• Journal of Korean Society of Steel Construction
• /
• v.19 no.3
• /
• pp.335-344
• /
• 2007

The steel-concrete composite column (i.e., the SC composite column) supports large-gravity loads and simplifies the installation and removal of the work in pouring the concrete. The column takes advantage of the in-plant prefabrication of steel, the speed of erection of a steel structure, and the fire resistance of steel. This paper presents the results of a parametric study using heat transfer analysis and a P-M interaction curve, and compares these results with the experimental results to check the accuracy of the proposed parametric studies. The parametric studies, such as the study of the concrete ratio of an area and the fire protection thickness, provide information on the fire resistance of SC composite columns.

• Journal of Welding and Joining
• /
• v.2 no.1
• /
• pp.4-17
• /
• 1984

Overlaid weld metals of austenitic stainless steel in a pressure vessel of power reactor are usually post-weld heated for a long period of time after welding. The PWHT is considered as a kind of sensitizing and it is important to check the soundness of the weld metal after PWHT, especially about the precipitation of carbides. The purpose of this report is to obtain information on the relation between the change of microstructure and Post-Weld Heat Treatment in the overlaid weld metals. Metallurgical aspects of the problem on austenitic stainless steel heated at $625^{\circ}C$, $670^{\circ}C$, $720^{\circ}C$ and $760^{\circ}C$ for 3, 10, 30, 100 and 300 hours have been investigated by means of optical-micrography, micro-hardness measurement, scanning electron microscope and electron-probe micro analysis. From the results obtained, the following conclusions are drawn; 1) The PWHT above $625^{\circ}C$ for a long time causes a diffusion of carbon atoms from low alloy steel into stainless steel, and consequently carbon is highly concentrated at the boundary layer of stainless steel. 2) C in ferritic steel migrated to austenitic steel and carbides precipitated in austenitic steel along fusion line. At higher temperatures, the ferrite grains coarsened in the decarburized zone. 3) In the change of microstructure of stainless steel overlaid weld metal, the width of carbides precipitated zone and decarburized zone increased with increase of PWHT temperature and time. 4) At about $625^{\circ}C$ to $760^{\circ}C$, chromium carbides, mainly $M_{23} C_6$, precipitate very closely in the carburized layer with remarkable hardening. 5) Precipitation of delta ferrite from molten weld metal depends on solidification phenomenon. There was a small of ferrite near the bond in which the local solidification time was short, comparing with after parts of weld metal. Shape and amount of ferrite were not changed by Post-Weld Heat Treatment after solidification.

• Atmosphere
• /
• v.24 no.2
• /
• pp.197-206
• /
• 2014

The effects of different averaging operators and atmospheric stability on the turbulent fluxes are investigated using the vertical velocity, air temperature, carbon dioxide concentration, and absolute humidity data measured at 10 Hz by a 3-dimensional sonic anemometer and an open-path $CO_2/H_2O$ infrared gas analyzer installed at a height of 18.5 m on the rooftop of the Jungnang KT building located at a typical residential area in Seoul, Korea. For this purpose, 7 different averaging operators including block average, linear regression, and moving averages during 100 s, 300 s, 600 s, 900 s, and 1800 s are considered and the data quality control procedure such as physical limit check and spike removal is also applied. It is found that as the averaging interval becomes shorter, turbulent fluxes computed by the moving average become smaller and the ratios of turbulent fluxes computed by the 100 s moving average to the fluxes by the 1800 s moving average under unstable stability are smaller than those under neutral stability. The turbulent fluxes computed by the linear regression are 85~92% of those computed by the 1800 s moving average and nearly the same as those computed by 900 s moving average, implying that the adequate selection of an averaging operator and its interval will be very important to estimate more accurate turbulent fluxes at urban area.

