• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.71-79
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• 2023

Air ingress incidents are major safety accidents in very-high-temperature reactors (VHTRs). Air containing a high volume fraction of oxygen may cause severe oxidation of core components at the VHTR, especially for the significantly thin alloy tube wall in the intermediate heat exchanger (IHE). The research objects of this study are Inconel 617 and Incoloy 800H, two candidate alloys for IHE in VHTR. The air ingress accident scenario is simulated with high-temperature air flow at 950 ℃. A continuous oxide scale was formed on the surfaces of both the alloys after the experiment. Because the oxide scale of Inconel 617 has a loose structure, whereas that of Incoloy 800H is denser, Inconel 617 exhibited significantly more severe internal oxidation than Incoloy 800H. Further, Inconel 617 showed a significant decrease in ultimate tensile strength and plasticity after aging for 200 h, whereas Incoloy 800H maintained its tensile properties satisfactorily. Through control experiment under vacuum, we preliminarily concluded that serious internal oxidation is the primary reason for the decline in the tensile properties of Inconel 617.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.127-131
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• 1993

A new learning method of both NNI and NNC by which the NNI identifies precisely the dynamic characteristics of the plant is proposed. For control of ihe nonlinear plant we use two neural networks, one -for identification and the other for control. We define a closed loop en-or which depends on identification and control error. In the proposed learning method, the closed loop en-or is utilized to train the NNI and the NNC. Computer simulation results reveal that the NNC based on proposed method is insensitive to variations of the plant parameters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.161-164
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• 2001

In this paper, we investigated the dielectric and piezoelectric properties of Pb(Sb, Nb)O$_3$-Pb(Zr, Ti)O$_3$ ceramic(PSN) for piezoelectric transformer and actuator etc. Effect of MnO$_2$ addition on the PSN ceramic was investigated. Anisotropic properties of electromechanical coupling factor and piezoelectric properties proved to be varied with amount of MnO$_2$ impurity and sintering temperature. The electromechanical coupling factor k$_{p}$ of 0.38 and the mechanical quality factor Q$_{m}$ of 1944 were obtained from the specimen with 0.4 wt% MnO$_2$ sintered at 115$0^{\circ}C$ addition. Experimental results indicated that the PSN ceramic with MnO$_2$ impurity can be effectively used for piezoelectric transformer and actuator.tor.

• Resources Recycling
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• v.7 no.1
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• pp.41-49
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• 1998

This papcr covcrs ihe recovery process of aluminum coagulant by acidic exlraclion which can develop the dewaterability'of residual sludge solids and ihc reduclion ot sludge valumc and mass. Simultmeously, variables affecting acidic extaction of aluminum arc discussed It is represented that the characteristics of recovcrcd coagulant is assessed mth rcspcct to aluminum content. coagulalion effeaiveness, and trace contaminants. The treatment methods of residual sludge solid following acidic extraction arc also d~scussed. Fillally, we suggest some cases in which the results from laboratory can he applied to the fullscale operation and future domestic mosoect of it.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.603-606
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• 2004

Aspects of PD occurrence from PD sources are different with their physical and structural appearances which cause the variation of electric field distributions of them. This paper have investigated electric field distributions of some kinds of electrode structure by FEM applied analysis program. Numeric analysis is a good method to investigate Ihe electric and magnetic field distribution of partial discharge source. The analysis results were confirmed by real PD occurring situation in the laboratory.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1061-1064
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• 1997

Micro injection molding technology is very important fiw mass product of micro structures or micro parts. And, it is so difficult that the molding technology of micro pole or thin wall(barrier rib) structures with high aspect ratio. In this stud). \vc intend to research on the basic technology of micro wall structure part:< with high aspect ratio by the inject~on moldins method. The mold for esperimenrs with micro multi-square structures was made by L, I(;A process. One square polc's size is 157 157pm. height 50011111. And the distance of each poles is 5011n1. 7'hus. molding products will be for~nctl like as the net structure with thin wall of about 50pn thickness.(aspect ratio 10) Ihrough the e~lxriment. \be obtained the prociuctr of micro multi-square slructure with bout 37.000 cell per a piece. 'Ihe micro injection molding process technolog for thin wall by multi-square structure mold was analy~cd.

• The Journal of Korean Medicine
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• v.26 no.3 s.63
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• pp.74-79
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• 2005

Objectives : The purpose of This study was to find the effect of Jeondo-gan (JDS) on acne. Methods : From December 1, 2003 to January 31, 2004, 11 patients with acne were observed, limited to patients who were teated with JDS for more than three weeks. JDS mined with cold water was used on outbreaks of acne, 15 minutes. 1 time per night, 6 times per week. Results & Conclusions : 3 males and 8 females were treated ever three weeks, The average age was 21.73 years old. Before treatment, ache patients had sparse papules on the forehead. both cheeks, and chin, After treatment over three weeks, nine acne patients changed for ihe better at a rate of $81.8\%$ (mild improved $54.6\%$, improved $18.2\%$, much improved $9\%$)

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.4
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• pp.245-251
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• 1994

We considered that characteristics of SO$_2$, concentration level and relations of the meteorological parameters and high pollution concentration from the data measured 7 air quality continuous monitoring stations during 4 years, from 1990 to 1993 in Pusan. The SO$_2$ concentration level showed decreasing trend yearly, it was maximum in Winter, minimum in Summer. The time of SO$_2$ peak concentration lagged from seashore to land because of break-down of the nocturnal inversion layer and seabreeze. Ihe correlations of daily SO$_2$, value between various air quality continuous monitoring stations were highest between Beomcheondong and Meongryundong, lowest between Daeyeondong and Sinpyeongdong because of difference of air Pollution emission sources characteristic. The meteorological parameters affecting SO$_2$ concentration level were minimum temperature, relative humidity, wind speed and air pressure. The SO$_2$ high pollution($\geq$95ppb) occurred almost in Winter, particulaly in such day showing lower wind speed and higher air pressure. Elementary SO$_2$ high Pollution Predictor were high pressure system and stability of lower atmosphere.

• Korean Journal of Microbiology
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• v.35 no.2
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• pp.169-172
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• 1999

Small-seeded legumes can be cultured enclosed in slant agar tubes if dlese plants are to he used for authenicaiing rhizobia or for enumerating 1-hizobia by the plant-inlection technique. An improved method has been developed with substiluting agar slant lor Korean paper(Har7ji). This method was panicularly useful for legumes with rigid radicle such as Cn.xsin 1mnmame. With this method Bmr!,~li1rzobin,17 sp. stram CN9135 on C nonmne induced root nodules biginning at day 7 of the nodulation period in 6% of the l ~ l a ~ l s , and all of ihe plants nodulated 14 days after inoculation by strain CN9135.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.13 no.2
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• pp.5-7
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• 1977

The sand-eel Ammodytes persona/us GIRARD, one of the important fish species in commercial fishing, is found abundantly around the coast of Korea. The author determined the morphological index of the fish after spawning. The samples were caught by the set-net at Jllmllnjin, located ['I Ihe east coast of Korea. 1. The relation between the total length L and the body weight W is represented as $$ W=O. 00l0114L^{2.7281024} $$ 2 Vertebrae number is represented as 64.597 \ulcorner 1.307