• 산업경영시스템학회지
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• 제44권3호
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• pp.117-124
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• 2021

The development of IOT technology and artificial intelligence technology is promoting the smartization of manufacturing system. In this study, data extracted from acceleration sensor and current sensor were obtained through experiments in the cutting process of SKD11, which is widely used as a material for special mold steel, and the amount of tool wear and product surface roughness were measured. SVR (Support Vector Regression) is applied to predict the roughness of the product surface in real time using the obtained data. SVR, a machine learning technique, is widely used for linear and non-linear prediction using the concept of kernel. In particular, by applying GSVQR (Generalized Support Vector Quantile Regression), overestimation, underestimation, and neutral estimation of product surface roughness are performed and compared. Furthermore, surface roughness is predicted using the linear kernel and the RBF kernel. In terms of accuracy, the results of the RBF kernel are better than those of the linear kernel. Since it is difficult to predict the amount of tool wear in real time, the product surface roughness is predicted with acceleration and current data excluding the amount of tool wear. In terms of accuracy, the results of excluding the amount of tool wear were not significantly different from those including the amount of tool wear.

• Journal of Advanced Marine Engineering and Technology
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• 제29권5호
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• pp.495-501
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• 2005

Al is a active metal that owes its resistance to a thin, protective, barrier oxide surface layer, which is stable in air and neutral aqueous solution. Thus Al alloys are widely used in architectural trim. cold & hot-water storage vessels and piping. However Al and most of its alloy may corrode with some forms such as pitting corrosion, intergranular corrosion and galvanic corrosion in the case of exposure to various industrial and marine atmosphere. Therefore a correct evaluation of corrosion resistance for their Al and Al alloys may be more important in a economical point of view. In this study. a relative evaluation of corrosion resistance for three kinds of Al alloys such as ALDC2, ALDC3, and ALDC8 series was carried out with electrochemical method. There is a tendency that corrosion potential is shifted to positive or negative direction by alloying components regardless of corrosion resistance. Moreover the data of corrosion properties obtained from cathodic Polarization curve, cyclic voltammogram and AC. DC impedance respectively showed a good correspondence each other against the corrosion resistance but variation of corrosion potential. passivity current density of anodic polarization curve and corrosion current density by Tafel extrapolation and Stern-Geary method didn't correspond with not only each other but also considerably the data of corrosion properties discussed above. Therefore it is suggested that an optimum electrochemical evaluation for corrosion resistance of Al alloy is to calculate the diffusion limiting current density of cathodic polarization curve, impedance of AC or DC and polarization resistance of cyclic voltammogram.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.59-65
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• 2012

A study on the electrical characteristic analysis of solar cell diodes under experimental conditions of varying temperature and frequency has been conducted. From the current-voltage (I-V) measurements, at the room temperature, we obtained the ideality factor (n) for Space Charge Region (SCR) and Quasi-Neutral Region (QNR) of 3.02 and 1.76, respectively. Characteristics showed that the value of n (at SCR) decreases with rising temperature and n (at QNR) increases with the same conditions. These are due to not only the sharply increased SCR current flow but the activated carrier recombination in the bulk region caused by defects such as contamination, dangling bonds. In addition, from the I-V measurements implemented to confirm the junction uniformity of cells, the average current dispersion was 40.87% and 10.59% at the region of SCR and QNR, respectively. These phenomena were caused by the pyramidal textured junction structure formed to improve the light absorption on the device's front surface, and these affect to the total diode current flow. These defect and textured junction structure will be causes that solar cell diodes have non-ideal electrical characteristics compared with general p-n junction diodes. Also, through the capacitance-voltage (C-V) measurements under the frequency of 180 kHz, we confirmed that the value of built-in potential is 0.63 V.

• 전기학회논문지P
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• 제59권4호
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• pp.434-439
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• 2010

This study fabricated a simulation facility which reduced the structure of a current distribution line to 50:1 in order to analyze the induced lightning shielding effect of a 22.9kV-Y distribution line according to ground resistance capacity, grounding locations, etc. When installing an overhead ground wire, the standard for grounding a distribution line with a current of 22.9kV-Y requires that ground resistance in common use with the neutral line be maintained less than $50\Omega$every 200m span. The reduced line for simulation had 7 electric poles and induced lightning was applied to the ground plane 2m apart from the line in a direction perpendicular to it using an impulse generator. If induced voltage occurred in the line and induced current flowed through the line due to the applied current, the induced voltage and current of the 'A' phase were measured respectively using an oscilloscope. When all 7 electric poles were grounded with a ground resistance of less than $50\Omega$ respectively, the combined resistance of the line was $7.4\Omega$. When an average current of 230A was applied, the average induced voltage and current measured were 1,052V and 13.8A, respectively. Under the same conditions, when the number of grounding locations was reduced, the combined resistance as well as induced voltage and current showed a tendency to increase. When all 7 electric poles were grounded with a ground resistance of less than $100\Omega$, the combined resistance of the line was $14.9\Omega$. When an average current of 236A was applied, the average induced voltage and current of the 'A' phase calculated were 1,068V and 15.6A, respectively. That is, in this case, only the combined resistance was greater than when all 7 electrical poles were grounded, and the induced voltage and current were reduced. Therefore, it is thought that even though ground resistance is slightly higher under a construction environment with the same conditions, it is advantageous to ground all electric poles to ensure system safety.