• Korean Chemical Engineering Research
• /
• v.57 no.4
• /
• pp.531-538
• /
• 2019

As the performance of PEMFC has been improved, the water and heat generated by reaction have increased so, the water and heat management of PEMFC is becoming more important. In this study, hydrogen recirculation was applied as the water management technique and the effect of recirculation flow rate, purge interval and duration on the performance of PEMFC was investigated. Anode pressure, fuel humidity and utilization, water discharge amount was measured to check the effect of purge conditions on performance. As the recirculation flow rate has increased, the performance of PEMFC became lower due to decrease of anode outlet pressure. According to the purge conditions, instantaneous voltage drop has occurred because of accumulated water. In frequent purge conditions, the performance of PEMFC gradually decreased due to fuel humidity control failure. Stable performance and high fuel utilization was achieved on this work by analyzing the effect of purge conditions.

• Journal of Drive and Control
• /
• v.18 no.1
• /
• pp.1-8
• /
• 2021

This paper presents research on methods for the reduction of forklifts' noise level for the increased comfort and safety of its operator. A cooling fan with a high air volume flow rate installed in the forklift acts as an important design parameter which efficiently cools the heat exchanger system, helping to transfer internal heat from the engine room to the outdoors with both transmitted and diffracted opening noises. The cooling fan contributes significantly to both the forklift's emitted sound power and the operator room's noise level, thereby necessitating research on the forklift's reduction of acoustic power level and transmission. A noise analysis for various fan models with a biomimetic design based on eagle-wing geometry was conducted. In addition to the acoustic power generation, the aerodynamic performance of the cooling blade is also strongly influenced by the design of airfoil distribution, thereby requiring optimization. The cooling fans were fabricated and installed in the forklift in order to check the efficacy of the forklift engine's cooling, and the final version of the fan was measured for its ability to lower acoustic power level and cool the engine room. This study explains the aerodynamic and acoustic features of the designed fans with the use of BEM analysis and forklift test results.

• Composite Materials and Engineering
• /
• v.3 no.3
• /
• pp.167-178
• /
• 2021

In the present paper, the destructive behavior of distilled water, salty water, sulfuric acid, and heat on glass/vinyl ester composites was investigated by experimental methods. Hetron 922 vinyl ester resin and two types of mat and woven glass fibers as the reinforcements were used to fabricate composite test samples. All samples were immersed in distilled water, salty water, and sulfuric acid with three different concentrations. The tests were performed at 20℃ and 70℃ for the exposure duration of 1, 2, 4, and 8 weeks. Bending tests were performed after aging for all composite samples to check the degradation of the bending modulus and strength. The results show that the effect of distilled water, in comparison with salty water, on the degradation of composite samples was significant. On the other hand, almost non-sensitivity of concentrations of salty water on the weight gain of specimens has been observed. In addition, it was also observed that the degradation of samples at 70℃ temperature is much more than that of at 20℃. Also, it was observed that the flexural modulus of virgin specimens exposed to salty water (2% concentration) has been recovered just after two weeks of immersion. Furthermore, in some cases, composite samples under the sulfuric acid solution have lost almost 80% of their mechanical properties.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.15 no.2
• /
• pp.271-288
• /
• 2002

