• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.10
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• pp.941-946
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• 2010

This study aims to investigate the effects of soybean biodiesel fuel on exhaust emissions with regards to two combustion modes: conventional combustion(existence of PM-NOx trade-off behavior) and low temperature combustion(LTC) in a 1.7 L common rail direct injection diesel engine. As compared to conventional combustion, LTC was achieved by adopting a heavier exhaust gas recirculation and strategic injection parameter optimization. Two sets of fuels, i.e. ultra low sulfur diesel(ULSD) and 20% volumetric blends of soybean biodiesel with ULSD(B20) were used. Regardless of the fuel type, in LTC the simultaneous reduction of PM and NOx was observed and both levels were significantly lower than in case of conventional combustion. Under the given engine operating condition in the case of conventional combustion, B20 produced less PM and more NOx than ULSD. In the case of LTC combustion, B20 produced more PM and NOx than ULSD.

• Health Policy and Management
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• v.28 no.3
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• pp.257-262
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• 2018

This study reviews the advent of long-term care (LTC) hospitals and its key issues in Korea. For analysis, enforcement ordinances and enforcement rules related to LTC hospitals were reviewed. Official statistic data were used for quantitative analysis and Organization for Economic Cooperation and Development data were utilized for comparative analysis. Various references and expert interviews were conducted for status analysis. As of 2016, the number of LTC hospitals was 1,386 and the number of beds were 246,373. It showed the trend of increasing medical care costs and the cost of care at LTC hospitals increasing from 998.8 billion Korean won in 2008 to 4,745.6 billion Korean won in 2016, accounting for 7.3% of the total National Health Insurance expenditure. From the societal perspective, several issues were pointed out within the current health care system related to LTC hospitals: establishment of roles, concerns about the increase in medical expenses, and the quality of medical personnel.

• Nuclear Engineering and Technology
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• v.33 no.1
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• pp.12-24
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• 2001

The post-LOCA long term cooling (LTC) performance of the Korean Standard Nuclear Power Plant (KSNPP) is analyzed for both small break loss-of-coolant accidents (LOCA) and large break LOCA at cold leg. The RELAP5/MOD3.2.2 beta code is used to calculate the LTC sequences based on the LTC plan of the Korean Standard Nuclear Power Plants (KSNPP). A standard input model is developed such that LOCA and the followed LTC sequence can be calculated in a single run for both small break LOCA and large break LOCA. A spectrum of small break LOCA ranging from \ulcorner.02 to 0.5 k2 of break area and a double-ended guillotine break are analyzed. Through the code calculations, the thermal-hydraulic behavior and the boron behavior are evaluated and the effect of the important action including the safety injection tank (SIT isolation and the simultaneous injection in LTC procedure is investigated. As a result, it is found that the sufficient margin is available in avoiding the boron precipitation in the core. It is also found that a further specific condition for the SIT isolation action need to be setup and it is recommended that the early initiation of the simultaneous injection be taken for larger break LTC sequences.

• Journal of Korean Public Health Nursing
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• v.36 no.2
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• pp.212-226
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• 2022

Purpose: The purpose of this study was to explore nurses' experience of the role adaptation process and barriers in long-term care (LTC) facilities including nursing homes, daycare centers, and home visit nursing centers. Methods: After in-depth interviews with 13 nurses who were working at the LTC facilities in G province, the data were analyzed using Colaizzi's phenomenological methodology. Results: 17 themes with 6 theme clusters, and 2 categories emerged: nursing role adaptation process in the LTC (role expectation and readiness, role perception and performance, limits of role performance), and barriers to nursing role adaptation in the LTC facility (organizational, situational, and institutional-environmental barriers). Conclusion: The results showed that it is critical to establish the nurses' role in caring for the health of the elderly and maintaining the quality of care in the LTC facilities. In response to the growing demand for quality care in the LTC facilities, more institutional and environmental changes are needed to address the current barriers that prevent nurses from performing their appropriate roles.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.150-152
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• 2022

In this work, we propose a model that considers the behavior and synaptic plasticity of sensory neurons based on Liquid Time-constant Network (LTC). The neuron connection structure was experimented with four types: the increasing number of neurons, the decreasing number, the decreasing number, and the decreasing number. In this study, we experimented using a time series prediction dataset to see if the performance of the changed model improved compared to LTC. Experimental results show that the application of modeling of sensory neurons does not always bring about performance improvements, but improves performance through proper selection of learning rules depending on the type of dataset. In addition, the connective structure of neurons showed improved performance when it was less than four layers.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.88-94
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• 2012

