A multi-cylinder four cycle spark ignition engine equipped with on exhaust gas recirculation(EGR) system to reduce nitric oxide emission and to improve fuel consumption rate has been comprehensively simulated In a computer program including intake and exhaust manifolds. To achieve these goals, this program was tested against experiments performed on a standard production four cylinder four cycle gasoline engine with EGR system. As EGR rate Increased, the maximum temperature of combustion chamber and NO omission concentration decreased under each driving condition. But the emission concentration of CO didn't change much through whole district in spite of the increase of EGR rate. Fuel consumption rate improved under each driving condition according to the increased of EGR rate until 10 percent EGR rate. Therefore the degree of EGR depend not only on the NO emission but also on the economy and the engine performance criteria of the engine.

The combined effect of increased pressure/temperature and the reduced material thicknesses act to increase the stress on the radiator componets. The design life of the radiator is influenced by the cyclic stresses and corrosion, which act to weaken the materials, radiator mechanical failure occurs when a tube or solder Joint ruptures, causing coolant loss or insufficient heat rejection. Therefore, in this study, through strain measurement of the tubes in copper/brass radiator, the strain distribution of the tubes in radiator as function of temperature and pressure is obtained.

This paper presents a method of stress analysis of golf club. We define the sweet spot of golf club by the magnitude of torsional moment. Transfer matrix method was used for optimal design on sweet spot of golf club.

High temperature tensile tests, steady state creep tests, Internal stress tests and creep rupture tests using A17075 alloy( $T_{6}$ ) were performed over the temperature range of 9$0^{\circ}C$~50$0^{\circ}C$ (0.4 $T_{m}$ ~0.85 $T_{m}$ ) and stress range of 0.64~17.2(kgf/$\textrm{mm}^2$). The main results obtained in this paper were as follows. (1) The activation energies for yielding at the temperature of 0.4 $T_{m}$ ~0.75 $T_{m}$ were calculated to be 25.7~36.5kcal/mol, which were nearly equal to the activation energies for creep. (2) At around the temperature of 9$0^{\circ}C$~12$0^{\circ}C$ and under the stress level of 10~17.2(kgf/$\textrm{mm}^2$), and at around the temperature of 200~41$0^{\circ}C$ and under the stress level of 1.53~9.55(kgf/$\textrm{mm}^2$) and again at around the temperature of 470~50$0^{\circ}C$ and under the stress level of 0.62~l.02(kgf/$\textrm{mm}^2$), the applied stress dependence of steady state creep rate $n_{measu}$ measured were, respectively, 3.15, 6.62 and 1.1, which were in good agreement the calculated stress dependence $n_{ealeu}$ obtained by the difference of the applied stress dependence of the Internal stress and the ratio of the internal stress to the applied stress. (3) At the temperature range of 0.4~0.43 $T_{m}$ , and at the temperature range of 0.52~0.75 $T_{m}$ and again at the temperature range of 0.82~0.85 $T_{m}$ , the activation energies $Q_{measu}$ obtained by steady state creep rate, respective, 26. 16, 34.9, 36.2 and 36.1kcal/mol, which were in good agreement with those obtained with the activation energies under constant effective stress and the temperature dependence of Internal stress. (4) At the temperature range of the 0.52~0.73 $T_{m}$ and under the stress level of 1.53~9.55(kgf/$\textrm{mm}^2$), the stress dependence of rupture life(n’) measured was 6.3~6.6, which was in good agreement with the stress dependence of steady state creep rate(n). And at the same condition the activation energy for rupture( $Q_{f}$ ) measured was 32.0~36.9kca1/mol, which was also in good agreement with the activation energy obtained by steady state creep rate ( $Q_{c}$ ). (5) The rupture life( $t_{f}$ ) might be represented by athermal process attributed to the difference of the applied stress dependence of the internal stress and the ratio of the internal stress to the applied stress, and the thermal activated process attributied to the temperature dependence of the internal stress as $t_{f}$ = A'$\sigma$$_{a}$ ｛n(1-d $\sigma$$_{i}$ /d $\sigma$$_{a}$ )/(1-$\sigma$$_{i}$ / $\sigma$$_{a}$ )｝.exp[｛ $Q_{c}$ $^{*}$-( $n_{o}$ R $T^2$/ $E_{(T)}$) (d $E_{(T)}$/dT) - ( $n_{0}$ R $T^2$/ $\sigma$$_{a}$ - $\sigma$$_{i}$ ) (d $\sigma$$_{i}$ /dT)｝/RT]. (6) The relationship betwween Larson-Miller rupture parameter and logarithmic stress was linearly decreased, so creep rupture life of Al 7075 alloy seemed to be predicted exactly with Larson-Miller parameter.meter.

