• Journal of Korean Society of Forest Science
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• v.109 no.3
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• pp.249-258
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• 2020

The purpose of this study examined the succession by vegetation type after forest ecosystem restoration in the Baramjae area. Vegetation of the Baramjae area was classified using a survey of 81 sites from May to October 2019. The vegetation type was classified as Pinus densiflora community group with both Quercus mongolica community and P. densiflora typical community. The group unit was further classified as the Quercus dentata typical subgroup, Salix koreensis subgroup, and Q. mongolica typical subgroup. Such as Q. mongolica, Quercus variavilis in vegetation unit 1, Q. mongolica, Q. dentata in vegetation unit 2, P. densiflora in vegetation unit 3 and S. koreensis in vegetation unit 4 were shown a high importance value. The difference in species by vertical layer is explained by sere. Based on the vegetation type classification system, Detrended Correspondence Analysis was conducted to observe the trend of succession. Since restoration, vegetation unit 1 and vegetation unit 2 were considered to have developed the most extensive vegetation. In vegetation unit 2 and vegetation unit 4, many of the species found were in the early vegetation development in S. koreensis subgroup. Accordingly, vegetation in the Baramjae area can be categorized as a stepwise succession.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2783-2790
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• 2010

In this paper, we first review LDPC codes in general and a belief propagation algorithm that works in logarithm domain. LDPC codes, which is chosen 802.11n for wireless local access network(WLAN) standard, require a large number of computation due to large size of coded block and iteration. Therefore, we presented three kinds of low computational algorithms for LDPC codes. First, sequential decoding with partial group is proposed. It has the same H/W complexity, and fewer number of iterations are required with the same performance in comparison with conventional decoder algorithm. Secondly, we have apply early stop algorithm. This method reduces number of unnecessary iterations. Third, early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Through the simulation, we knew that the iteration number are reduced by half using subset algorithm and early stop algorithm is reduced more than one iteration and computational complexity of early detected method is about 30% offs in case of check node update, 94% offs in case of check node update compared to conventional scheme. The LDPC decoder have been implemented in Xilinx System Generator and targeted to a Xilinx Virtx5-xc5vlx155t FPGA. When three algorithms are used, amount of device is about 45% off and the decoding speed is about two times faster than convectional scheme.

• Korean Journal of Environment and Ecology
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• v.31 no.1
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• pp.88-92
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• 2017

This study investigated the growth and maturation of free conchocelis of Pyropia yezoensis under monochromatic light of blue light(480 nm), green light(550 nm), yellow light(600 nm) and red light(730 nm) which measured the colony diameter, content of chlorophyll a and conchosporangium formation. In the result, the most of colony diameter and chlorophyll a showed under the blue light, $2,472.6{\pm}27.0{\mu}m$ and $1.55{\pm}0.03mg\;g.dw^{-1}$. Also, the chlrophyll a content of conchocelis was under the blue light. Therefore, the blue light might be favorable for the growth and maturation of conchocelis of P. yezoensis. This study will lead development of indoor culture technologies.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.16-27
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• 2017

IEEE 802.15.6 standard, a Wireless Body Area Network, aims to transfer not only medical data but also non-medical data, such as physical activity, streaming, multimedia game, living information, and entertainment. Services which transfer those data have very various data rates, intervals and frequencies of continuous access to a medium. Therefore, an efficient anti-collision operations and medium assigning operation have to be carried out when multiple nodes with different data rates are accessing shared medium. IEEE 802.15.6 standard for CSMA/CA medium access control method distributes access to the shared medium, transmits a control packet to avoid collision and checks status of the channel. This method is energy inefficient and causes overhead. These disadvantages conflict with the low power, low cost calculation requirement of wireless body area network, shall minimize such overhead for efficient wireless body area network operations. Therefore, in this paper, we propose a medium access scheduling scheme, which adjusts the time interval for accessing to the shared transmission medium according to the amount of data for generating respective sensor node, and a priority control algorithm, which temporarily adjusts the priority of the sensor node that causes transmission concession due to the data priority until next successful transmission to ensure fairness.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.69-78
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• 2011

A large-scale sensor network usually operates in open and unattended environments, hence individual sensor node is vulnerable to various attacks. Therefore, malicious attackers can physically capture sensor nodes and inject false reports into the network easily through compromised nodes. These false reports are forwarded to the base station. The false report injection attack causes not only false alarms, but also the depletion of the restricted energy resources in a battery powered network. The statistical en-route filtering (SEF) mechanism was proposed to detect and drop false reports en route. In SEF, the choice of routing paths largely affect the energy consumption rate and the detecting power of the false report. To sustain the secure routing path, when and how to execute the path re-selection is greatly need by reason of the frequent network topology change and the nodes's limitations. In this paper, the regional path re-selection period determination method is proposed for efficient usage of the limited energy resource. A fuzzy logic system is exploited in order to dynamically determine the path re-selection period and compose the routing path. The simulation results show that up to 50% of the energy is saved by applying the proposed method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.10
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• pp.1418-1424
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• 2010

