• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.446-455
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• 2022

This study investigated work experience of firefighters and risk factors for their depression during COVID-19 pandemic. We analyzed data of 53,557 firefighters who participated in the online mental health status survey. Data included experiences of COVID-19 infection, experience of COVID-19 response work, fear of social stigma, and anxiety and depression symptoms. Results showed that 45.76% of participants had experience of COVID-19 response work. Emergency job group had the highest percentage of COVID-19 related work and the greater intensity of the work and fear of social stigma than those of other job groups. Hierarchical multiple regression showed that co-workers' infection, COVID-19 related work intensity and fear of social stigma were significantly associated to the severity of depression. The findings in this study demonstrated COVID-19 related work experience can link to the development of depression in firefighters. Effort to reduce COVID-19 related work intensity and fear of social stigma could help prevent depression among firefighters.

• Transactions on Electrical and Electronic Materials
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• v.13 no.5
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• pp.256-261
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• 2012

Recently, many photovoltaic systems (PV systems) including solar parks and PV farms have been built to prepare for the post fossil fuel era. To investigate the degradation process of the PV systems and thus, efficiently operate PV systems, there is a need to visually monitor PV systems in the range of infrared ray through the Internet. For efficient visual monitoring, this paper explores a multithreaded implementation of a recently developed HEVC standard whose compression efficiency is almost two times higher than H.264. For an efficient parallel implementation under a meshbased 64 multicore system, this work takes into account various design choices which can solve potential problems of a two-dimensional interconnects-based 64 multicore system. These problems may have not occurred in a small-scale multicore system based on a simple bus network. Through extensive evaluation, this paper shows that, for an efficient multithreaded implementation of HEVC intra prediction in a mesh-based multicore system, much effort needs to be made to optimize communications among processing cores. Thus, this work provides three design choices regarding communications, i.e., main thread core location, cache home policy, and maximum coding unit size. These design choices are shown to improve the overall parallel performance of the HEVC intra prediction algorithm by up to 42%, achieving a 7 times higher speed-up.

• Korean Journal of Computational Design and Engineering
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• v.20 no.3
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• pp.291-297
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• 2015

A water jet cleaning robot system for micro drill bits is to refurbish micro drill bits used for the PCB manufacturing process. It can refurbish drill bits with the minimum diameter of ${\phi}0.15{\sim}0.075mm$ of which the total quantity have been discarded before. Micro drill bits with the minimum diameter of ${\phi}0.075mm$ can be cleaned by applying the water jet cleaning robot system out of the manual ultrasonic cleaning in the past for the cleaning equipment as the initial process in refurbishing. This study analyzed problems, while applying the apparatus mechanism for the workability such as the robot traces of Transfer Robot I and II, drill bit loading and unloading, and cleaning tasks in the water jet cleaning robot system in an effort to carry out simulations. In addition, the cleaning work process was optimized as the work process was verified in advance and the production quantity was analyzed through simulations.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.71-76
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• 2009

The research to predict the resistance performance of the ship using the CFD analysis is increasing. For the CFD numerical analysis the computational mesh, which is proper to computational model, has to be made before the analysis is begun. In the parametric study, even though the deformation of each case is not very sharp, the whole computational mesh should be regenerated according to the conventional way. Hence, lots of effort is needed to repeated mesh generation work. To solve these problems, the automatic mesh generation method using the macro function of commercial CAD program and mesh generation program is introduced in this study. First, in the CAD program, by using the macro function and putting the deformation rate of bow and stern in lengthwise, the repeated modeling work is performed automatically. Next, the generated geometries are read by the mesh generation program and the proper mesh for the geometry is created automatically also using the macro function. The hybrid mesh which has unstructured grid near the bow and stern and structured grid in the remaining part of domain is used. The verification of the developed method is done by applying the method to predict the resistance performance of the podded propulsion cruise ship of the Daewoo Shipbuilding & Marine Engineering (DSME) in the cases of different length of bow and stern and pod set in different position. The author believes that the introduced method can help to make the database to optimize the resistance performance of the ship in various cases can be constructed without difficulty.

• Journal of Hydrogen and New Energy
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• v.21 no.6
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• pp.570-579
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• 2010

Since the temperature of waste heat source is relatively low, it is difficult to maintain high level of efficiency in power generation when the waste heat recovery is employed in the system. In an effort to improve the thermal efficiency and power output, use of ammonia-water mixture as a working fluid in the power cycle becomes a viable option. In this work, the performance of ammonia-water mixture based Rankine cycle is thoroughly investigated in order to maximize the power generation from the low temperature waste heat. In analyzing the power cycle, several key system parameters such as mass fraction of ammonia in the mixture and turbine inlet pressure are studied to examine their effects on the system performance. The results of the cycle analysis find a substantial increase both in power output and thermal efficiency if the fraction of ammonia increases in the working fluid.

