• Korea journal of population studies
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• v.6 no.1
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• pp.3-42
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• 1983

The purposes of this paper is to introduce a technique for construction of nuptiality tables using proportion single of synthetic cohorts between times at two consecutive censuses, and to observe patterns of change in marriage habit of Korean through the nuptiality tables for single population from 1925 to 1980. In this paper abridged gross and net nuptiality tables for single population of Korea have been constructed for the four quinquinial period: 1925-1930, 1955-1960, 1970-1975, and 1975-1980. Significant time trend has been observed in the nuptiality rates among the single population. The major findings observed in each table are as follows; (1)During 1925-1930, the rates are initially small, but increase rapidly until they reach a maximum at ages 25-29 for bachelors and 20-24 for spinsters, following which they are still in high level. (2)During 1955-1960, the age pattern of nuptiality begins to change; for female population, the rates increase rapidly in the same pattern as in l925-l930 untill they reach the highest level at ages 25-29, after which they gradually decline. During the period, however, there were an unprecedented high level of marriage rates for male population at a relatively later ages. (3)During 1970-1975, Korea had experienced a transition in marriage habits; at this times, nuptiality rates for both sexes showed the same pyramid shaped patterns as in western countries as age increases. The mean ages at marriage for both sexes also reached the highest level of 27.5 years for males and 24.1 years for females. (4)During 1975-1980, the age patterns of nuptiality showed almost the same patterns as in 1970-1975. In the later age group, however, age-specific marriage rates for both sexes greatly declined compared to the level of 1970-1975, while the rate in age group of 20-24 for male population greatly increased.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.4
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• pp.253-262
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• 2004

Construction of tunnels in a deep crystalline host rock for a potential High-Level Radioactive Waste(HLW) repository inevitably generates an excavation disturbed zone (EDZ). There have been a series of debates on whether a permeability in an EDZ increases or not and what would be the maximum depth of an EDZ. Recent studies show mixed opinions on permeability. However, there has been an international consensus on the thickness of an EDZ; 30 cm for TBM and 1 meter for controlled blast. One of the impacts of an EDZ is on determining the distance between adjacent deposition holes. The void gap by the excavation hinders relaxation of temperature profiles so that the current Korean reference designing distance between holes should be stretched out more to keep the maximum temperature in a buffer region below 100 degrees Celsius. The other impact of an EDZ is on the long-term post closure radiological safety. To estimate the impact, the reference scenario, the well scenario, is chosen. Released nuclides diffuse through a bentonite buffer region experiencing strong sorption and reach a fracture surrounded by a porous medium. Inside a fractured porous region, radionuclides migrate by advection and dispersion with matrix diffusion into a porous medium. Finally, they reach a well assumed to be a source of potable water for local residents. The annual individual dose is assessed on this well scenario to find out the significance of an EDZ. A profound sensitivity study was performed, but all results show that the impact is negligible. Even though the role of an EDZ turns out to be limited on overall safety assessment, still it is worthwhile to study the chemical role of an EDZ, such as a potential source for natural colloids, potential sealing of an open fracture by fine clay particles generated by the process of an EDZ, and alteration of a sorption mechanism by an EDZ in the future.

• Korea journal of population studies
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• v.5 no.1
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• pp.4-16
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• 1982

The Korean Population Control Program has been implementing under the jurisdiction of the Ministry of Health and Social Affairs through an existing network of health centers. This arrangement was successful in bringing population growth down to targeted level by the end of the Fourth Five Year Economic Planning, 1981. It is expected, however, that future goal will be harder to reach due to difficulty of reducing traditional family size norms further and to the projected increasing the number of eligible couples as the past Korean war baby boom generation enters the reproductive activity in the next few years. The recognition of the need for modification of population policy is increasing. The 1980 census shows that the total number of population reached approximately 38.5 million with 1.57 per cent of the growth rate. It was projected that the size of Korean Population will reach around 42 million and 51 million in 1986 and 2000 respectively. Furthermore, there is some argument as to whether decline in the birth rate in Korea is too slow to meet government target. Hence, a new development of population policy and greatly increased amount of effort will be needed in order to achieve Zero Population Growth Rate before the year 2050. The development of future national population policy and its related area are recommended as follow: 1. It is highly recommended that the population planning law governing both vital events of birth and death and population migration should be legislated. 2. The National Population Policy Council, Chaired by Deputy Prime Minister should be activated to implement and coordinate population program within ministries. 3. Responsible organization of population and family planning program should be established as a Bureau unit at central government level. 4. For the improvement of national vital registration, an existing system should be studied and developed.