One of the effective ways to reduce both $NO_x$ and PM at the same time in a diesel CI engine is to operate the engine in low temperature combustion (LTC) regimes. In general, two strategies are used to realize the LTC operation-dilution controlled LTC and late injection LTC - and in this study, the former approach was used. In the dilution controlled regime, LTC is achieved by supplying a large amount of EGR to the cylinder. The significant EGR gas increases the heat capacity of in-cylinder charge mixture while decreasing oxygen concentration of the charge, activating low temperature oxidation reaction and lowering PM and $NO_x$ emissions. However, use of high EGR levels also deteriorates combustion efficiency and engine power output. Therefore, it is widely considered to use increased intake pressure as a way to resolve this issue. In this study, the effects of intake pressure variations on performance and emission characteristics of a single cylinder diesel engine operated in LTC regimes were examined. LTC operation was achieved in less than 8% $O_2$ concentration and thus a simultaneous reduction of both PM and $NO_x$ emission was confirmed. As intake pressure increased, combustion efficiency was improved so that THC and CO emissions were decreased. A shift of the peak Soot location was also observed to lower $O_2$ concentration while $NO_x$ levels were kept nearly zero. In addition, an elevation of intake pressure enhanced engine power output as well as indicated thermal efficiency in LTC regimes. All these results suggested that LTC operation range can be extended and emissions can be further reduced by adjusting intake pressure.

• Health Policy and Management
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• v.29 no.2
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• pp.195-205
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• 2019

Background: The food and food service influence the quality of life and the general health condition of older persons living in long-term care (LTC) facilities. Purchasing good food materials is a ground of good food service. In Korea, the residents in LTC facilities should pay for the cost of food materials and ingredients out of their pocket because it is not covered by LTC insurance. This study explored what factors affect the cost of food materials paid by LTC facility residents and which factor affects most. Methods: We used data from the study on out-of-pocket payment on national LTC insurance, which surveyed 1,552 family caregivers of older residents in LTC facilities. We applied conditional multi-level model, of which the first level represents the characteristics of care receivers and caregivers and its second level reflects those of LTC facilities. Results: We found that the facility residents with college-graduated family caregivers paid 11,545 Korean won more than those with less than elementary-graduated ones. However, the income level of family caregivers did not significantly affect the amount of the food material cost of the residents. The residents in privately owned, large, metropolitan-located facilities were likely to pay more than those in other types of facilities. The amount of the food material cost of the residents was mainly decided by the facility level factors rather than the characteristics of care recipients and their family caregivers (intra-class correlation=82%). Conclusion: These findings suggest that it might be effective to design a policy targeting facilities rather than residents in order to manage the cost of food materials of residents in LTC facilities. Setting a standard price for food materials in LTC facilities, like Japan, could be suggested as a feasible policy option. It needs to inform the choice of LTC users by providing comparable food material cost information. The staffing requirement of nutritionist also needs to be reviewed.

• Health Policy and Management
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• v.21 no.1
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• pp.115-131
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• 2011

Several common issues are encountered by countries - Germany, Japan, and the United States - that adopted long-term care (LTC) system. First, the demand for LTC and its associated costs have steeply risen following the implementation of the LTC policy. Second, ensuring the quality of services have been difficult. Third, the coordination of services among providers and between LTC and medical care has been inadequate. Learning from their experience, we suggest ways to improve the LTC system in Korea. The basic approach aims for efficiency over equity in the system. This would require promoting provider competition and consumer choice. We propose several policy options according to the major stakeholders. For consumers, cash benefits at fixed rates and personal savings accounts are feasible options to self-contain the demand and cost of services. On the insurer's side, creating an environment of multiple insurers will engender competition, leading to cost savings and quality care. For providers, delivery of quality services through competition, cost-containment through capitated reimbursements, and coordination of services through integrated delivery system can be achieved. From the assessors' perspective, establishing an information system to monitor the activities of insurers and providers would be important, empowering consumers with information to choose cost-effective service providers. In summary, the suggested approach would provide cost-effective LTC services by guaranteeing consumer choice and promoting major stakeholder accountability. Further studies are needed to test the feasibility of this model in ensuring quality LTC in Korea.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.31-38
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• 2009

Supercharging system was adopted to investigate the influence of boost pressure on operating range and exhaust emissions by using a supercharger at low temperature diesel combustion (LTC) condition in a 5-cylinder 2.7 L direct injection diesel engine. The experimental parameters such as injection quantity, injection timing, injection pressure and exhaust gas recirculation (EGR) rate were varied to find maximum operating range in LTC condition. As a result of adopting increased boost pressure in LTC, wider operating range was achieved compared with naturally aspirated condition due to increased mixing intensity. Increased boost pressure resulted in lower hydrocarbon (HC) and carbon monoxide (CO) emissions due to increased swirl rate and mixing intensity, which induced complete combustion. Moreover, increased boost pressure in LTC resulted in much lower soot emissions compared with high speed direct injection (HSDI) condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.120-127
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• 2014

Robustness and controllability are the key factors in internal combustion engine commercialization. This study focuses on the combustion strategy to commercialize the low temperature diesel combustion technology. Various LTC combustion methods such as PPCI, MK and highly diluted mixing controlled LTC were conducted on 6.0L heavy duty diesel engine. To find the best feasible LTC strategy, emission level, fuel consumption and combustion safety during the combustion mode change were considered. Experiments were carried out under various engine operating conditions; engine speed & load, EGR level, injection timing. Finally, this study suggests realizable LTC combustion strategy; moderate EGR level and slight early injection are possible to considerably lower PM, NOx emission and expand LTC operating range up to 50% load without CO and HC emission.