• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.13-25
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• 2012

Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. However, since electromechanical sensors such as strain gauge and V/W type load cell are also subject to long-term risk as well as suffering from noise during long distance transmission and immunity to electromagnetic interference (EMI), optical FBG sensors embedded tendon was developed to measure strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measuring the short-term anchor force. But to adopt this tendon to long-term monitoring, temperature compensation of the FBG sensors embedded tendon should be done. In this paper, we described how to compensate the effect in compliance with the change of underground temperature during long-term tension force monitoring of ground anchors by using optical fiber sensors (FBG: Fiber Bragg Grating). The model test was carried out to determine the temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon. The determined temperature sensitivity coefficient ${\beta}^{\prime}=2.0{\times}10^{-5}/^{\circ}C$ was verified by comparing the ground temperatures predicted from the proposed sensor using ${\beta}^{\prime}$ with ground temperatures measured from ground thermometer. Finally, temperature compensations were carried out based on ${\beta}^{\prime}$ value and ground temperature measurement from KMA for the tension force monitoring results of tension type and compression type anchors, which had been installed more than 1 year before at the test site. Temperature compensated tension forces are compared with those measured from conventional load cell during the same measuring time. Test results show that determined temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon is valid and proposed temperature compensation method is also appropriate from the fact that the temperature compensated tension forces are not dependent on the change of ground temperature and are consistent with the tension forces measured from the conventional load cell.

• Journal of Aquaculture
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• v.19 no.3
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• pp.210-215
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• 2006

An experiment was conducted to investigate the effects of four water temperatures (10, 15, 20, and $25^{\circ}C$) in combination with three photoperiods (24L:0D, 12L: 12D, and OL:24D) on the oxygen consumption rate of juvenile dark-banded rockfish, Sebastes inermis (mean body weight $20.5{\pm}0.7g$). The oxygen consumption rates of S. inermis were measured in triplicate for 24 hours using a continuous flow-through respirometer. Different combinations of water temperatures and photoperiods resulted in significant differences in the mean oxygen consumption rate of S. inermis (P<0.001). The oxygen consumption increased with increasing water temperatures for all photoperiod treatments (P<0.01). Mean oxygen consumption rates at 10, 15,20 and $25^{\circ}C$ ranged $178.3\sim283.5,\;386.7\sim530.7,\;529.2\sim754.3$ and $590.0\sim785.5mg\;O_2kg^{-1}h^{-1}$, respectively. $Q_{10}$ values ranged $3.17\sim5.51$ between 10 and $15^{\circ}C,\;1.87\sim2.10$ between 15 and $20^{\circ}C$ and $1.08\siml.24$ between 20 and $25^{\circ}C$, respectively. Fish held in continuous darkness (OL:24D) used consistently less okygen than fish exposed to continuous light (P<0.05). The mean oxygen consumption offish in a 12L:12D photoperiod was higher than that offish in 24L:0D and 0L:24D photoperiods under all temperature treatments except $10^{\circ}C$. The oxygen consumption of fish exposed to the 12L:12D photoperiod was significantly higher during the light phase than during the dark phase under all temperature treatments except $10^{\circ}C\;(P<0.05)$. This study provides empirical data for estimating oxygen consumption of S. inermis under given condition. This result has application for culture management and bioenergetic model for growth of this species.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.789-797
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• 2021

The worldwide sizes of container ships are rapidly increasing. The container ship size in 2005, which was about 9,200 TEU has increased to 24,000 TEU in recent times. In addition to the increase in the sizes of the container ships, the arrivals/departures of large container vessels to/from Korea have also increased. Hence, the necessity for reviewing safe passage of such vessels is emphasized. In the present study, a 24,000 TEU container vessel was used as a model ship to calculate the under-keel clearance (UKC) at Gadeok Channel through which vessels must pass to arrive at Busan New Port, in accordance with the Korean Port and Fishing Port Design Standards and Commentary. In addition, the maximum allowable speed that meets UKC standards was calculated using various squat formulas, whose results were then compared with the current speed limit standards. The analysis results show that Busan New Port requires 10% marginal water depth, and the squat that meets this requirement is 0.95 m. Gadeok Channel requires 15% marginal water depth, and the squat that meets this requirement is 1.78 m; in this case, the maximum allowable speed is calculated as 15 kts. Busan New Port has set the speed limit as 12 kts, which is higher than the calculated 11 kts. Thus, speed limit reconsideration is required in terms of safety. However, the set speed limit for Gadeok Channel is 12 kts, which is lower than the calculated 15 kts. Thus, additional considerations may be provided to increase the speed limits for smooth navigational passage of vessels. The present study, however, is constrained by the fact that it reflects only a limited number of elements in the UKC and allowable speed calculations; therefore, more accurate UKC and safe speed values can be suggested based on extended studies to this research.

