• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.937-944
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• 2010

Cu and Zn can be accumulated in plastic film house soils by long-term application of livestock manure or compost. The mobility and bioavailability of Cu and Zn accumulated in soils are strongly influenced by their chemical or geochemical species in soils. In order to assess the accumulation, mobility, and bioavailability of Cu and Zn in plastic film house soils, we determined their geochemical species using a sequential extraction, grouped into three pods: the total pool, the potentially mobil pool, and the mobil pool. Total contents of Cu and Zn, ranged from 14.9 to 53.1 mg $kg^{-1}$ for Cu and from 55.4 to 169 mg $kg^{-1}$ for Zn, lied by far below the soil contamination standards, but exhibited little accumulation compared with their geogenic concentrations. Mobile contents of Cu and Zn and their percentage of total contents were strongly affected by soil pH in addition to total contents and soil organic matter. Mobile contents of Cu, ranged from <0.01 to 1.71 mg $kg^{-1}$, showed their minimum between pH 5.0 and 6.0 and increased above pH 6.0 to 8.0. In contrast, mobile contents of Zn, varied from <0.01 to 12.4 mg $kg^{-1}$, showed their minimum above pH 7.0 and increased strongly with decreasing pH below 5.5~6.0. Potentially mobile and total contents of Cu and Zn rose with ascending soil organic matter. To assess ecological and toxic effects of Cu and Zn in soils, mobile and potentially mobile contents, as bioavailable and potentially bioavailable pools, should be considered more important than total contents.

• Korean Journal of Labor Studies
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• v.24 no.3
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• pp.109-142
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• 2018

This paper aims to analyze the Award wage system in Australia for construction workers. Considering low wages and precarious employment situation of construction workers in general, it is of advantage especially for them in Australia. Furthermore, it seems to be instructive for Korean construction workers, who stand in more precarious and unstable situation and furthermore are lack of fair wage and social safety. After strong and longstanding labour struggle in the late 19th century in Australia, it has been established a tripartite institution called as 'tribunal' between trade unions, employers, and the government. Under the highly institutionalized form of industrial relations, it functions as an arbitration and conciliation system between labour and management. The Award wage system stands in the middle point. This Award wage system including various welfare provisions is settled by the tribunal, today renamed as Fair Work Commission. In this wage system should be defined level of minimum wages according to the various skill levels, which are in turn connected with compulsory superannuation and Medicare as well as vocational education and training. Furthermore, it provides especially for the construction workers, who suffer from job instability, so-called 'portable benefits', which relate to long service leave and redundancy pay. Considering general conditions of precarious construction workers in Korea, In that respect, the Australian Award wage system would be very instructive for our social wage and safety system for construction workers.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.1-12
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• 2018

This study was conducted to analyze the openness of erosion control dams situated near mountain stream. The ecological functions of erosion control dams analyzed by such openness for adequately protect and manage the diversity of species and to prevent disasters. The obtained results were as follows. When structurally modifying or changing non-permeable, gravity type dams with a passing rate of less than 1% into open-type dams, the passing rate increased by about 77 times more from 0.72% to 55.8%. Except for closed, gravity type erosion control dams that are constructed with a special purpose such as creating sand deposits and reservoirs, there is a need to construct and improve the dams into permeable type dams that can relatively satisfactorily perform various functions such as carrying soil and sand to the downstream region and create a ecological corridor upstream and downstream for fish and amphibians. The openness based on the blocking height of the erosion control dam varies depending upon the height of the base part and the depth of the substructural part. It must be designed based on the on-site conditions and the purpose of the construction. The functional types of erosion control dams based on the open form of the cross-section as follows: the fish traffic type, flood control type, reservoir type for forest fire control), non-permeability type for soil and rock blocking, net type for blocking the rock flow and the particle screen type.

• Journal of IKEEE
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• v.22 no.4
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• pp.1025-1030
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• 2018

The proposed modulator is designed by utilizing a conventional structure employing time division technique to realize the 4th order delta-sigma modulator using one op-amp. In order to reduce the influence of KT/C noise, the capacitance in the first and second integrators reused was chosen to be 20pF and capacitance of third and fourth integrators was designed to be 1pF. The stage variable technique in the low power reconfigurable op-amp was used to solve the stability issue due to different capacitance loads for the reduction of KT/C noise. This technique enabled the proposed modulator to reduce the power consumption of 15% with respect to the conventional one. The proposed modulator was fabricated with 0.18um CMOS N-well 1 poly 6 metal process and consumes 305uW at supply voltage of 1.8V. The measurement results demonstrated that SNDR, ENOB, DR, FoM(Walden), and FoM(Schreier) were 66.3 dB, 10.6 bits, 83 dB, 98 pJ/step, and 142.8 dB at the sampling frequency of 256kHz, oversampling ratio of 128, clock frequency of 1.024 MHz, and input frequency of 250 Hz, respectively.

