• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.177-186
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• 2017

This study is intended to provide navigator with specific information necessary to assist in the avoidance of collision and in operation of ships to evaluate the maneuverability of research vessel Jera. Authors carried out full-scale sea trials for turning test, zig-zag test, and spiral test at actual sea-going condition, which were performed on starboard and port sides with 10-20 rudder angle at service speed of 10 knots. The turning circle was much different at both of the turning of port and starboard which was longer at the starboard than at the port. In the zig-zag test results, the port and starboard was $10^{\circ}$ the first and second overshoot angles were $6.0^{\circ}$, $5.8^{\circ}$ and $6.3^{\circ}$, $7.1^{\circ}$ respectively and the first overshoot angles were $16.4^{\circ}$, $17.6^{\circ}$ when using $20^{\circ}$. Her maneuverability index T and N can be easily determined by using an analogue computer with the data obtained from the zig-zag tests where K is a constant representing the turning ability and T is a constant representing her quick response. In the zig-zag tests under $10^{\circ}$ or $20^{\circ}$ at rudder angle, the value K is 0.149. 0.123 sec- and T is 11.853 and 6.193 sec and angular velocity is $0.937^{\circ}/sec$ and $1.636^{\circ}/sec$. In the spiral test, the loop width was unstable at $+0.51^{\circ}$ and $-1.19^{\circ}$ around the midship of rudder, but the tangent line at $0^{\circ}$ was close to vertical. From the sea trial results, we found that she did comply with the present criterion in the standards of maneuverability of IMO.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.9-15
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• 2006

At the adjacent sea area of Busan Central Wharf, a variety of vessels, such as middle-large passenger ships, small hugh speed crafts, container ships, cargo ships and working boats as well as small miscellaneous vessels are freely sailing comparatively without special rules and marine traffic control. In this research, we analyzed traffic stream and navigational characteristics cf main traffic route based on statistics and distribution of tracks by ship's type and tonnage cf the passing vessels after conducting marine traffic survey twice using exclusive software. We examined the traffic safety of the passing vessels by classifying the sea area by each function based on the analysis about this traffic situation, and analyzing the effect by designating 'Inner passage'. We also studied the plan for the effective rearrangement cf Central Wharf considering basically the traffic safety of arrival and departure in a point of view of navigators.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.647-654
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• 2016

Indoor localization based on visible-light communication using the received signal strength intensity (RSSI) has been widely studied because of its high accuracy compared with other wireless localization methods. However, because the RSSI can vary according to the inclination and azimuth of the receiver, a large error can occur, even at the same position. In this paper, we propose a visible-light communication-based 3-D indoor positioning algorithm using the Gauss-Newton technique in order to reduce the errors caused by the change in the inclination of the receiver. The proposed system reduces the amount of computations by selecting the initial position of the receiver through the linear least-squares method (LSM), which is applied to the RSSIs, and improves the position accuracy by applying the Gauss-Newton technique to the 3-D nonlinear model that contains the RSSIs acquired by the changes in the azimuth and inclination of the receiver. In order to verify the validity of the proposed algorithm in an indoor space with dimensions of $6{\times}6{\times}3m$ where 16 LED lights are installed, we compare and analyze the errors of the conventional linear LSM-based trilateration technique and the proposed algorithm according to the changes in the inclination and azimuth of the receiver. The experimental results show that the location accuracy of the proposed algorithm is improved by 82.5% compared to the conventional LSM-based trilateration technique.

• Journal of Convergence for Information Technology
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• v.8 no.4
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• pp.237-245
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• 2018

The purpose of this study is to suggest the improvement plan for an effective benefit sharing support policy through empirical analysis on the benefit sharing operation of government as well as the benefit sharing support policy of government affecting firm performance. Therefore, this study analyzed current problems on benefit sharing operation of government as well as performed a survey for 225 participating and cooperation firms regarding firm performance. This study found some improvements such as insufficient diverse incentive measures leading to the difficulty of participating firm's increase and spread, insufficient substantial benefit sharing such a cash allocation between consignment firms, the increase of biz management system model failing to induce innovation of new technology or product, and difficult spread into 2nd, 3rd cooperative firms besides 1st ones, meanwhile, verifying the positive influence of government benefit sharing support policy on both participating and cooperation firms, especially on the performance of cooperation firms. As a further study, it is necessary to increase the objectiveness and accuracy of a research through verification of the interrelationships between firm statue and performance on the basis of more objective and quantitative data such a sales increase or R&D capability of cooperation firms.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.1
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• pp.74-85
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• 2013

