• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2288-2297
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• 2023

Current designs of both large reactor units and small modular reactors utilize a nuclear fuel with increasing enrichment. This increasing demand for better nuclear fuel utilization is a challenge for nuclear fuel handling facilities. The operation with higher enriched fuels leads to reduced reserves to legislative and safety criticality limits of spent fuel transport, storage and final disposal facilities. Design changes in these facilities are restricted due to a boron content in steel and aluminum alloys that are limited by rolling, extrusion, welding and other manufacturing processes. One possible solution for spent fuel pools and casks is the burnup credit method that allows decreasing very high safety margins associated with the fresh fuel assumption in spent fuel facilities. This solution can be supplemented or replaced by an alternative solution based on placing the neutron absorber material directly into the fuel assembly, where its efficiency is higher than between fuel assemblies. A neutron absorber permanently fixed in guide tubes decreases system reactivity more efficiently than absorber sheets between the fuel assemblies. The paper summarizes possibilities of fixed neutron absorbers for various nuclear fuel and fuel handling facilities. Moreover, an absorber material was optimized to propose alternative options to boron. Multiple effective absorbers that do not require steel or aluminum alloy compatibility are discussed because fixed absorbers are placed inside zirconium or steel cladding.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.507-512
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• 2023

The traditional oviposition ground for indoor breeding of Luciola lateralis is moss. This study was conducted to find the most suitable alternative oviposition ground that can maintain or increase the oviposition rate of L. lateralis while addressing the problems of larva collection time and larva loss that occur when moss is used. As alternative candidate oviposition ground comprising six colors of non-woven fabric and felt were used to measure the fecundity variation rate of L. lateralis with respect to the color and material of the oviposition ground. In addition, measure the fecundity variation rate of L. lateralis in moss, a traditional oviposition ground, was also measured and investigated for comparison. The investigation showed that the average number of eggs in the non-woven fabric group was higher than that in the felt group. The yellow non-woven fabric had an average number of eggs that was more than 100 times higher than of moss used as a traditional oviposition ground. In the space where the six color non-woven fabric were together, L. lateralis concentrated its oviposition on yellow. These results showed that yellow non-woven fabric can be sufficiently used for efficient indoor mass breeding of L. lateralis while addressing problems caused by moss, a traditional oviposition ground.

• Structural Engineering and Mechanics
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• v.37 no.2
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• pp.197-213
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• 2011

Concrete is a heterogeneous material exhibiting quasi-brittle behaviour. While homogenization of concrete is commonly accepted in general engineering applications, a detailed description of the material heterogeneity using a mesoscale model becomes desirable and even necessary for problems where drastic spatial and time variation of the stress and strain is involved, for example in the analysis of local damages under impact, shock or blast load. A mesoscale model can also assist in an investigation into the underlying mechanisms affecting the bulk material behaviour under various stress conditions. Extending from existing mesoscale model studies, where use is often made of specialized codes with limited capability in the material description and numerical solutions, this paper presents a mesoscale computational model developed under a general-purpose finite element environment. The aim is to facilitate the utilization of sophisticated material descriptions (e.g., pressure and rate dependency) and advanced numerical solvers to suit a broad range of applications, including high impulsive dynamic analysis. The whole procedure encompasses a module for the generation of concrete mesoscale structure; a process for the generation of the FE mesh, considering two alternative schemes for the interface transition zone (ITZ); and the nonlinear analysis of the mesoscale FE model with an explicit time integration approach. The development of the model and various associated computational considerations are discussed in this paper (Part 1). Further numerical studies using the mesoscale model for both quasi-static and dynamic loadings will be presented in the companion paper (Part 2).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.45-49
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• 2001

We have investigated physical and electrical properties of the Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin film for alternative gate dielectrics in the metal-oxide-semiconductor device. The oxidation of Hf deposited directly on the Si substrate results in the H $f_{x}$/ $O_{y}$ interfacial layer and the high-k Hf $O_2$film simultaneously. Interestingly, the post-oxidation N2 annealing of the H102/H1Si70y thin films reduces(increases) the thickness of an amorphous HfS $i_{x}$/ $O_{y}$ layer(Hf $O_2$ layer). This phenomenon causes the increase of the effective dielectric constant, while maintaining the excellent interfacial properties. The hysteresis window in C-V curves and the midgap interface state density( $D_{itm}$) of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin films less than 10 mV and ~3$\times$10$^{11}$ c $m^{-2}$ -eV without post-metallization annealing, respectively. The leakage current was also low (1$\times$10-s A/c $m^2$ at $V_{g}$ = +2 V). It is believed that these excellent results were obtained due to existence of the amorphous HfS $i_{x}$/ $O_{y}$ buffer layer. We also investigated the charge trapping characteristics using Fowler-Nordheim electron injection: We found that the degradation of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ gate oxides is more severe when electrons were injected from the gate electrode.e electrode.e.e electrode.e.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.733-738
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• 2017

In this study, we selected chlorine, a typical toxic material used in many workplaces, as the leakage material, and through the analysis of alternative scenarios based on the meteorological conditions in the summer frequently encountered in accidents, we suggest ways to improve the (method of analysis/accident scenario modeling). The analysis of 296 chemical accidents from January 2014 to December 2016 found that the highest rate of occurrence was in summer, accounting for 35.81% of the total. According to the risk assessment, the influence range and number of inhabitants in the influence area were 712.4 m and 20,090 under the annual mean weather conditions and 796.2 m and 27,143 people under the summer mean weather conditions, respectively. This result implies that, under certain conditions, the range of impacts in the current alternative scenario is incomplete. Therefore, risk assessment systems need to be improved in order to take into consideration the characteristics of each chemical substance.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.107-112
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• 2006