• Journal of Gifted/Talented Education
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• v.3_4 no.1
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• pp.139-147
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• 1994

The "First Step to Nobel Prize in Physics" is an annual competition in research projects in physics for secondary (high) school pupils organized by the Institute od Physics, Polish Academy of Sciences. This year the second competition of that type has been completed. Pupils from 36 countries took part in the first two competitions, what certainly should be treated as a great success. We have organized the above competition for the following reasons. During our contacts with secondary school pupils we discovered that some of them try to perform different physical investigations by themselves: at schools, in some laboratories and even at home. Then we decided to organize the National Competition in Pupils' Research Projects in Physics and next - after gaining some experience in the national scale - the international competition "First Step to Nobel Prize in Physics". Our aim was to recognize the effort of the pupils, give them a chance to compare their own achievements with the achievements of their colleagues and organize their work. One should underline that the "First Step" refers to quite different features (long term research work) of the pupils than the International Physics Olympiad (solving well formulated physics problems). The prizes in our competition are not typical. Instead of buying some items for our winners we decided to invite them to our Institute for a research stay. In our opinion in case of people whose hobby is physics such a form of prize is more valuable and more instructive than anything else. The aim of this article is to discuss a genesis of the competition, to present conditions of participation and to discuss the results.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.517-522
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• 2010

The riffle and pool play an important role for composing river front, but very little information was used for river restoration considering flood control. In this paper extensive field investigation was carried out to estimate hydraulic processes in the pool. Furthermore diurnal stratification model was developed and applied to assess flow change in pool. The physical mechanism of water flow including diurnal processes was well simulated, the results show that diurnal variation of water flow in the pool about 2 m depth is governed by the level of mixing due to density flow. These effort will be useful to guide field data collection work and to understand primary production.

• Progress in Superconductivity
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• v.6 no.1
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• pp.7-12
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• 2004

Due to the very fast switching speed of Josephson junctions, superconductive digital circuit has been a very good candidate fur future electronic devices. High-speed and Low-power microprocessor can be developed with Josephson junctions. As a part of an effort to develop superconductive microprocessor, we have designed an RSFQ 4-bit ALU (Arithmetic Logic Unit) in a pipelined structure. To make the circuit work faster, we used a forward clocking scheme. This required a careful design of timing between clock and data pulses in ALU. The RSFQ 1-bit block of ALU used in this work consisted of three DC current driven SFQ switches and a half-adder. We successfully tested the half adder cell at clock frequency up to 20 GHz. The switches were commutating output ports of the half adder to produce AND, OR, XOR, or ADD functions. For a high-speed test, we attached switches at the input ports to control the high-speed input data by low-frequency pattern generators. The output in this measurement was an eye-diagram. Using this setup, 1-bit block of ALU was successfully tested up to 40 GHz. An RSFQ 4-bit ALU was fabricated and tested. The circuit worked at 5 GHz. The circuit size of the 4-bit ALU was 3 mm ${\times}$ 1.5 mm, fitting in a 5 mm ${\times}$ 5 mm chip.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.491-498
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• 2004

In recent years, as an effort to grasp the leading position in the field of maritime trading, new ports and container terminals arc now under construction. Old ports are extended. At the beginning, stones were thrown down to form stone embankments, that is stone-dams, in the outer and inner boundaries of the planned reclamation-land. S.C.P(Sand Compaction Pile) works are often needed to improve the stability of stone-dams, where marine sediments arc relatively thick. Here, interests are centered on the shape of stone body. In this, drilling work won't provide a sufficient resolution. In addition, the result corresponds to only one borehole point information. Thus, the aim of this paper is to introduce an affordable technology, that is, a combined geophysical method(seismic tomography + Televiewer) enables to get the whole information about stone-dam section. The measuring and evaluating procedure is described in detail with an emphasis on dealing with the use of seismic detonator, proper borehole deployment and integrated data analysis. Examples of field experiments at Busan new port are illustrated, which will prove the benefit of combined geophysical method.

• Korean Journal of Community Nutrition
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• v.3 no.1
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• pp.120-132
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• 1998

A major goal of the Community Plant Food Project is to develop partnerships between the Cornell Community Nutrition Program and Community-based organizations, including Cooperative Extension. A core principle behind this work is integrating research and intervention. Based on our work in Rochester, New York, we have developed a process and principles for effective partnerships. This new paradigm what we call the University-Community Partnership Model is a team effort that builds on the experiential literature in the fields of communication, leadership, community and team development, sociology, and participatory research and action. We have applied this model both to increase our understanding of Family Food Decision-making and to develop programs for families. In this project, we have used a variety of qualitative methods to understand food decisions from the perspectives of families and community stakeholders, including a group method for analyzing our qualitative interview data. For our survey of families, we developed the Enhanced Response Method, an approach for improving the validity and reliability of community surveys with families and, at the same time, building relationships with families and other stakeholders in the community for integrated and sustainable interventions. Because the knowledge we develop through the partnership and the interventions we seek to implement are products of the process, we are constantly seeking to refine this knowledge and to adapt emerging interventions through an ongoing evaluation process we call the Continuous Improvement Method.