• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.13-19
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• 2010

Risk level for each construction work can be very important factors to establish advanced prevention measures. But it is important how to produce it. There are three different methods to set it up for construction situation. They are as follows; 1) occurrence frequency = the number of accident workers of each work kind / yearly accident workers 2) occurrence frequency = the number of accident workers of each work kind / yearly workers 3) occurrence frequency = the number of accident workers of each work kind / the total workers All these three concepts(=averaged concept)are analyzed. Additionally frequency based on discrete curve, and severity based on continuous curve are also combined for producing risk level with more scientific approach. This risk level can be very useful to make prevention plan or take measures at construction sites. This is study result can change existing risk level concept to new concept of it, namely rail way work and in-water work showed be high risk level and RC work be low risk level, different from the situation which we have thought commonly, so far.

• Journal of Korea Technology Innovation Society
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• v.8 no.1
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• pp.209-219
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• 2005

o Korea consumed total 198.5 million TOE and the portion of crude oil n was 100.4 million TOE in 2002 which marked the 10th largest energy consuming country and ranks the $4^{th}$ crude oil consumer in the world. o Industries consumed 51.5% of the total energy and 93% of industrial energy was used at the manufacturing industries such as steel, textile, chemical, food and beverage, pulp and paper, and timber industries, which lead to energy intensive industries numbered 110,000. o Also Korea ranks the $10^{th}$ greenhouse gas emission countries of the world (134.9 million TC) which may cause Korean industries to suffer severely during the implementation of United Nations Framework Convention on Climate Change (UNFCCC). o Therefore, the target of the study is to develop a model for the analysis and design of industrial complex by integration of the energy usage and environmental problems. o The research work contents are as followings: -Analysis of Korea energy consumption -Concept of the integration of energy and environment problems - Basic concept of industrial complex planning - Case study (1) - Recommendation and conclusion

• Journal of Energy Engineering
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• v.9 no.1
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• pp.47-53
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• 2000

This paper is to propose the concept and performance of a gravity engine which could extract energy from sea or river as a clean. renewable and sustainable power. the vertical motion of the buoyancy cylinder of the present gravity engine is converted to the mechanical work directly without any hydraulic loss. The positive net energy between the imposed and harnessed one is achieved by the specific operating procedure. The detailed derivation of the energy balance is made based on the first principle of thermodynamics. The calculation demonstrates that the present gravity engine could harness more energy than the conventional turbine system in the same basin area because of the relatively high efficiency in the energy conversion system and added mass from the buoyancy cylinder.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.231-236
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• 1999

This paper is to propose a concept and performance of the gravity engine which could extract energy from sea or river as a clean and renewable and sustainable power, the tidal or hydro-power. The vertical motion of the buoyancy cylinder of the present gravity engine is converted to the mechanical work directly without any hydraulic loss. The increased gravity potential during high tide is harnessed proportional to the length of the buoyancy cylinder times tidal height which is greater than the conventional tidal power using water mill. This energy amplification results from the net energy gain between the resource energy and the imposed energy to extract water out of the buoyancy cylinder. Its efficiency is higher than the conventional water mill due to its direct mechanical conversion.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.11-18
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• 2023

This study explores a new energy partitioning approach to determine the fracture toughness of 3-D printed pristine/recycled high density polyethylene (HDPE) blends employing the essential work of fracture (EWF) concept. The traditional EWF approach conducts a uniaxial tensile test with double-edge notched tensile (DENT) specimens and measures the total energy defined by the area under a load-displacement curve until failure. The approach assumes that the entire total energy contributes to the fracture process only. This assumption is generally true for extruded polymers that fracture occurs in a material body. In contrast to the traditional extrusion manufacturing process, the current 3-D printing technique employs fused deposition modeling (FDM) that produces layer-by-layer structured specimens. This type of specimen tends to include separation energy even after the complete failure of specimens when the fracture test is conducted. The separation is not relevant to the fracture process, and the raw experimental data are likely to possess random variation or noise during fracture testing. Therefore, the current EWF approach may not be suitable for the fracture characterization of 3-D printed specimens. This paper proposed a new energy partitioning approach to exclude the irrelevant energy of the specimens caused by their intrinsic structural issues. The approach determined the energy partitioning location based on experimental data and observations. Results prove that the new approach provided more consistent results with a higher coefficient of correlation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1573-1581
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• 2004