Since the underground transportation system is a closed environment, indoor air quality problems may seriously affect many passengers' health. The purpose of this study was to understand $PM_{10}$ characteristics in the underground air environment and further to quantitatively estimate $PM_{10}$ source contributions in a Seoul Metropolitan subway station. The $PM_{10}$ was intensively collected on various filters with $PM_{10}$ aerosol samplers to obtain sufficient samples for its chemical analysis. Sampling was carried out in the M station on the Line-4 from April 21 to 28, July 13 to 21, and October 11 to 19 in the year of 2010 and January 11 to 17 in the year of 2011. The aerosol filter samples were then analyzed for metals, water soluble ions, and carbon components. The 29 chemical species (OC1, OC2, OC3, OC4, CC, PC, EC, Ag, Al, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Si, Ti, V, Zn, $Cl^-$, $NO_3{^-}$, $SO_4{^{2-}}$, $Na^+$, $NH_4{^+}$, $K^+$, $Mg^{2+}$, $Ca^{2+}$) were analyzed by using ICP-AES, IC, and TOR after proper pretreatments of each sample filter. Based on the chemical information, positive matrix factorization (PMF) model was applied to identify the $PM_{10}$ sources and then six sources such as biomass burning, outdoor, vehicle, soil and road dust, secondary aerosol, ferrous, and brakewear related source were classified. The contributions rate of their sources in tunnel are 4.0%, 5.8%, 1.6%, 17.9%, 13.8% and 56.9% in order.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.5
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• pp.554-563
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• 2006

Numerous epidemiological studies have shown stronger associations between $PM_{2.5}$ and both mortality and morbidity than $PM_{10}$. The association of $PM_{2.5}$ with respiratory mortality was examined in Seoul, during the period of $1996{\sim}2002$. Because $PM_{2.5}$ data were available for only 10% of this time period, a prediction regression model was developed to estimate $PM_{2.5}$ concentration. Death count due to respiratory-related diseases(total respiratory mortality; ICD-10, J00-J98) and death counts(cause-specific mortality) due to pneumonia(ICD-10, J12-J18), COPD(ICD-10, J40-J44) and asthma(ICD-10, J45-J46) were considered in this study. Averaged daily mortality was 5.6 for total respiratory mortality and 1.1 to 1.6 for cause-specific mortality. Generalized additive Poisson models controlling for confounders were used to evaluate the acute effects of particle exposures on total respiratory mortality and cause-specific mortality. An IQR increase in 5-day moving average of $PM_{2.5}(22.6{\mu}g/m^3)$ was associated with an 8.2%(95% CI: 4.5 to 12.1%) increase in total respiratory mortality The association of $PM_{2.5}$ was stronger for the elderly ($\geq$65 years old, 10.1%, 95% CI: 5.8 to 14.5%) and for males(8.9%, 95% CI: 2.1 to 11.3%). A $10{\mu}g/m^3$ increase in 5-day moving average of $PM_{2.5}$ was strongly associated with total respiratory mortality in winter(9.5%, 95% CI: 6.6 to 12.4%), followed by spring(3.1%, 95% CI: -1.2 to 7.5%), which was a different pattern with the finding in North American cities. However, our results are generally consistent with those observed in recent epidemiological studies, and suggest that $PM_{2.5}$ has a stronger effect on respiratory mortality in Seoul.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.403-408
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• 2005

The techniques of estimating angle of arrival(AOA) have played a key role for enhancement of wireless communications using array antennas. Among those techniques, the superresolution algorithms, such as MUSIC and ESPRIT, calculate the covariance matrix of the array output vectors which are observed at the array antennas, and then by using eigen-decomposition of the covariance matrix, they estimate AOAs of the received signals with high accuracy. However, superresolution algorithms based eigenvalue decomposition fails to estimate AOAs under multipath environments. Under multipath environments, it is difficult to estimate AOAs of the received signals due to coherency and high-correlation. To resolve coherent signals, the covariance matrix is calculated by using the conventional spatial smoothing technique, and then the techniques based on eigen-descomposition is applied. The result of the conventional spatial smoothing technique, however, is obtained at the cost of losing effective spatial aperture. Moreover, the conventional technique ignores any information in the cross-correlations of the array outputs the subarrays. As the result, the performance for AOA estimation is degraded. In this paper, we propose a new spatial smoothing technique, which consider the cross-correlation for subarrays. By computer simulation, the AOA estimation performance of the proposed method is compared with the conventional method and evaluated.