• Journal of Climate Change Research
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• v.9 no.4
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• pp.471-485
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• 2018

The Republic of Korea (ROK) has made many efforts to reduce greenhouse gases through a legal framework, making obligations to reach domestic and overseas targets via the Paris Convention in 2015. China recently launched a nation-wide emission trading system (ETS) and has considered extending this ETS to include the ROK. This study examines the possibility of linking the ETS between ROK and China by considering the institutional design elements of the ETS. Additionally, this study provides policy implications to reach Korea's overseas reduction target. For the research methodology, the design elements of both the ROK and China policies were analyzed by categorizing their standard design elements based on the International Carbon Action Partnership. This paper focuses on four main barriers (cap type, borrowing, offset and price ceiling) based on their environmental benefits and analyzes the challenges to combining the design elements between the ROK and China systems. The two ETS commonly share the same cap types, and there is similar institutional progress regarding the offset and price ceiling. In addition to this, note that China has a borrowing system that is opposite to the borrowing system in ROK. According to these findings, there are major challenges to linking the ROK and China systems due to differences in the major design elements. Thus, it is necessary to modify the Korean domestic borrowing system and understand the Chinese institutional processes related to environmental negotiation to achieve further cooperation.

• Journal of the Korea Society for Simulation
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• v.27 no.4
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• pp.1-8
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• 2018

The most common way to control a target point using artificial intelligence is through reinforcement learning. However, it had to process complicated calculations that were difficult to implement in order to process reinforcement learning. In this paper, the enhanced Proximal Policy Optimization (PPO) algorithm was used to simulate finding the planned flight trajectory to reach the target point in the virtual environment. In this paper, we simulated how this problem was used to find the planned flight trajectory to reach the target point in the virtual environment using the enhanced Proximal Policy Optimization(PPO) algorithm. In addition, variables such as changes in trajectory, effects of rewards, and external winds are added to determine the zero conditions of external environmental factors on flight trajectory learning, and the effects on trajectory learning performance and learning speed are compared. From this result, the simulation results have shown that the agent can find the optimal trajectory in spite of changes in the various external environments, which will be applicable to the actual vehicle.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.3
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• pp.1-9
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• 2019

Purpose : To find out how action observation training for chronic stroke patients affects their balance and body control abilities in the posture seated in the rehabilitation of stroke. Methods : This study was conducted on 30 subjects who were diagnosed with stroke. The group conducted motion observation training through video clips, while the control group only conducted physical training, and the general physical therapy was performed equally by both counties. The static balance was measured using Biorescue and the dynamic balance was measured using Modified Functional Reach Test (MFRT), Postural Assessment Scale for Stroke, and Trunk Impairment Scale. Results : Static balance showed statistically significant difference in foot pressure (p<.05) as a result of comparison between pre and post exercise training. Dynamic balance was statistically significant (p>.05) as a result of comparing pre and post differences using modified functional reach test. The trunk control ability was statistically significant (p>.001). Comparison between the results of before and after motion observation training showed a statistically significant difference. Conclusion: This study confirmed that exercise training in sitting position was effective for static, dynamic balance ability and trunk control ability of hemiplegic patients due to stroke. These results suggest that the use of motion monitoring in stroke patients may have a positive impact on the diversity and function of rehabilitation.

