전기유동유체의 전기적 내구성에 대한 실험적 고찰

박우철,이현창,이형식 三陟大學校 2001 論文集 Vol.34 No.1

This paper presents experimental results on material properties of an electro-rheological(ER) fluids subjected to electrical fatigues. As a first step, two types of ER fluids made of arabic gum and methy1 cellulose(MC) choosing 25% of particle weight-concentration. Following the construction of test mechanism for electrical durability of ER fluid, the dynamic yield shear stress and current density of the ER fluids are experimentally distilled as a function of electric field. The yield shear stress of operated ER fluids are distilled and compared with those of unused ER fluids. In addition, the surface roughness of the employed electrode are evaluated as a function of the number of the electric-field cycle.

알루미나 세라믹스의 분위기 압력변화에 따른 마모특성에 관한 연구

박홍식,김용완,김형자,김영대 釜慶大學校 1996 釜慶大學校 論文集 Vol.1 No.2

This study was investigated to the tribology characteristics for the alumina ceramics(Al₂O₃) in the variation of ambient pressure. The sliding wear test was carried out under the condition of the various applied load, sliding distance and the ambient pressure with mate specimen made of STB2 stee. The results obtained are as follows : 1. As the ambient pressure decreases, the friction coefficient increases, becasue the protective layer made of absorption substance can not be fromed due to decrease of the amount of ambient gas. 2. The friction coefficient of purity 85% alumina is higher than that of purity 95% and 99.7% alumina because of the influence of heat accumulation. 3. As the applied load increases in each ambient pressure, the friction coefficient increases due to brittle fraction of alumina grain and great action of cohesion. However, the gap of the friction coefficient by the variation of the contact load is small in the vacuum. 4. The friction coefficient regarding the variation of sliding distance increases by on inital 60 meters of the sliding distance, however, the friction coefficient is almost constant after the sliding distance.

石炭, 洋灰關聯産業이 嶺東地域經濟에 미치는 波及效果 分析

박형래,강영갑,양정식,류한천 강릉대학교동해안지역연구소 1994 東海岸硏究 Vol.5 No.1

본 논문의 목적은 지역산업연관표를 이용하여 영동지역의 산업연관 관계를 계량적으로 분석하는데 있다. 이러한 산업연관 분석방법은 영동지역의 산업상호간 경제활동과 구조적 특징을 체계적으로 분석하고 장래의 산업 변화에 대한 예측을 가능하게 한다. 본연구의 결과에 나타난 몇가지 중요한 점은 다음과 같다. 첫째, 석탄, 양회산업은 지역산업연관효과가 매우 높은 수준으로 측정됨으로써 이들 특화산업이 지역발전의 선도산업으로서 중요한 역할을 수행하고 있음을 보여주고 있다. 둘째, 이들 두 산업이 영동지역내에서는 중요한 산업이지만 양회산업의 경우 지역전체 생산에서 차지하는 비중이 매우 높은 산업임에도 불구하고 고용승수로 측정되는 고용효과 측면에서는 그 영향이 그리 크지 않은 것으로 나타났다. 이것은 시멘트 산업이 자본집약적인 장치산업으로서 자본의 규모에 비해 고용자를 많이 사용하지 않기 때문인 것으로 평가된다. The purpose of this study is to analyze the quantitative characteristics of the Young-Dong regional economy in industrial interleatedness by using the 1990 I-O table. The analysis of this structural character and industrial interrelatedness makes it possible to estimate the current structural problems and future prospects of Young-Dong regional economy. The findings of this study can be summarized as follows: 1)The coal mining and cement industries sector have relatively high and wide-spreading positive impacts on the regional output and income. 2)Above two sectors showed different impacts pattern on the employment. Coal mining sector gives relatively higher impacts on the regional employment but cement industry sector gives lower impacts on the regional economy because cement industries sector is labor saving industries with large equipment requirement.

DTFC에 의한 對稱形 패� 스위칭 컴퓨터망의 POWER特性

박형식,양회국 경북대학교 공과대학 1981 工大硏究誌 Vol.10 No.-

The Performance of DTFC(Drop and Throttle Flow Control), a kind of IBL(Input Buffer Limit) scheme, is observed with respect to several values of threshold L, which controls to accept input packets and transit packets into the input buffer of a node, in the symmetrical packet-switched network. Performance measures are throughput, delay, and power of a tradeoff between throughput and delay. Computer results show that there exist a suboptimal threshold L with respect to throughput, but not with respect to power.

熱間 알미늄 押出型材의 型材係數에 관한 연구

박정수,이형식 연세대학교 산업기술연구소 1975 논문집 Vol.6 No.1

In the hot extrusion of aluminum alloys for architectural uses, a wide variety of extrusion shapes are encountered under various requirements necessitating it different operational conditions to adopt. However, the prevailing cost estimate for the extrusion shapes practised so far among the extruders in this country has been a unique cost per kilogram without regard to the geometric configuration and its operational condition, which has presented itself as one of the most unreasonable aspect in the plant operation and for the estimation of their prices. In this study, a shape factor that indicates the degree of relative complexity in the extrusion process for every extrusion shape reflecting its geometric configuration and operational condition was established, and the relationship between the shape factor and the productivity was observed through the practical operation. It was found that a logarithmic relationship was existing between the shape factor and the extrusion output per hour, where the output being decreased with the increase of the shape factor. And also, empirical equations were established for obtaining the extrusion output per hour with the variable of the shape factor. Meanwhile, the extrusion recovery, the life span of die and the fuel and power consumption in the extrusion were analyzed, which, together with the extrusion time, were used in establishing a formula for an overall cost estimate for every extrusion shape. There were marked differences in the overall costs of aluminum shapes, and the costs were dependent on the shape factor, type of die and the applicable dimensional tolerances. Among them, the shape factor was found to be the most dominant agent in the cost estimate. Comparing with the conventional method of unique cost estimation, the formulas for calculation of the overall costs for every shape which were newly established in this study provide the most reasonable basis for the pricing of extruded aluminum shapes, thereby making it possible to benefit both the manufacturers and the consumers.