• Maritime Security
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• v.1 no.1
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• pp.273-310
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• 2020

This study aims at empirically analyzing the overall mechanism of the "Gray Zone Strategy", which has begun to be used as one of Chinese major maritime security strategies in maritime conflicts surrounding the South China Sea and East China Sea since early 2010, and comparing the resulting conflict patterns in those reg ions. To this end, I made the following two hypotheses about Chinese gray zone strategy. The hypotheses that I have argued in this study are the first, "The marine gray zone strategy used by China shows different structures of implementation in the South China Sea and the East China Sea, which are major conflict areas.", the second, "Therefore, the patterns of disputes in the South China Sea and the East China Sea also show a difference." In order to examine this, I will classify Chinese gray zone strategy mechanisms multi-dimensionally in large order, 1) conflict trends and frequency of strategy execution, 2) types and strengths of strategy, 3) actors of strategy execution, and 4) response methods of counterparts. So, I tried to collect data related to this based on quantitative modeling to test these. After that, about 10 years of data pertaining to this topic were processed, and a research model was designed with a new categorization and operational definition of gray zone strategies. Based on this, I was able to successfully test all the hypotheses by successfully comparing the comprehensive mechanisms of the gray zone strategy used by China and the conflict patterns between the South China Sea and the East China Sea. In the conclusion, the verified results were rementioned with emphasizing the need to overcome the security vulnerabilities in East Asia that could be caused by China's marine gray zone strategy. This study, which has never been attempted so far, is of great significance in that it clarified the intrinsic structure in which China's gray zone strategy was implemented using empirical case studies, and the correlation between this and maritime conflict patterns was investigated.

• Journal of the Korean earth science society
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• v.24 no.3
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• pp.205-215
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• 2003

A precise and dense Bouguer anomaly is one of the most important data to improve the knowledge of our environment in the aspect of geophysics and physical geodesy. Besides the precise absolute gravity station net, we should consider two parts; one is to improve the precision in gravity measurement and correction of it, and the other is the density of measurement both in number and distribution. For the precise positioning, we have tested how we could use the GPS properly in gravity measurement, and deduced that the GPS measurement for 5 minutes would be effective when we used DGPS with two geodetic GPS receivers and the baseline was shorter than 40km. In this case we should use a precise geoid model such as PNU95. By applying this method, we are able to reduce the cost, time, and number of surveyors, furthermore we also get the benefit of improving in quality. Two kind of computer programs were developed to correct crossover errors and to calculate terrain effects more precisely. The repeated measurements on the same stations in gravity surveying are helpful not only to correct the drifts of spring but also to approach the results statistically by applying network adjustment. So we can find out the blunders of various causes easily and also able to estimate the quality of the measurements. The recent developments in computer technology, digital elevation data, and precise positioning also stimulate us to improve the Bouguer anomaly by more precise terrain correction. The gravity data of various sources, such as land gravity data (by Choi, NGI, etc.), marine gravity data (by NORI), Bouguer anomaly map of North Korea, Japanese gravity data, altimetry satellite data, and EGM96 geopotential model, were collected and processed to get a precise and dense Bouguer anomaly in and around the Korean Peninsula.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.9-18
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• 2024

The importance of active sonar systems is emerging due to the quietness of underwater targets and the increase in ambient noise due to the increase in maritime traffic. However, the low signal-to-noise ratio of the echo signal due to multipath propagation of the signal, various clutter, ambient noise and reverberation makes it difficult to identify underwater targets using active sonar. Attempts have been made to apply data-based methods such as machine learning or deep learning to improve the performance of underwater target recognition systems, but it is difficult to collect enough data for training due to the nature of sonar datasets. Methods based on mathematical modeling have been mainly used to compensate for insufficient active sonar data. However, methodologies based on mathematical modeling have limitations in accurately simulating complex underwater phenomena. Therefore, in this paper, we propose a sonar signal synthesis method based on a deep neural network. In order to apply the neural network model to the field of sonar signal synthesis, the proposed method appropriately corrects the attention-based encoder and decoder to the sonar signal, which is the main module of the Tacotron model mainly used in the field of speech synthesis. It is possible to synthesize a signal more similar to the actual signal by training the proposed model using the dataset collected by arranging a simulated target in an actual marine environment. In order to verify the performance of the proposed method, Perceptual evaluation of audio quality test was conducted and within score difference -2.3 was shown compared to actual signal in a total of four different environments. These results prove that the active sonar signal generated by the proposed method approximates the actual signal.