If autogenous nail is lost in nail bed injuries, alternative effective nail bed protection material is questionable in postoperative follow up period. The conventional modality with autogenous nail coverage have several disadvantages such as drawback of maintenance, higher chance of loss and complex dressing step (eg. ointment apply for humidification and nail fixation using tape or bandage). So, we have studied the usefulness of adhesive silicone gel sheet for alternative nail bed protection material until the end of nail regeneration. From March 2003 to July 2004, we have experienced 215 traumatic nail bed injuries except fingertip loss. Among these patient, we classified two groups, 30 cases with autogenous nail protection(Group I) and 30 cases with adhesive silicone gel sheet protection(Group II). Mean full nail growth time was 3.6 months in group I and 3.8 months in group II. Mean final nail appearance score(0: poor, 4: excellent) was 3.0 in group I and 3.5 in group II. Adhesive silicone gel sheet protection(Group II) was slightly superior to the autogenous nail protection in final appearance, especially sterile matrix laceration. In conclusion, we believe that adhesive silicone gel sheet application is a simple, acceptable, alternative method for protecting nail bed with loss of autogenous nail. It has a number of advantages compared with autogenous nail such as better humidification, controllable hygiene, less pain, less hospitalization, less frequent visit, less chance of loss, avoiding complex dressing step and more even pressure with adhesiveness, flexibility and durability.

• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.85-91
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• 2010

As enormous construction projects of land development are carried out around Korea, useful construction materials are needed to perform the construction projects. However, there are no more enough of fill and reclamation materials in our country. That is why the coal ash is expected to be utilized as an alternative material. Since the coal ash has the characteristics of a pozzolan and a selfhardening material, it is adjudged that coal ash has a great possibility to be used as a fill and reclamation material. In this study, grain size analysis, Atterberg limit test, and specific gravity test were performed to examine the physical characteristics of the coal ash about a self-hardening material before utilizing the coal ash in the construction. Compaction test, unconfined compression test, direct shear test, and flexible wall permeability test were conducted to investigate the engineering characteristics according to mixture ratios of fly ash and bottom ash. As a result of the tests, it was confirmed that the mixing ratio 1:1 of fly ash and bottom ash is the most effective to use as a fill and reclamation material. If the mixture of coal ash is used as a backfill material with light weight around structure, it is expected to play a significant role in reducing earth pressure on the back of the structure. As the age of the mixture of coal ash goes by, it intends to decrease the coefficient of permeability. As described above, the coal ash should be considered as an alternative material of fill and reclamation materials since the result of the tests indicates that the coal ash is suitable to a useful material on the construction design.

• Structural Engineering and Mechanics
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• v.74 no.5
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• pp.671-678
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• 2020

In this work, the dynamic properties of a high performance concrete containing glass powder (GP) was studied. The GP is a new cementitious material obtained by recycling waste glass presenting pozzolanic activity. This eco-friendly material was incorporated in concrete mixes by replacing 20 and 30% of cement. The mechanical properties of building materials highly affect the response of the structure under dynamic actions. First, the resonant vibration frequencies were measured on concrete plate with free boundary conditions after 14, 28 and 90 curing days by using an alternative vibration monitoring technique. This technique measures the average frequencies of several excitations done at different points of the plate. This approach takes into account the heterogeneity of a material like concrete. So, the results should be more precise and reliable. For measuring the bending and torsion resonant frequencies, as well as the damping ratio. The dynamic properties of material such as dynamic elastic modulus and dynamic shear modulus were determined by modelling the plate on the finite element software ANSYS. Also, the instantaneous aroused frequency method and ultrasound method were used to determine the dynamic elastic modulus for comparison purpose, with the results obtained from vibration monitoring technique.

• Earthquakes and Structures
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• v.14 no.2
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• pp.117-128
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• 2018

In this research work, free vibrations of simply supported functionally graded plate resting on a Winkler-Pasternak elastic foundation are investigated by a new shear deformation theory. The influence of alternative micromechanical models on the macroscopic behavior of a functionally graded plate based on shear-deformation plate theories is examined. Several micromechanical models are tested to obtain the effective material properties of a two-phase particle composite as a function of the volume fraction of particles which continuously varies through the thickness of a functionally graded plate. Present theory exactly satisfies stress boundary conditions on the top and the bottom of the plate. The energy functional of the system is obtained using Hamilton's principle. The closed form solutions are obtained by using Navier technique, and then fundamental frequencies are found by solving the results of eigenvalue problems. Finally, the numerical results are provided to reveal the effect of explicit micromechanical models on natural fundamental frequencies.

• Journal of the Korean Society of Costume
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• v.63 no.8
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• pp.143-155
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• 2013

The outdoor apparel market has been growing very fast recently, and consumers are spending more time doing outdoor activities for their leisure. As the outdoor apparel market is growing, it has started to combine functionality with style to provide more diverse designs and colors for all ages. The increase of interest in heathy life-styles, outdoor activities, and leisure has lead to a rise in demand for outdoor apparel. Now outdoor apparel have become a part of people's daily casual wear in addition to being worn for outdoor activities. This study is focused on a outdoor jacket design which is used as down-alternative material and the purpose of this study is to design outdoor jackets using a down-alternative fabrics that improve the thermal and lightweight effects for clothing comfort, and increase the satisfaction of wearing down-alterative outdoor jacket. The research of this paper was done by using a questionnaire survey. The survey was used to examine the male customers' outdoor activities, purchase behaviors, place, expense and design preferences. Then, down-like fabric was used to make the prototype down jacket and its design, function, and satisfaction with wearing compared with other brands down jacket products were analyzed. Although duck down fabrics are representative of outdoor jackets, they have many problems that need to be solved such as feathers falling out or its vulnerability to moisture. They have competitive prices compared to down jackets so down-alternative jackets are able to gain more proportion of its market share.