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MnS 및 V-탄질화물의 석출이 0.26C-1.5Mn 강의 페라이트 입내 핵생성에 미치는 영향
이상우,박지용,박중근,주웅용 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.11
The effects of manganese sulfide and vanadium carbonitrides on the intragranular ferrite nucleation have been studied by calculating the equilibrium relationship between vanadium carbonitrides and manganese sulfide and by applying controlled cooling rate experiment in 0.26C-1.5Mn steels. Equilibrium calculation shows that there is little interaction between vanadium carbonitrides and MnS. The vanadium nitride forms as a vanadium carbonitride(VC_yN_(1-y)) below about 1100℃ and the carbon composition(y) rises with decreasing temperature. The manganese sulfide is expected to form at above 1500℃, i.e. from liquid phase. Controlled cooling rate experiments showed that MnS particles consist of bimodal size distribution. The relatively fine particles(<5㎛) continuously grow during solid-state cooling and their distribution is influenced by the cooling rate, faster cooling rate favoring ferrite distribution. MnS acts as an important intragranular ferrite nucleation site. Intermediate holding experiments during continuous cooling experiment suggests that Mn depletion around MnS particles is mainly responsible for intragranular ferrite nucleation. In the case of after-heat treatments, MnS particles were believed to act as nucleation site for vanadium carbonitrides, which largely promotes the intragranular ferrite nucleation.
공기공급 시스템에 적용되는 Vortex Tubes 의 에너지 분리특성에 관한 연구(2) : 표면의 단열효과에 따른 영향 the effect of surface insulation
추홍록,유갑종,방창훈 한국산업안전학회 1999 한국안전학회지 Vol.14 No.1
The vortex tube is a simple device which splits a compressed gas stream into a cold stream and a hot stream without any chemical reactions. Recently, vortex tube is widely used to 1ocal cooler of industrial equipments and air supply system. In this study, the insulation effect of surface on the efficiency of vortex tube was performed experimentally. The experiment is carried out for nozzle area ratio of 0.194, diameter ratio of cold end orifice of 0.6 and input pressure ranging from 0.2Mpa to 0.5Mpa. The purpose of this study is focused on the effect of surface insulation of vortex tube with the variation of cold air mass flow ratio. The results indicate that the temperature difference of cold and hot air are higher about 12% and 30% than that of not insulated vortex tube respectively. Furthermore, for the insulated vortex tube, the similarity relation for the prediction of cold end temperature as the function of cold air mass flow ratio and input pressure is obtained.
추홍록,상희선,이병화 한국산업안전학회 1998 한국안전학회지 Vol.13 No.4
The vortex tube is a simple device for separating a compressed gaseous fluid stream into two flows of high and low temperature without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air supply system. The phenomena of energy separation through the vortex tube was investigated experimentally. This study is focused on the effect of the diameter of cold end orifice diameter on the energy separation. The experiment was carried out with various cold end orifice diameter ratio from 0.22 to 0.78 for different input pressure and cold air flow ratio. The experimental results were indicated that there are an optimum diameter of cold end orifice for the best cooling performance. The maximum cold air temperature difference was appeared when the diameter ratio of the cold end orifice was 0.5. The maximum cooling capacity was obtained when the diameter ratio of the cold end orifice was 0.6 and cold air flow ratio was 0.7.
Vortex Tube 의 부분유입율과 저온 입 출구비가 에너지분리 특성에 미치는 영향
김정수,추홍록,상희선 한국산업안전학회 1998 한국안전학회지 Vol.13 No.3
The vortex tube is a simple device for separating a compressed fluid stream into two flows of high and low temperature without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air conditioner for special purpose. The phenomena of energy separation through the vortex tube were investigated to see the effects of cold flow inlet-outlet ratios and partial admission rates on the energy separation experimentally. The experiment was carried out with various cold flow inlet-outlet ratios from 0.28 to 10.56 and partial admission rates from 0.176 to 0.956 by varying input pressure and cold air flow ratio. To find best use in a given cold flow inlet-outlet ratio and partial admission rate, the maximum temperature difference of cold air was presented. The experimental results were indicated that there are an optimum range of cold flow inlet-outlet ratio for each partial admission rate and available partial admission rate.