Authors investigated the pathogenesis and treatment of dennatosurgical diseases in the ImJeungJiNamUiAn(臨證指南醫案). 1. The symptoms and diseases of dermatosurgery were as follows; 1) BanSaJinRa(반사진라) : eczema, atopic dermatitis, seborrheic dermatitis, psoriasis, lichen planus, pityriasis rosea, hives, dermographism, angioedema, cholinergic urticaria, urticaria pigmentosa, acne, milium, syringoma, keratosis pilaris, discoid lupus erythematosus, hypersensitivity vasculitis, drug eruption, polymorphic light eruption, rheumatic fever, juvenile rheumatoid arthritis(Still's disease), acute febrile neutrophilic dermatosis(Sweet's syndrome), Paget's disease, folliculitis, viral exanthems, molluscum contagiosum, tinea, tinea versicolor, lymphoma, lymphadenitis, lymphangitis, granuloma annulare, cherry angioma 2) ChangYang(瘡瘍) : acute stage eczema, seborrheic dermatitis, stasis ulcer, intertrigo, xerosis, psoriasis, lichen planus, ichthyosis, pityriasis rosea, rosacea, acne, keratosis pilaris, dyshidrosis, dermatitis herpetiformis, herpes gestationis, bullae in diabetics, pemphigus, lupus erythematosus, fixed drug eruption, erythema multiforme, toxic epidermal necrolysis, toxic shock syndrome, staphylococcal scaled skin syndrome, scarlet fever, folliculitis, impetigo, pyoderma gangrenosum, tinea, candidiasis, scabies, herpes simplex, herpes zoster, chicken pox, Kawasaki syndrome, lipoma, goiter, thyroid nodule, thyroiditis, hyperthyroidism, thyroid cancer, benign breast disorder, breast carcinoma, hepatic abscess, appendicitis, hemorrhoid 3) Yeok(疫) : scarlet fever, chicken pox, measles, rubella, exanthem subitum, erythema infectiosum, Epstein-Barr virus infection, cytomegalovirus infection, hand-foot-mouth disease, Kawasaki disease 4) Han(汗) : hyperhidrosis 2. The pathogenesis and treatment of dermatosurgery were as follows; 1) When the pathogenesis of BalSa(발사), BalJin(發疹), BalLa(발라) and HangJong(項腫) are wind-warm(風溫), exogenous cold with endogenous heat(外寒內熱), wind-damp(風濕), the treatment of evaporation(解表) with Menthae Herba(薄荷), Arctii Fructus(牛蒡子), Forsythiae Fructus(連翹) Mori Cortex(桑白皮), Fritillariae Cirrhosae Bulbus(貝母), Armeniaoae Amarum Semen(杏仁), Ephedrae Herba(麻黃), Cinnamomi Ramulus(桂枝), Curcumae Longae Rhizoma(薑黃), etc can be applied. 2) When the pathogenesis of BuYang(부양), ChangI(瘡痍) and ChangJilGaeSeon(瘡疾疥癬) are wind-heat(風熱), blood fever with wind transformation(血熱風動), wind-damp(風濕), the treatment of wind-dispelling(疏風) with Arctii Fructus(牛蒡子), Schizonepetae Herba(荊芥), Ledebouriellae Radix(防風), Dictamni Radicis Cortex(白鮮皮), Bombyx Batrytioatus(白？?), etc can be applied. 3) When the pathogenesis of SaHuHaeSu(사후해수), SaJin(사진), BalJin(發疹), EunJin(은진) and BuYang(부양) are wind-heat(風熱), exogenous cold with endogenous heat(外寒內熱), exogenous warm pathogen with endogenous damp-heat(溫邪外感 濕熱內蘊), warm pathogen's penetration(溫邪內陷), insidious heat's penetration of pericardium(伏熱入包絡), the treatment of Ki-cooling(淸氣) with TongSeongHwan(通聖丸), Praeparatum(豆？), Phyllostachys Folium(竹葉), Mori Cortex(桑白皮), Tetrapanacis Medulla(通草), etc can be applied. 4) When the pathogenesis of JeokBan(적반), BalLa(발라), GuChang(久瘡), GyeolHaek(結核), DamHaek(痰核), Yeong(？), YuJu(流注), Breast Diseases(乳房疾患) and DoHan(盜汗) are stagnancy's injury of Ki and blood(鬱傷氣血), gallbladder fire with stomach damp(膽火胃濕), deficiency of Yin in stomach with Kwolum's check (胃陰虛 厥陰乘), heat's penetration of blood collaterals with disharmony of liver and stomach(熱入血絡 肝胃不和), insidious pathogen in Kwolum(邪伏厥陰), the treatment of mediation(和解) with Prunellae Spica(夏枯草), Chrysanthemi Flos(菊花), Mori Folium (桑葉), Bupleuri Radix(柴胡), Coptidis Rhizoma(黃連), Scutellariae Radix(黃芩), Gardeniae Fructus(梔子), Cyperi Rhizoma(香附子), Toosendan Fructus(川？