前腕部 經穴 取穴에서 骨度分寸法과 一夫法의 比較 硏究

박히준,채윤병,차웅석,박종배,이혜정,이향숙,인창식,고형균,김수영,최일환,김강식,문정배,배기태,유경환,육근영,정병주,손인철,임사비나 WHO COLLABORATING CENTRE FOR TRADITIONAL MEDICINE 2004 東西醫學硏究所 論文集 Vol.2004 No.-

Background : The cun measurement System, an essential and convenient method in locating acupoints, has been widely used in the practice of acupuncture. However, traditional cun measurement has been criticized for its lack of reliability. Objectives : The purposes of this study are to determine if one cun measured by the directional methods have a consistency with that of proportional methods and to investigate which factors are related with these differences, especially in forearm. Methods : The distance between the elbow crease and the wrist crease of forearm was compared to a reference value of one cun obtained by the directional method. In this method, one cun is one third of the distance between index finger and Small finger of a subject, measured at proximal interphalangeal joint. In addition, to investigate the factors influencing the differences between these two methods, we measured the height and body weight and calculated body mass index (BMI). Finally we analyzed the factors correlated with these lengths by linear regression test. Results : The results showed that one cun obtained by the directional methods were significantly different from one cun by the proportional methods in forearm. It was demonstrated that the length acquired with the directional method was more correlated with body weight and body mass index, while the length obtained by the proportional method was more correlated with the height.

非線形 理論에 依한 채터 解析

이형식,정준기,박태형 연세대학교 산업기술연구소 1983 논문집 Vol.15 No.2

The chatter analysis has been studied by many authors using non-linear. In this study, the stability chart obtained from experimental work with a lathe was qualitatively compared with the result of chatter analysis by non-linear theory. Experimental results verify that the stability of the machining process is affected by the width of cut in the following manner. As the chip width is increased from zero with the rotational speed of the workpiece kept constant, three ranges are distinguished; (a) unconditionally stable range, (b) conditionally stable range, (c) unstable range. In the conditionally stable range the system is stable for small disturbances but unstable when these exceed a certain level. When the chatter occurs, the amplitude initially increases and stabilizes itself at a finite level. This phenomenon agrees well with the analysis of non-linear theory qualitatively.

總輸膽管 結紮術후 Hepatic Glycogen 變化에 관한 形態學的 硏究

李亨周,李永浩,朴景蘭,金源式 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.1

For the study on the changes of hepatic glycogen after common bile duct ligation, Sprague -Dawley rats (b.w. 250± 20gm, male) were used as experimental animal. In expermental group, at 3hrs, 6hrs, 9hrs, 12hrs, 24hrs, 48hrs, 72hrs, 96hrs, and 120hrs after ligation, the common bile duct at the point of about 1cm proximal portion from its duodenal opening, the liver specimens were collected under ether anesthesia. Simple laparotomy was performed in control rats. After fixation, the specimens were sectioned 5㎛ thickness and stained with Periodic Acid Schiff, and observed under light microscope. Also, transmission electron microscopic photos were obtained with H-7000(Hitachi Co.) TEM. The results were as followings: 1. PAS reactions were changed into negative 6hours after common bile duct ligation. 2. Glycogen depletion after common bile duct ligation was closely related with functional lobule, but not in simple laparotomized rats. 3. In the common bile duct ligated rats, PAS negativity continued in the zone I until 120hours after ligation.

랫드에서 인체 재조합 적혈구 조혈인자, rHuEPO의 13주 정맥투여 아만성독성에 관한 연구

김형식,곽승준,천선아,박현선,한하수,임소영,안미영,김원배,김병문,안병옥,홍성렬,이병무 성균관대학교 약학연구소 1998 成均藥硏論文集 Vol.10 No.1

A recombinant human erythropoietin (rHuEPO) was administered intravenously at dosage levels of 0, 100, 500, and 2500 IU/㎏/day for a period of 13 weeks. There were no observed clinical signs and deaths related to treatment in all groups tested. Decreases in body weight gain and food consumption were observed only in males of 2,500 IU/㎏ group after 2 weeks. In hematological parameters, erythrocyte content, hematocrit values and hemoglobin concentration were dose-dependently increased in rHuEPO treated groups. The ratio between kidney weight and whole body weight was significantly increased in females of 500 and 2,500 IU/㎏ groups. The spleen weight was also increased in both sexes of 500 and 2,500 IU/㎏ groups. However, the absolute weight change of other organs was not observed. In histopathological examinations, the renal tubular basophilia was observed only in males and females of 2,500 IU/㎏ groups. From these results, it is concluded that the no-observed adverse effect level(NOAEL) of rHuEPO is 100 IU/㎏ in rats in the present study.

입상활성탄에 의한 방향족, 지방족고리 아민류 및 아미노산의 액상흡착

이성식,김형준,유명호,박성은 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.1

Equilibrium studies for the adsorption of aromatic, alipatic cyclic amines and amino acid from aqueous solutions onto granular activated carbon have been carried out at 298K. Two and Three-parameter isotherms were tested. Among the equations tried, the two-parameter equations of Freundlich equation yield a better fit, The Langmuir equation, However gives the poorest overall fit. For three-parameter isotherm equation, the Redlich-Peterson equation gives the most satisfactory fit over the entire range of concentrations. The adsorption amounts of the aromatic amines onto GAC increase with the number of methyl group in pyridine ring.