to secure pilotage safety were examined to secure the safety of vessels calling Gamcheon Port.

• Korean Journal of Radiology
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• v.25 no.4
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• pp.363-373
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• 2024

Objective: To develop and evaluate a deep learning model for automated segmentation and detection of bone metastasis on spinal MRI. Materials and Methods: We included whole spine MRI scans of adult patients with bone metastasis: 662 MRI series from 302 patients (63.5 ± 11.5 years; male:female, 151:151) from three study centers obtained between January 2015 and August 2021 for training and internal testing (random split into 536 and 126 series, respectively) and 49 MRI series from 20 patients (65.9 ± 11.5 years; male:female, 11:9) from another center obtained between January 2018 and August 2020 for external testing. Three sagittal MRI sequences, including non-contrast T1-weighted image (T1), contrast-enhanced T1-weighted Dixon fat-only image (FO), and contrast-enhanced fat-suppressed T1-weighted image (CE), were used. Seven models trained using the 2D and 3D U-Nets were developed with different combinations (T1, FO, CE, T1 + FO, T1 + CE, FO + CE, and T1 + FO + CE). The segmentation performance was evaluated using Dice coefficient, pixel-wise recall, and pixel-wise precision. The detection performance was analyzed using per-lesion sensitivity and a free-response receiver operating characteristic curve. The performance of the model was compared with that of five radiologists using the external test set. Results: The 2D U-Net T1 + CE model exhibited superior segmentation performance in the external test compared to the other models, with a Dice coefficient of 0.699 and pixel-wise recall of 0.653. The T1 + CE model achieved per-lesion sensitivities of 0.828 (497/600) and 0.857 (150/175) for metastases in the internal and external tests, respectively. The radiologists demonstrated a mean per-lesion sensitivity of 0.746 and a mean per-lesion positive predictive value of 0.701 in the external test. Conclusion: The deep learning models proposed for automated segmentation and detection of bone metastases on spinal MRI demonstrated high diagnostic performance.

• Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.240-255
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• 2024

Widas Reservoir is situated in an area of 570 ha in the Pajaran Village, Madiun Regency, East Java Province, Indonesia, playing an essential role in fisheries, with the average fish catch per year of about 283 tons/year. This study explores the standing stock, growth parameters, mortality, and exploitation rates of several dominant fishes in Widas Reservoir. This study was carried out from February to November 2019. Fish stocks were estimated using acoustic tools, fish catch records, and sizes collected by local enumerators. Fish length frequency sampling was conducted on several dominant fish species, such as Oreochromis niloticus, Barbonymus gonionotus, and Osteochilus vittatus. Based on the length-frequency data, estimating fish population dynamics, the fish population dynamics (infinitive length (L_∞) and growth coefficient (K)) estimation was run in a time series using the Fish Sock Analysis Tool, II (FISAT II) program package. Moreover, the estimation of natural mortality parameters, the fishing mortality parameter, and the exploitation rate was also performed. The approximated overall fish stock in the Widas Reservoir was about 79,848 kg, which lowered with the increase in water depth. Of particular concern, in the surface layer at a depth between 1-5 m, the fish stock reached 58,813 kg, while in the deeper zone (> 15 m), the value significantly lowered by about 98%, reaching 1,219 kg. These results indicate an overfishing in the Widas Reservoir. The value of the exploitation rate (E) of B. gonionotus was 0.748, O. niloticus 0.8, and O. vittatus 0.7, respectively, proving the overfishing states occurred in the study area. Therefore, regulations governing the number of catches and the use of fishing gear are crucial in Widas Reservoir, particularly the use of lift and gill nets with a mesh size of less than 2 cm.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.9 no.1
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• pp.1-18
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• 1973