• Journal of Korea Water Resources Association
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• v.54 no.1
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• pp.15-25
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• 2021

The purpose of this study was to present the necessity and effect of culvert fishway, based on the absence of design criteria for it which fishes can pass. As an attempt for this purpose, circular culvert fishway were designed hydraulically to meet the passage condition for selected target fish species, and post-monitoring was performed to confirm its effectiveness. In the case of general circular culvert without weir baffles, the target fish species cannot pass because of the constant depth and velocity in the entire reach of the circular culvert, so it was confirmed that resting pools must be installed to help fish passage. In the case of circular culvert with weir baffles, the depth and the mean velocity in resting pool increased by about 240% and decreased by about 70% respectively, which not only satisfied the passage conditions of Zacco platypus that can swim at more than 10 times the speed of body length for 1 to 5 seconds, but also confirmed that various river fish could pass. Post-monitoring results of the restoration reach and fish capture monitoring surveys of circular culvert fishway demonstrated that the target fish species, Zacco platypus, can pass through it.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.19-27
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• 2017

This paper is a study to improve the fire-resistance capacity of reinforced concrete (RC) members strengthened by fiber-reinforced-polymer (FRP). The fire resistance of the RC members strengthened by FRP was evaluated through high temperature exposure test. In order to improve the fire resistance of the FRP reinforcing method, a fire-proof board was attached to the reinforced FRP surface and then the high temperature exposure test was carried out to evaluate the improvement of the fire resistance performance. It was confirmed that the resistance to high temperature of NSMR could be improved somewhat compared with that of EBR from the experiment that exposed to high temperature under the load corresponding to 40% of nominal strength. When 30 mm thick fire-resistance (FR) board is attached to the FRP surface, the surface of the reinforced FRP does not reach $65^{\circ}C$, which is the glass transition temperature (GTT) of the epoxy until the external temperature reaches $480^{\circ}C$. In particular, when a high performance fire-proof mortar was first applied prior to FR board attachment, the FRP portion did not reach the epoxy glass transition temperature until the external temperature reached $600^{\circ}C$.

• Journal of the Korean Society of Safety
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• v.38 no.3
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• pp.35-42
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• 2023

This study analyzed the current and temperature characteristics of major components of an induction motor during normal and abnormal operations as functions of the difference in the rated capacities of medium and large-sized motors widely used in industrial settings. The temperature rise equation of the induction motor winding was derived through locked-rotor operation experiments and linear regression analysis. When the ambient temperature is 40 ℃, the time to reach 155 ℃, the temperature limit of the insulation class (F class) of the winding of the induction motor, was confirmed to be 48 seconds for the 2.2 kW induction motor and 39 seconds for the 3.7 kW induction motor. This means that when the rated capacity is large or the installation environment is high temperature, the time to reach the temperature limit of the insulation class during locked-rotor operation is short, and the risk of insulation deterioration and fire is high. In addition, even if the EOCR (Electronic Over Current Relay) is installed, if the setting time is excessively set, the EOCR does not operate even if the normal and locked-rotor operation of the induction motor is repeated, and the temperature limit of the insulation grade of the winding of the induction motor is exceeded. The results of this study can be used for preventive measures such as the promotion of electrical and mechanical measures for the failure of induction motors and fire prevention in industrial sites, or the installation of fire alarm systems.

• Advanced Industrial SCIence
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• v.2 no.2
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• pp.16-24
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• 2023

Purpose: This study was conducted to find out the immediate effect on dynamic balance through Abdominal hollowing exercise and Abdominal bracing exercise. Method: 90 healthy male and female students in their 20s were surveyed and measured using Y-balance test and Functional reach test. Result: In the dynamic balance Test between groups, there was a statistically significant difference between the group that performed Abdominal hollowing exercise and the control group. Conclusion: Although both representative spinal stabilization exercises Abdominal hollowing exercise and Abdominal bracing exercise are meaningful in increasing dynamic equilibrium, it is difficult to suggest that any method is more effective in terms of immediate effects.