• 한국지역사회생활과학회지
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• 제21권1호
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• pp.117-124
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• 2010

Recently, research on variables associated with hair styles are increasing with the spreading of total coordinated intention in the fields of clothing and cosmetology. In the present study, we focused on examining the skin temperature on the scalp(the vertex, temporal, and occiput), humidity on the occiput, skin temperatures (the forehead, back of ear, back of neck, upper back, abdomen, forearm, hand, thigh, calf, and foot), rectal temperature, total body mass loss by hair styles in a thermal neutral environment. Four young females participated as subjects. For a certain period, each subject had the five different hair styles in a random order: (1)Straight short hair(SS), (2)Perm waved short hair(PS), (3) Straight long hair(SL), (4)Perm waved long hair(PL), (5)Ponytail style(PT). Subjects wore briefs, bra, shirts with long sleeves, long legged training pants, and socks. The environmental variables of a climatic chamber were kept constant at $21{\pm}0.5^{\circ}C$ of air temperature and 55${\pm}$5%RH of air humidity. The results indicated the following: The skin temperature and humidity on the scalp did not show any significant differences among five different hair styles, but straight long hair style(SL)was the highest on the vertex, temporal, and occiput. The temporal skin temperature($29.8\sim30.8^{\circ}C$) was the highest, while the vertex skin temperature($28.7\sim30.1^{\circ}C$) was the lowest. Humidity on the occiput was the highest in the perm waved long hair style(PL). The back of ear skin temperature was significantly lower in the ponytail style(PT) than in the other four hair styles(p<.001). In the straight long hair style(SL), the skin temperature on the back of the neck and on the upper back were significantly higher than those of the other four hair styles(p<.01). Mean skin temperature and rectal temperature had no significant differences among hair styles. Total body mass was the highest in the perm waved long hair style(PL)(p<.05). We acquired fundamental data to enable the improvement of the current hair clinic system, wigs, functional hats, and helmets.

• 한국문헌정보학회지
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• 제25권
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• pp.265-294
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• 1993

At the present. one of the very important functions of the information center or library is to provide information service on time and to the right person. But it is impossible if the shape of the material is not complete. So it is important to keep the material of information complete. This study is on deacidification of paper materials for enhancing useful life of information. This study can be summerized as follews; The material needs deacidification is all of machine-made paper except neutral paper, and hand made paper which are below pH 6.5. The best way for the deacidification for the small amount of materals is to use aqueous deacidifiers such as Calcium Carbonate, Magnesuim Carbonate and Borax. For mass deacidification process, Methoxy Magnesuim Methyle Carbonate and Magnesuim Oxide, called

• 한국연초학회지
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• 제29권2호
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• pp.110-117
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• 2007

In vitro toxicity tests such as cytotoxicity, mutagenicity and genotoxicity assay are useful for evaluating the relative toxicity of smoke or smoke condensates obtained from different cigarette configurations. A major disadvantage of these tests is relatively time-consuming, complicated and expensive. Recently, a cell-free glutathione consumption assay (GCA) as a rapid and simple screening method for the toxicity assessment of smoke has been reported by Cahours et al. (CORESTA, 2006). This study was carried out to assess the GCA application capable of predicting the toxicity of gas/vapor phase (GVP) of cigarette smoke and to identify individual compounds responsible for the glutathione (GSH) consumption in smoke. Each GVPs from 2R4F, standard cigarette, carbon filter cigarette (ExC) and new carbon filter cigarette (ExN), test cigarettes were collected by automatic smoking machine and evaluated the relative toxicity by GCA and neutral red uptake (NRU) assay. Toxic compounds existed in smoke were also chosen, relative toxicities of these compounds were screened by using two methods and compared individually. The overall order of toxicity by GCA was 2R4F > ExC > ExN, which was consistent with the result of Neutral Red Uptake assay. The levels of carbonyl compounds of ExN were lower than those of 2R4F and ExC, indicating that GSH consumption was associated with carbonyl compound yields. A major toxicant under current study is acrolein, which contributed to more than half of the GSH consumption. Collectively, the toxicity of GVP determined by GCA method may be mainly attributed to acrolein.

• International Journal of Concrete Structures and Materials
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• 제18권1E호
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• pp.11-16
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• 2006

The use of the current ACI 318 stress block parameters has been reported to provide unconservative estimations of the moment capacities for high-strength concrete columns. Accordingly, several concrete stress block parameters have been recently proposed. This paper discusses various concrete stress block parameters for high-strength concrete and their influences on the code provisions. In order to adopt the proposed stress block parameters to the design code, it is necessary to understand the impact of the change of the stress block parameters on various aspects of the code provisions. For this purpose, the influence of using of different stress block parameters on the location of the neutral axis and the tensile strain in extreme tension steel as well as the axial and moment capacities are investigated. In addition, the influence on the prestressed concrete members is also elucididated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1190-1192
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• 2002

These days, electromagnetic radiation noise and switching losses of static converter become harmful. Many resonant inverters with radiation techniques solve their such problems. Auxiliary Resonant Commutated Pole Inverter (ARCP) was proposed. but it has two demerits. In circuit configuration. It isn't constructed by 2 in 1 IGET modules. Besides, control is complicated because of neutral point voltage control and boost current control. This paper proposes a new auxiliary resonant inverter which solved two demerits. In addition, it deals efficiency which compared with hard switching inverter and result of separation of power loss

• 한국CDE학회논문집
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• 제9권2호
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• pp.175-182
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• 2004

As a bridge between design and manufacturing, process planning is to generate a sequenced set of instructions to manufacture the specified part. Automatic interpretation of manufacturing information incorporated in the design documentation such as CAD file has been a knotty subject for manufacturing engineers since no current data exchange format for product data provides a perfect interface between heterogeneous systems. The recent neutral data exchange format STEp, standard for the exchange of product model data, includes not only geometry but also technical and managerial information. STEP AP(Application Protocol) 224 is specifically dedicated to the mechanical product definition for process planning using machining features. Given a design information in STEP AP 224 format, process planning can be made without human intervention. This paper describes a method to determine the sequence of machining features by using the machining features and the manufacturing information expressed in STEP AP224.