子), Curcumae Radix(鬱金), Moutan Cortex(牧丹皮), Paeoniae Radix Rubra(赤芍藥), Unoariae Ramulus Et Uncus(釣鉤藤), Cinnamorni Ramulus(桂枝), Paeoniae Radix Alba(白芍藥), Polygoni Multiflori Radix (何首烏), Cannabis Fructus (胡麻子), Ostreae Concha(牡蠣), Zizyphi Spinosae Semen(酸棗仁), Pinelliae Rhizoma(半夏), Poria(백복령). etc can be applied. 5) When the pathogenesis of BanJin(반진), BalLa(발라), ChangI(瘡痍), NamgChang(膿瘡). ChangJilGaeSeon(瘡疾疥癬), ChangYang(瘡瘍), SeoYang(署瘍), NongYang(膿瘍) and GweYang(潰瘍) are wind-damp(風濕), summer heat-damp(暑濕), damp-warm(濕溫), downward flow of damp-heat(濕熱下垂), damp-heat with phlegm transformation(濕熱化痰), gallbladder fire with stomach damp(膽火胃濕), overdose of cold herbs(寒凉之樂 過服), the treatment of damp-resolving(化濕) with Pinelliae Rhizoma(半夏), armeniacae Amarum Semen(杏仁), Arecae Pericarpium(大腹皮), Poria(백복령), Coicis Semen(薏苡仁), Talcum(滑石), Glauberitum(寒水石), Dioscoreae Tokoro Rhizoma(？？), Alismatis Rhizoma(澤瀉), Phellodendri Cortex(黃柏), Phaseoli Radiati Semen(？豆皮), Bombycis Excrementum(?沙), Bombyx Batryticatus(白？?), Stephaniae Tetrandrae Radix(防己), etc can be applied. 6) When the pathogenesis of ChangPo(瘡泡), hepatic abscess(肝癰) and appendicitis(腸癰) are food poisoning(食物中毒), Ki obstruction & blood stasis in the interior(기비혈어재과), damp-heat stagnation with six Bu organs suspension(濕熱結聚 六腑不通), the treatment of purgation(通下) with DaeHwangMokDanPiTang(大黃牧丹皮湯), Manitis Squama(穿山甲), Curcumae Radix(鬱金), Curcumae Longae Rhizoma(薑黃), Tetrapanacis Medulla(通草), etc can be applied. 7) When the pathogenesis of JeokBan(적반), BanJin(반진), EunJin(은진). BuYang(부양), ChangI(瘡痍), ChangPo(瘡泡), GuChang(久瘡), NongYang(膿瘍), GweYang(潰瘍), Jeong(정), Jeol(癤), YeokRyeo(疫？) and YeokRyeolpDan(疫？入？) are wind-heat stagnation(風熱久未解), blood fever in Yangmyong(陽明血熱), blood fever with transformation(血熱風動), heat's penetration of blood collaterals(熱入血絡). fever in blood(血分有熱), insidious heat in triple energizer(三焦伏熱), pathogen's penetration of pericardium(心包受邪), deficiency of Yong(營虛), epidemic pathogen(感受穢濁), the treatment of Yong & blood-cooling(淸營凉血) with SeoGakJiHwangTang(犀角地黃湯), Scrophulariae Radix(玄參), Salviae Miltiorrhizae Radix(丹參), Angelicae Gigantis Radix(當歸), Polygoni Multiflori Radix(何首烏), Cannabis Fructus(胡麻子), Biotae Semen(柏子仁), Liriopis Tuber(麥門冬), Phaseoli Semen(赤豆皮), Forsythiae Fructus(連翹), SaJin(사진), YangDok(瘍毒) and YeokRyeoIpDan(역려입단) are insidious heat's penetration of pericardium(伏熱入包絡), damp-warm's penetration of blood collaterals(濕溫入血絡), epidemic pathogen's penetration of pericardium(심포감수역려), the treatment of resuscitation(開竅) with JiBoDan(至寶丹), UHwangHwan(牛黃丸), Forsythiae Fructus(連翹), Curcumae Radix(鬱金), Tetrapanacis Medulla(通草), Acori Graminei Rhizoma(石菖蒲), etc can be applied. 9) When the pathogenesis of SaHuSinTong(사후신통), SaHuYeolBuJi(사후열부지), ChangI(瘡痍), YangSon(瘍損) and DoHan(盜汗) are deficiency of Yin in Yangmyong stomach(陽明胃陰虛), deficiency of Yin(陰虛), the treatment of Yin-replenishing(滋陰) with MaekMunDongTang(麥門冬湯), GyeongOkGo(瓊玉膏), Schizandrae Fructus(五味子), Adenophorae Radix(沙參), Lycii Radicis Cortex (地骨皮), Polygonati Odorati Rhizoma(玉竹), Dindrobii Herba(石斛), Paeoniae Radix Alba(白芍藥), Ligustri Lucidi Fructus (女貞子), etc can be applied. 10) When the pathogenesis of RuYang(漏瘍) is endogenous wind in Yang collaterals(陽絡內風), the treatment of endogenous wind-calming(息風) with Mume Fructus(烏梅), Paeoniae Radix Alba (白芍藥), etc be applied. 11) When the pathogenesis of GuChang(久瘡), GweYang(潰瘍), RuYang(漏瘍), ChiChang(痔瘡), JaHan(自汗) and OSimHan(五心汗) are consumption of stomach(胃損), consumption of Ki & blood(氣血耗盡), overexertion of heart vitality(勞傷心神), deficiency of Yong(營虛), deficiency of Wi(衛虛), deficiency of Yang(陽虛), the treatment of Yang-restoring & exhaustion-arresting(回陽固脫) with RijungTang(理中湯), jinMuTang(眞武湯), SaengMaekSaGunjaTang(生脈四君子湯), Astragali Radix (황기), Ledebouriellae Radix(防風), Cinnamomi Ramulus(桂枝), Angelicae Gigantis Radix(當歸), Ostreae Concha(牡蠣), Zanthoxyli Fructus(川椒), Cuscutae Semen(兎絲子), etc can be applied.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.11 no.2
• /
• pp.51-60
• /
• 2003