Thermodynamic principles are described with a new point of view. In present study, the interaction between two systems is focused instead of the behavior of a system in conventional thermodynamics. The state change of a system cannot occur by itself but it is the result of the interaction between systems. However, the interaction itself is also the result of another kind of interaction, the interaction between two interactions. To reconstruct thermodynamics with such a point of view, the reversible world is imagined, in which conservations and measurements are discussed. There exists a conserved quantity for each mode of reversible interaction. The conserved transferring quantity in the interaction between interactions is the effective work, which is supposed to be measurable and conserved in reversible world. Effective work is the primary concepts of energy. It is the key factor to explain measurements, energy conservation and energy dissipation. The concepts developed in reversible world are applied to the real world in which irreversible phenomena may occur. Irreversibility is the result of effective energy dissipation, in which effective work irreversibly changes into entropy. A quantitative relation between the disappearing effective work and the generated entropy is dissipation equation which is given by experiments. A special temperature scale to give a very simple type of the dissipation equation is the absolute temperature scale, which gives the conventional conservation of energy.

• Women's Health Nursing
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• v.9 no.1
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• pp.61-69
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• 2003

Fatigue is a universally common word. The subject has been studied in different disciplines, but the basic concept of the term still remains unidentified. It becomes especially important for the medical communications between nurses and clients. Based on the framework outlined by Walker and Avant (1995), this analysis attempts to clarify and examine the symptoms of fatigue. The attributes of fatigue identified in this paper were exhaustion, weighted psychological burden, shortage in capacity or lack of energy, shortage incapacity(motivation and excitement), and imbalance of energy. Therefore, the definition of fatigue refers to a subjective feeling from various internal or external stresses. The consequences of fatigue bring reduced capacity and imbalance of energy. The symptoms show a homeostatic disability or shortage of capacity (physical, psychological, environmental and physiological factors). A precise understanding of "fatigue" will be utilized in defining the causes and measuring outcomes. Also, it will enhance the effective medical communications with client s and nurses. In conclusion, more work is needed to develop objective measurement and effect ivenursing intervention.

• Journal of the Korean Chemical Society
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• v.65 no.2
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• pp.145-150
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• 2021

The present study describes a hands-on experiment to help students understand the concept of phase change or phase transition and its application in a phase change material (PCM). PCMs are substances that have the capability of storing and releasing large amounts of thermal energy. They act as energy storage materials that provide an effective way to save energy by reducing the electricity required for heating and cooling. Lauric acid (LA) was selected as an example of the PCM. Students investigated the temperature change of LA and the temperature (of air) inside the test tube. The differences in the temperatures of the systems helped students understand how PCMs work. A one-group pretest and posttest design was implemented with 34 grade-11 students in science and mathematics. Students' understanding was assessed using a multiple-choice test and a questionnaire. The findings revealed that the designed activity helped students understand the concept of phase change and its application to materials for thermal energy storage.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.251-256
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• 2004

A concept in which laser-sustained plasmas (LSPs) are combined with inductively coupled plasmas (ICPs) is proposed. The concept is aiming at extensions of operative conditions of a CW laser thruster due to the fact that the ICP has some characteristics which are in contrast to those of LSPs. An estimation confirmed that the concept would effectively work. And a fundamental experiment was conducted. The results showed that the radio frequency magnetic field induced by a alternate current of 13.56 MHz coupled inductively with LSPs, resulting in the enlargement of the plasma region and the attainment of the enthalpy. It is expected that some improvements will enable to transfer the RF power to the work gas more effectively and to demonstrate the synergy effect between the LSPs and the ICPs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.6
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• pp.832-839
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• 1998

The potential work is defined as the maximum available work extractable from a composite system. It is important concept to understand the behavior of a composite system because it is a property of the composite system and shows the possible room for the system to change its state by itself. To explain this concept quantitatively, the behavior of a composite system composed of two simple ideal gas systems is analyzed. The potential work of the composite system is estimated, the various reversible processes from a given state to the equilibrium state and the processes on which potential works are constant are shown on the T-P and S-V planes. Such an effort will be necessary to understand and characteristics of composite systems as well as helpful for a deeper comprehension of the energy conversion principles.