For regulating the depth of midwater trawl nets towed at the optimum constant speed, the changes in the shape of warps caused by adding a weight on an arbitrary point of the warp of catenary shape is studied. The shape of a warp may be approximated by a catenary. The resultant inferences under this assumption were experimented. Accordingly feasibilities for the application of the result of this study to the midwater trawl nets were also discussed. A series of experiments for basic midwater trawl gear models in water tank and a couple of experiments of a commercial scale gears at sea which involve the properly designed depth control devices having a variable attitude horizontal wing were carried out. The results are summarized as follows: 1. According to the dimension analysis the depth y of a midwater trawl net is introduced by $$y=kLf(\frac{W_r}{R_r},\;\frac{W_o}{R_o},\;\frac{W_n}{R_n})$$) where k is a constant, L the warp length, f the function, and $W_r,\;W_o$ and $W_n$ the apparent weights of warp, otter board and the net, respectively, 2. When a boat is towing a body of apparent weight $W_n$ and its drag $D_n$ by means of a warp whose length L and apparent weight $W_r$ per unit length, the depth y of the body is given by the following equation, provided that the shape of a warp is a catenary and drag of the warp is neglected in comparison with the drag of the body: $$y=\frac{1}{W_r}\{\sqrt{{D_n^2}+{(W_n+W_rL)^2}}-\sqrt{{D_n^2+W_n}^2\}$$ 3. The changes ${\Delta}y$ of the depth of the midwater trawl net caused by changing the warp length or adding a weight ${\Delta}W_n$_n to the net, are given by the following equations: $${\Delta}y{\approx}\frac{W_n+W_{r}L}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}{\Delta}L$$ $${\Delta}y{\approx}\frac{1}{W_r}\{\frac{W_n+W_rL}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}-{\frac{W_n}{\sqrt{D_n^2+W_n^2}}\}{\Delta}W_n$$ 4. A change ${\Delta}y$ of the depth of the midwater trawl net by adding a weight $W_s$ to an arbitrary point of the warp takes an equation of the form $${\Delta}y=\frac{1}{W_r}\{(T_{ur}'-T_{ur})-T_u'-T_u)\}$$ Where $$T_{ur}^l=\sqrt{T_u^2+(W_s+W_{r}L)^2+2T_u(W_s+W_{r}L)sin{\theta}_u$$ $$T_{ur}=\sqrt{T_u^2+(W_{r}L)^2+2T_uW_{r}L\;sin{\theta}_u$$ $$T_{u}^l=\sqrt{T_u^2+W_s^2+2T_uW_{s}\;sin{\theta}_u$$ and $T_u$ represents the tension at the point on the warp, ${\theta}_u$ the angle between the direction of $T_u$ and horizontal axis, $T_u^2$ the tension at that point when a weights $W_s$ adds to the point where $T_u$ is acted on. 5. If otter boards were constructed lighter and adequate weights were added at their bottom to stabilize them, even they were the same shapes as those of bottom trawls, they were definitely applicable to the midwater trawl gears as the result of the experiments. 6. As the results of water tank tests the relationship between net height of H cm velocity of v m/sec, and that between hydrodynamic resistance of R kg and the velocity of a model net as shown in figure 6 are respectively given by $$H=8+\frac{10}{0.4+v}$$ $$R=3+9v^2$$ 7. It was found that the cross-wing type depth control devices were more stable in operation than that of the H-wing type as the results of the experiments at sea. 8. The hydrodynamic resistance of the net gear in midwater trawling is so large, and regarded as nearly the drag, that sweeping depth of the gear was very stable in spite of types of the depth control devices. 9. An area of the horizontal wing of the H-wing type depth control device was $1.2{\times}2.4m^2$. A midwater trawl net of 2 ton hydrodynamic resistance was connected to the devices and towed with the velocity of 2.3 kts. Under these conditions the depth change of about 20m of the trawl net was obtained by controlling an angle or attack of $30^{\circ}$.

• Journal of the Economic Geographical Society of Korea
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• v.8 no.1
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• pp.153-169
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• 2005

In this study, we analysed the state of the fisheries in Chungnam around 1910 from Hangook Susanji. As a result, there were about 30 ports in the west coast area in Chungnam, and we can classify their locations into 5 types Type I is located in small and mid sized rivers. Type II is located in a costal port. Type III is ports facing the open sea, and type IV is ports in a bay. Type V is ports on islands of coast. Species of fish are porges, mackerels, sting rays, croakers, hairtails, shrimps, etc. The base of fishing porge was Jukdo and Yeondo. The fishing banks of croakers are formed from Chilsantan, Jeonlado to the area of seashore, Chungnam. Hairtails were caught near all the areas of seashore. Salt manufacturing is done near all coasts of Chungnam, Seocheon-bay, Ungcheon-bay, Ocheon-bay, Anmyeon island, Taean, Dangjin area, etc represent this work. Especially, the salt which was produced in Taeangun was so famous that it was called ' Taeansalt'. In the Kum-river area there were 32 fishing villages. Freshwater fish were caught in the upper stream area and the mouth of Geumgang, down stream, was the center for producing Baengeo. There were 23 fishing villages, and the species consisted of croaker, hairtail, Forge, gray mullet, sting ray, sharks, anchovy, shrimps, etc in Biin-bay. The coast of Boryeong had about 33 fishing villages, but their fishing industry was not developed more than their good salt manufacturing. Though there are records that Chunsu-bay had 28 fishing villages, Taean peninsula and Garolim-bay had about 70 fishing villages, and Asan-bay area had about 55 fishing villages, they were developed a little, but not more than Weir fisheries or salt manufacture on the base of salt area and the tideland because these areas were just for farming. South of Anmyeon island of West coast island areas is the biggest area of Stow nets on stakes fishing and the island areas down mouth of Kum river were centers for producing porge.

• Korean Journal of Plant Resources
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• v.9 no.2
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• pp.151-155
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• 1996

For improvement germination rate of Cirsium setidens, wet seeds were storaged for 20 to 80 days at $4^{\circ}C$ and germinated at $18^{\circ}C$ in the dark or light condition. To assess the effects of shading and plant age on the growth, fresh yield and seed yield under rain shelter in highland at altitude of 800m above sea level, seeds were sown in an open field in late september,1990. In early May the next the seedlings were transplanted for vegetatable and seed production in the plastic houses for rain shelter. They were grown from 1991 to 1993 in the houses covered with the shading nets ranging from 0 to 70% for vegetable production and 0 to 50% for seed production. Germination rate inceased as the storage period lengthened, and the rate came to $60\sim80%$ at 60days after germination. It was more effective in lighting than in darkness. For vegetable production, the shading net treatments showed more values in almost the characters checked at the third year than the non-shading treatment. No. of stem, no, of leaves, stem length and degree of softening were no different between shading net treatments, but the other characters were significantly different. Ratio of survival, density of chlorophyll and ratio of dry matter of plants were highest in the plots of 50%, 70%, and 30% of shading, respectively. The highest fresh yield was recorded from 2-year plants, 70% of shading from them showed the greatest yield. The highest seed yields were produced 2-year-old plants of non-shading plot. For seed production, the non-shading treatment is best, and the highest seed yields were obtained in both the second and third years.