In the nuclear power plant, emergency core coolant system (ECCS) is furnished at reactor coolant system (RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, thermal stratification phenomenon can occur due to coolant leaking in the check valve. The thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue crack (TFC) accident. In the present study, effects of turbulence penetration on the thermal stratification into T-branches with square cross-section in the modeled ECCS are analysed numerically. Standard k-$\varepsilon$ model is employed to calculate the Reynolds stresses in momentum equations. Results show that the length and strength of thermal stratification are primarily affected by the leak flow rate of coolant and the Reynolds number of duct. Turbulence penetration into the T-branch of ECCS shows two counteracting effects on the thermal stratification. Heat transport by turbulence penetration from main duct to leaking flow region may enhance thermal stratification while the turbulent diffusion may weaken it.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2309-2314
• /
• 2007

The application analysis of bubble pump on the domestic solar water heater system is presented. The system investigated in this study is a passive device, self pumping and self regulating. It was test to use the bubble pump on solar water heater system. The test experiment has been taken on the existed vacuum tube about the efficiency, working fluid temperature and pressure and circulated power. In order to check the working temperature and working pressure effectively, the bubble pump was test separated from the solar water heater. The equipment consists of the bubble pump, heater and heat exchanger. The main structure of bubble pump was design depend on the character of two phase flow. The complete system was instrumented to measure pressures, temperatures and flow-rates at various locations. The theory analysis of design bubble pump has been given and the experiment design has been included in the paper.

• Journal of the Society of Naval Architects of Korea
• /
• v.49 no.3
• /
• pp.222-226
• /
• 2012

When ship blocks are erected or pre-erected, most blocks will be at outdoors where they are not protected from weather and exposed to ray of the sun. A deck plate compared to those in radiation heat transfer from the sun will have higher temperature than it of ambient air, and will expand more than lower laying structures whose temperatures are similar with air. But deck plates and under-structures are connected, so the deck plate will be under out-of-plane deformation rather than expand in length. In this study, we considered the temperature difference between air and plate as a major parameter of out-of-plane deformation, and analyzed how much additional deformation would take place. In addition, when a deformation could take place was also analyzed based on the initial deformed shape of deck plate. Because the accuracy inspections of deck plate will be done during daytime, conventional accuracy check results on sunny day could make us feel unfair. Thus resonable datum about momentary additional out-of-plane deformation due to environmental effects have been determined. The real deformation values can be specified even under enlarged deformations by radiation-expansion.