• Journal of Life Science
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• v.22 no.7
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• pp.863-870
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• 2012

Rhodopsin, a dim light photoreceptor, has been regarded as one of the model systems for the structural and functional study of G protein-coupled receptors (GPCRs). Constitutively active mutant GPCRs leading to the activation of heterotrimeric GDP/GTP-binding protein signaling in the absence of ligand binding are of interest for the study of the activation mechanism in GPCRs. The present study focused on the opsin mutant E134Q/M257Y, which showed a moderate level of constitutive activity and the formation of two distinct rhodopsin chromophores with absorption maxima of 500 nm and 380 nm, depending on the presence of an inverse agonist, 11-cis-retinal, and an agonist, all-trans-retinal, respectively. Reconstitution of the mutant rhodopsin upon incubation with different ratios of 11-cis-retinal and the all-trans-retinal, as well as upon sequential binding of the two retinals, indicated its preferential binding to 11-cis-retinal. The thermal stability of the 11-cis-retinal-bound form of the E134Q/M257Y mutant was lower than that of the mutants containing a single replacement but higher than that of the all-trans-retinal-bound forms. The mutant also showed a lower stability in its opsin state as compared with that of the wild-type opsin but had little effects on the binding affinity to 11-cis-retinal. Information obtained in this study will be helpful for analyzing the structural changes associated with the activation of rhodopsin and GPCRs.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.4
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• pp.162-174
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• 2012

To visualize the characteristics of vertical seawater temperature data, in the ocean having 3D spatial characteristics, 2D thematic maps like horizontal seawater temperature distribution map at each depth layer and 3D volume model using 3D spatial interpolation are used. Although these methods are useful to understand oceanographic phenomena visually, there is a limit to analyze the spatial pattern of vertical temperature distribution or the relationship between vertical temperature characteristics and other oceanic factors (seawater chemistry, marine organism, climate change, etc). Therefore, this study aims to determine the spatial distribution characteristics of vertical temperature profiles in the South Sea of Jeju by quantifying the characteristics of vertical temperature profiles by using an algorithm that can extract the thermocline parameters, such as mixed layer depth, maximum temperature gradient and thermocline thickness. For this purpose spatial autocorrelation index (Moran's I) was calculated including mapping of spatial distribution for three parameters representing the vertical temperature profiles. Also, after grouping study area as four regions by using cluster analysis with three parameters, the characteristics of vertical temperature profiles were defined for each region.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.477-482
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• 2015

This study examined the adsorption characteristics of heavy metal ions ($Cr^{6+}$, $As^{3+}$) in an aqueous solution using recycled aggregate (RA) and recycled aggregate (RA)/steel slag (SS) composites. The RA and SS are favorable for the absorbent because it contains about 91% and 86.9%, respectively, which are some of the major adsorbent ingredients (CaO, $SiO_2$, $Al_2O_3$ and $Fe_2O_3$) for heavy metal. Kinetic equilibrium of $Cr^{6+}$ and $As^{3+}$ in RA and RA/SS composites reached within 180 min and 360 min, respectively. The kinetic data presented that the slow course of adsorption follows the Pseudo first and second order models. The equilibrium data were well fitted by the Freundlich model and showed the affinity order of $As^{3+}$ > $Cr^{6+}$. The results of $As^{3+}$ also showed that the adsorption capacity slightly increased with increasing pH from 6 to 10. Meanwhile, the adsorption capacity of $Cr^{6+}$ was slightly decreased. From these results, it was concluded that the RA and RA/SS composites can be successfully used for removing the heavy metals ($Cr^{6+}$ and $As^{3+}$) from aqueous solutions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.363-368
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• 2017

The tsunami flood the coastal cities and damage the land structures. The study on wave pressure and force on land structures is one of the important factors in designing the stability of inland structures. In this study, two - dimensional wave flume tests on the horizontal wave force and pressure of tsunamis on a simplified box-type structure was conducted. Vertical distribution and wave power of horizontal wave pressure over time were measured by pressure sensors and force transducer. Also, those were measured from the different wave breaking types. The vertical distribution of horizontal wave pressure was uniform at the moment when the horizontal wave force to the structure was maximum under the breaking wave condition. A surf similarity parameter was employed in order to figure out the relationship between the maximum horizontal wave force on the structure as a function of various incident wave conditions. As a result, the non - dimensionalized horizontal wave force tends to decrease exponentially as the surf similarity parameter increases.