This study was performed to assess the antioxidant activities and whitening effects of Sorbus commixta HEDL cortex on melanin synthesis. The whitening effects of Sorbus commixta HEDL cortex water extracts were examined by in vitro mushroom tyrosinase assay and B16BL6 melanoma cells. We assessed inhibitory effects of Sorbus commixta HEDL cortex water extracts on expression of melanogenic enzyme proteins including tyrosinase, tyrosinase-related protein 1 (TRP-1) and tyrosinase-related protein 2 (TRP-2) in B16BL6 cells. Inhibitory effects of Sorbus commixta HEDL cortex onto free radical generation were determined by measuring DPPH and hydroxyl radical scavenging activities. Our results indicated that Sorbus commixta HEDL cortex water extracts effectively inhibited free radical generation. In DPPH radical scavenging activity, Sorbus commixta HEDL cortex water extracts had a potent anti-oxidant activity in a dose-dependent manner. They significantly inhibited tyrosinase activity in vitro and in B16BL6 melanoma cells. Also, Sorbus commixta HEDL cortex suppressed the expression of tyrosinase, TRP-1 and TRP-2 in B16BL6 melanoma cells. These results show that Sorbus commixta HEDL cortex inhibited melanin production on the melanogenesis. The underlying mechanism of Sorbus commixta HEDL cortex on whitening activity may be due to the inhibition of tyrosinase activity and tyrosinase, TRP-1, TRP-2 expression. We suggest that Sorbus commixta HEDL cortex may be contain new natural active ingredients for antioxidant and whitening cosmetics.

• Journal of Soil and Groundwater Environment
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• v.14 no.3
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• pp.32-39
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• 2009

This study was conducted in order to get the scientific background for soil pollution criteria. The 92 soil samples derived from various geological units were taken and analyzed to survey natural heavy metal background levels using aqua regia digestion method and 0.1N HCl extraction method. From these results, the average natural contents of metals were 0.287 mg/kg for Cd, 15.26 mg/kg for Cu, 18.43 mg/kg for Pb, 25.36 mg/kg for Cr, 54.27 mg/kg for Zn, 17.68 mg/kg for Ni, 6.83 mg/kg for As by the aqua regia method, and 0.040 mg/kg for Cd, 0.48 mg/kg for Cu, 3.06 mg/kg for Pb, 0.09 mg/kg for Cr, 1.54 mg/kg for Zn, 0.27 mg/kg for Ni, 0.089 mg/kg for As by the 0.1N HCl extraction method. Ratios of soluble contents and total contents were Cd 0.14, Cu 0.03, Pb 0.17, Cr 0.004, Zn 0.03, Ni 0.02, As 0.013 and the correlation coefficients of soluble contents and total contents were 0.24(As), 0.88(Cd), 0.43(Cr), 0.65(Cu), 0.70(Pb), 0.61(Ni), 0.24(Zn). The correlation factor decreased in the order of Cd > Pb > Cu > Ni > Cr > Zn $\approx$ As.

• Korean Journal of Plant Resources
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• v.34 no.2
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• pp.144-155
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• 2021

This study was conducted to analyze community structure and species composition of Abies koreana forest. Field survey was carried out from June, 2019 to 2020, September. 121 plots (20×20 m) were set up, 5 herb layer plots (3×3 m) were constructed for each plot, and there, Diameter at Breast Height(DBH), height, environmental factor were measured. It was analyzed that water stress did not have a significant effect on the factors affecting the growth of A. koreana in Mt. Halla-san, and in the case of Mt. Deokyu-san, the more forest stands located at the ridge, the higher the tree density. It was found that the factors affecting the distribution of Abies koreana were not consistent according to the environment of study site.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.550-556
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• 2021

The scissor-type rope cutter is the most widely used amongst all kinds of commercially available rope cutters in Korea. In this study, we performed finite element analysis on the scissor-type rope cutter. We determined the structure of the cutter that would ensure its stable operation in various situations involving rope entanglement, and verified its effectiveness by testing it in the lab and in an actual ship. These investigations revealed that when the propeller shaft was not rotated by rope entanglement, the constant torque generated by the engine resulted in the torsion of the rope cutter and maximum deformation in the lower blade, which was not restricted by finite element analysis. With increasing blade thickness, the maximum values of deformation and equivalent stress decreased, resulting in a rise in the safety factor. At the constant blade thickness, the effect of the torque variations on the maximum equivalent stress and the maximum deformation is independent of the position of the external force of the rope cutter and decreases in direct proportion. The results of this study confirmed that the rope-cutter structure determined by analysis could lead to a hassle-free removal of ropes and fishing nets under all conditions and environments.

• Journal of the Korea Convergence Society
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• v.12 no.11
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• pp.411-418
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• 2021

The purpose of this study was to identify contents of Taekwon and to improve specialized knowledges and practical abilities for Taekwondo majoring university students. The sample was categorized into college and student. The first round survey was divided into two parts in finding possible ways to improve practical abilities from students and school authority perspectives. The second round was conducted through survey by dividing respondents into students and school authority. The third round was performed to identify the nessessities and problems in relation to specialized knowledge and practical abilities such as sparring, poomsae, and demonstration. Based on the findings, three critical themes were identified: motivating them to accumulate specialized knowledge, providing opportunities to practice, and offering diverse job directions. Students indicated several critical themes such as recognition of job opportunities in different domains, endeavour to increase communication ability with others in different domains, reconsideration to learn things in different domains, and efforts to take an interests in life-time Taekwondo. The findings provide ideas in applying practical knowledge into the field and in changing students' perception in terms of Taekwondo majoring. They are specialized knowledge and practical ability improvement based upon college authority and students (15 college authority items, 9 student items).