주웅용,권숙인,홍순택 한국열처리공학회 1999 熱處理工學會誌 Vol.12 No.2
Grain size of steels is one of the most important parameters which influence yield strength and fracture toughness. Ultrasonic wave propagating in polycrystalline materials is mostly attenuated by scattering at grain boundary. Effect of ultrasonic attenuation on average ferrite grain size of carbon steels with tensile strength 40∼60kgf/㎟ consisting of multi phases such as ferrite+pearlite and ferrite+pearlite+bainite was evaluated. The attenuation of these steels rapidly increased with average ferrite grain diameter. Average ferrite grain diameter (D_(av), ㎛) could be expressed as 1.79+22.97* a^(1/2.03), where a is attenuation with unit of nepers/㎝. From this study, it was confirmed that nondestructive ultrasonic method could be used in measuring average ferrite grain size indirectly.
하상경사가 변화는 실험실 데이터를 이용한 Chiu의 유속공식과 Manning 의 유속공식과의 비교분석
추태호(Choo, Tai-Ho),옥치율(Ok, Chi-Youl),이승관(Lee, Seoung-Kwan),제성진(Je, Sung-Jin) 한국산학기술학회 2007 한국산학기술학회 학술대회 Vol.- No.-
현재까지 수리학 분야에서 가장 많이 회자되고 인용된 공식이 있다면 아마도 1890년에 발표한 Manning의 유속 공식이라고 해도 과언은 아닐 것이다. 그만큼 그 쓰임새가 많았을 뿐만 아니라 사용의 편리성과 정확도에서도 매우 우수하였기 때문일 것이다. 그러나, 아무리 우수한 공식이라도 약점이 있듯이, Manning의 유속공식 역시 조도계수n을 추정하는데 많은 어려움이 있는 것도 주지의 사실이다. 이러한 어려움을 극복하기 위하여, 본 연구에서는 확률통계에서 사용되는 엔트로피 개념을 이용한 3차원 유속분포식인 Chiu의 유속공식을 사용하였다. 그러나 지금까지 실증적으로 Chiu의 유속공식과 Manning의 유속공식을 비교분석하였던 논문은 Chiu와 Choo의 논문에서 일부 언급된 것 외 논문에서는 찾아볼 수 없는 것이 현실이다. 따라서 본 연구에서는 하상경사를 임의로 변경 가능한 실험수로를 선택하여 정밀법에 의한 유속측정을 우선 실시하였다. 같은 지점의 같은 단면에서 하상경사(Ө)가 0.000935부터 0.025794까지 28번의 경사변화를 주고 각 경사마다 유량을 측정하여 28개의 유량측정 데이터를, Chiu의 유속공식과 Manning의 유속공식에 각각 적용하여, Chiu의 M과 Manning의 n사이의 관계뿐만 아니라, 하상경사변화에 따른 관련인자들을 함께 분석하였으며, 실측된 평균유속과도 함께 분석하였다.
Choo Yeon KIM(Choo Yeon KIM),Seunghyeon LEE(Seunghyeon LEE),Seong Soo CHA(Seong Soo CHA) 한국유통과학회 2024 The Journal of Industrial Distribution & Business( Vol.15 No.3
Purpose: This research aimed at understanding the dynamics of consumer behavior in the context of nostalgic desserts. The primary objective is to scrutinize how different attributes like quality, health, convenience, and trend influence customer satisfaction and their subsequent decision to repurchase nostalgic desserts. Research Method: The study leverages structural equation modeling, incorporating statistical tools such as SPSS and AMOS for a thorough analysis. It involves collecting data over a specified period, followed by correlation and trend analyses to deduce patterns and relationships. Results: The findings reveal that attributes such as quality, health, convenience, and trend significantly impact customer satisfaction and repurchase intentions. Interestingly, economic factors appeared to have a negligible effect on these decisions. The study offers a comprehensive understanding of the factors that influence consumer decisions in the context of nostalgic desserts, providing valuable implications for both academic research and practical marketing strategies. Conclusions: The insights garnered from this research are pivotal for formulating marketing strategies for nostalgic dessert brands. It underscores the importance of accentuating quality, health, and trend in product offerings to boost customer satisfaction and encourage repurchases. The study also sheds light on the evolving nature of consumer preferences and the integral role of nostalgia in shaping purchasing behaviors.