• Journal of Navigation and Port Research
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• v.43 no.3
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• pp.143-152
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• 2019

In this paper, the towing stability of the LNG bunker barge was estimated. Currently, LNG bunkering barge is being developed for the bunkering of LNG (Liquefied Natural Gas), an eco-friendly energy source. Since the LNG bunkering barge assumes the form of a towed ship connected to the tow line, the towing stability of the LNG bunker barge is crucial f not only for the safety of the LNG bunker barge but also the neighboring sailing vessels. In the initial stages, a numerical code for towing simulation was developed to estimate the towing stability of the LNG bunkering barge. The MMG (Maneuvering Mathematical modeling Group) model was applied to the equations of motion while the empirical formula was applied to the maneuvering coefficients for use in the initial design stage. To validate the developed numerical code, it was compared with published calculation and model test results. Towing simulations were done based on the changing skeg area and the towing position of the LNG bunkering barge using the developed numerical codes. As a result, the suitability of the designed stern skeg area was confirmed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.185-188
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• 2019

In this paper, the towing stability of the LNG bunker barge is estimated. Currently, LNG bunkering barge is being developed as an infrastructure for the bunkering of LNG (Liquefied Natural Gas), an eco-friendly energy source. Since the LNG bunker barge are in the form of towed ship connected to the tow line, the towing stability of the LNG bunker barge is very important for the safety of not only the LNG bunker barge but also the surrounding sailing vessels. The numerical code for towing simulation was developed to estimate the towing stability of the LNG bunker barge at the initial design stage. The MMG(Manoeuvring Mathematical Group) model was applied to the equations of motion and the empirical formula was applied to the maneuvering coefficients so that they could be used in the initial design stage. To validity of the developed numerical code, it was compared with published calculation and model test results. Towing simulations were carried out according to with and without stern skeg of the LNG bunker barge using the developed numerical code. Through the results of the simulations, the appropriateness of the stern skeg area designed was confirmed.

• Journal of IKEEE
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• v.23 no.1
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• pp.280-288
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• 2019

In the CR-enabled MANET, routing paths can be easily destroyed due to node mobility and channel unavailability (due to the emergence of the PU of a channel), resulting in significant overhead to maintain/recover the routing path. In this paper, network caching is actively used for route maintenance, taking into account the properties of the CR. In the proposed scheme, even if a node detects that a path becomes unavailable, it does not generate control messages to establish an alternative path. Instead, the node stores the packets in its local cache and 1) waits for a certain amount of time for the PU to disappear; 2) waits for a little longer while overhearing messages from other flow; 3) after that, the node applies local route recovery process or delay tolerant forwarding strategy. According to the simulation study using the OPNET simulator, it is shown that the proposed scheme successfully reduces the amount of control messages for path recovery and the service latency for the time-sensitive traffic by 13.8% and 45.4%, respectively, compared to the existing scheme. Nevertheless, the delivery ratio of the time-insensitive traffic is improved 14.5% in the proposed scheme.

• Journal of Navigation and Port Research
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• v.43 no.1
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• pp.23-32
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• 2019

In this paper, we proposed a multi-chain Time of Arrival (ToA) positioning method to estimate positions using all received Loran-C signals from multiple chains without constraining to a single chain. Conventionally, we have to choose only one chain among several available chains for position estimation using Loran-C. Therefore, the number of signals to be used for positioning is limited to three to five. In general, if more signals are used for positioning estimation, its performance tends to be improved in terms of accuracy and availability. To validate the proposed method for multi-chain Loran-C, we firstly carried out a static positioning test in land. By analyzing the test results, we confirmed that the proposed method works well under a multi-chain Loran-C scenario. Subsequently, another mobile positioning test was conducted on board a vessel under a practical application scenario. From this second test, we successfully demonstrated that the multi-chain ToA positioning method even in situations where the conventional single-chain Loran-C approach fails for positioning.

• Analytical Science and Technology
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• v.35 no.6
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• pp.256-266
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• 2022

It is important to determine the concentration of long-lived radionuclides (e.g., ¹²⁹I) in nuclear waste to ensure safety when handling it. To analyze nuclides in a solid sample (e.g., concrete and soil), it is essential to effectively separate and purify the nuclides of interest in the sample. This study reports the comprehensive efforts made to validate the analytical procedure for ¹²⁹I detection in solid samples, using a high-temperature combustion furnace. ¹²⁹I volatilized from the sample collected in 0.01 M HNO₃ solution with a reducing agent (e.g., NaHSO₃) and was rapidly measured by ICP-MS. Analytical conditions, such as pyrolysis temperature and types of mobile phase gas, catalyst, and trapping solution, were optimized to obtain a high recovery rate of spiked ¹²⁹I. Finally, the optimized method was applied for the simultaneous analysis of other volatile radionuclides, such as ³H and ¹⁴C. The performance test results for the optimized method confirmed that the LSC (for ³H and ¹⁴C) and ICP-MS (for ¹²⁹I) measurements, with the separation of volatile nuclides using a high-temperature combustion furnace, were reliable.

• The Korea Journal of Herbology
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• v.29 no.4
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• pp.45-52
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• 2014

Objectives : The purpose of this study was to evaluate the efficacy of HT008 on pain relief and functional improvement in participants with mild knee osteoarthritis (OA) in comparison with that of glucosamine sulfate. Methods : This randomized double-blind trial was conducted at Kyung Hee University Medical Center in Seoul where participants with knee pain for more than 6 months and degenerative osteoarthritis were enrolled. The 100 participants were received either HT008 or glucosamine sulfate 750 mg twice daily for 8 weeks and evaluated at baseline, 4 and 8 weeks after the treatment. We primarily evaluated the differences between two groups with respect to changes in the visual analogue score (VAS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score from baseline to week 8. Secondarily the difference between and within two groups with respect to changes in WOMAC stiffness and physical function score, and Lequesne Functional Severity Index (LFI) were also evaluated. Results : At week 8, treatment with HT008 resulted in a significant reduction of the VAS for pain and WOMAC pain scores compared to the glucosamine sulfate (both p=0.003). Patients receiving HT008 experienced statistically significantly greater improvements in WOMAC physical function scores and LFI (p = 0.014 and p=0.016, respectively) than glucosamine sulfate-treated group. The within-group change in WOMAC physical function and stiffness, and LFI during the 8-week intervention revealed significant improvements in HT008-treated group. Conclusions : HT008 treatment allows significant pain reduction and functional improvement compared with glucosamine sulfate. These data confirm HT008 as an effective and safe symptomatic drug for knee OA.