• The Korean Society of Law and Medicine
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• v.23 no.2
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• pp.67-96
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• 2022

"Aid in Dying" means that when a decision-making patient suffers from an incurable disease, a drug that can speed up death is prescribed by a doctor and used to lead to death. Since the suspension of life-sustaining treatment was institutionalized based on human dignity and patient autonomy, the question of whether assisted death can be legally justified in relation to the right to receive medical help to shorten one's life to die with dignity has recently been actively discussed. In Korea, since the suspension of life-sustaining treatment was institutionalized by the enactment of the Life-sustaining Treatment Decision Act in 2016, an amendment to the Life-sustaining Treatment Act was recently proposed to legalize Aid in Dying. The global trend is that human "Right to Die" is discussed in the division of life and death, from the suspension of life-sustaining treatment to assisted death, and again in the order of euthanasia. In this paper, we started discussing dignified death and institutionalized patients' right to self-determination, looked at the controversy in the United States, which legislated assisted death in many states since the 2000s, and analyzed the main contents of California's End of Life Option Act and the data after enforcement. The strict requirements for Aid in Dying, such as voluntary confirmation of patients' intentions and doctors' obligation to provide information, and the results of California's Aid in dying system, composed of relatively diverse races, were reviewed.

• Journal of Navigation and Port Research
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• v.47 no.1
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• pp.1-9
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• 2023

Many studies have analyzed marine accidents, and since marine accident information is updated every year, it is necessary to periodically analyze and identify the causes. The purpose of this study was to prevent accidents by identifying and analyzing the causes of marine accidents using previous and new data. In marine accident data, 1,921 decisions by the Korea Maritime Safety Tribunal on marine accidents on fishing ships over 16 years were collected in consideration of the specificity of fishing ships, and 1,917 cases of accident notification text history by the Ministry of Maritime Affairs and Fisheries over 3 years were collected. The decision data and text data were classified according to variables and quantified. Prior probability was calculated using a Bayesian network using the quantified data, and fishing ship marine accidents were predicted using backward propagation. Among the two collected datasets, the decision data did not provide the types of fishing ships and fishing areas, and because not all fishing ship accidents were included in the decision data, the text data were selected. The probability of a fishing ship marine accident in which engine damage would occur in the West Sea was 0.0000031%, as calculated by backward propagation. The expected effect of this study is that it is possible to analyze marine accidents suitable for the characteristics of actual fishing ships using new accident notification text data to analyze fishing ship marine accidents. In the future, we plan to conduct research on the causal relationship between variables that affect fishing ship marine accidents.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.1
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• pp.55-67
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• 2021

Hornbeams (Carpinus spp.), which are widely distributed in South Korea, are recognized as one of the most abundant species at climax stage in the temperate forests. Although the distribution and vegetation structure of the C. laxiflora community have been reported, little ecological information of C. tschonoskii is available. Little effort was made to examine the distribution shift of these species under the future climate conditions. This study was conducted to predict potential shifts in the distribution of C. laxiflora and C. tschonoskii in 2050s and 2090s under the two sets of climate change scenarios, RCP4.5 and RCP8.5. The MaxEnt model was used to predict the spatial distribution of two species using the occurrence data derived from the 6th National Forest Inventory data as well as climate and topography data. It was found that the main factors for the distribution of C. laxiflora were elevation, temperature seasonality, and mean annual precipitation. The distribution of C. tschonoskii, was influenced by temperature seasonality, mean annual precipitation, and mean diurnal rang. It was projected that the total habitat area of the C. laxiflora could increase by 1.05% and 1.11% under RCP 4.5 and RCP 8.5 scenarios, respectively. It was also predicted that the distributional area of C. tschonoskii could expand under the future climate conditions. These results highlighted that the climate change would have considerable impact on the spatial distribution of C. laxiflora and C. tschonoskii. These also suggested that ecological information derived from climate change impact assessment study can be used to develop proper forest management practices in response to climate change.