This Paper aims to examine the effect of shear lip formation from cross-sections on fatigue crack propagation rate in order to study the fatigue fracture behavior of the high strength aluminum material (Al 2024-T3). The following tests were achieved from this research. 1. As a result of depressing shear lip artificially by adding a side groove to a specimen, it is shown that the propagation rate of fatigue crack is faster than that of general specimen. 2. Through the two-step load test, the phenomenon that the shear lip decreases In the part of changed load gets observed. Consequently It Is shown that the crack propagation rate gets faster.

The growth of short cracks can be well described in terms of the effective stress intensity factor range, which is calculated on the base of crack closure. The relation between the crack opening SIF and crack length is determined from the experimental results. The crack opening SIF of short cracks, Kop, can be predicted from the crack opening SIF at threshold of long crack, Kop.L. The growth rate of short cracks at notch root can be predicted from the crack opening SIF of short cracks, Kop, and the growth equation of long cracks in region II.

The purpose of this study is to develop a CAD/CAM system for automatic creation and manufacturing of three dimension objects. The computer system used in this study made RAM 2M, CPU 80386, VGA graphic card. The results in this paper are as follows ; 1. By interconnect PC(personal computer) and NC(numerical control) milling machine with RS232C connector, we was constructed with CAD/CAM system. 2. The developed algorithm in this study is able to be design of three dimension object on the computer CRT and manufacturing of NC milling machine. 3. Because of design and modifying on the PC of objects, we can be saving time, cost and improvable precision of objects. 4. Essentially, we expect industrial accident to reduse according as we takes advantage of CAD/CAM system.

Until now, Industrial robotic sa(ety problems are not considered as a indust rial safety problems. In order to reduce industrial robotic safety problem, analyzing problem, risk control, and developing industrial robotic standard s are necessary. In this study, SAFEMIR(Safety Management for Industrial Robotic) is developed for preventing mul-function in industrial robotics. This system is consisted of Da ta Base Management System Module and Expert System Module which Is a part of Articial In telligence. Borland C++ and Foxpro 2.0 are used for implementing this system.

This study is conducted for both examination of a possiblity of danger and investigation of operational condition of selected 120 companies, to establish the safety standard of workplace hazards.

In recent years, mould industry in machining requires to increase machining productivity and to reduce costs, To adapt this trend it is necessary to optimize machine condition, Even though many researches in this area introduced various way to set the optimal condition, still there are not enough. Therefore this research was done to select the optimal cutting condition for industry, and to develop the computer program to select the optimal cutting condition automatically. The result of this research will contribute to increase machining productivity of various mould companies with the automatic selection of optimal cutting condition.

Manual lifting, as a part of Manual Materials Handling Activities, is recognized by authorities in the field of occupational health and safety as a major hazard to industrial workers. The most important problem in applying fuzzy model of manual materials lifting is the decision of membership functions on each approaches. : Biomechanical, Physiological, Psychophysical. The primary objectives of this paper suggests to process deciding the most acceptable membership functions for establishing permissible weights on manual lifting activities using fuzzy sets.

The main purpose of this study was to develop fuzzy models in order to decide system failure rate in industrial accident prevention. The purposed linguistic approach uses the Zadeh's concept of a linguistic variable with value which are not number. The problem of measurement Is the assignment of numbers to reprresnt properties of the involved events, object, or situation. Thus, in this study, part standard compatibility function was used.

In power transistor switching circuit have shunt snubber(dv/dt limiting capacitor) and series snubber (di/dt limiting inductor). The shunt snubber is used to reduce the turn-off switching loss and the series snubber is used to reduce the turn-on switching loss. Design procedures are derived for selecting the capacitance, inductor and resistance to limit the peak voltage and current values. The action of snubber is analyzed and applied to the design for safety PWM inverter.

The streaming current of insulating oil increases with increasing oil velocity and oil amount, A contact potential difference as an energetic state exits in the polymer thin film, both sides of which are contacted by two different metals having different work functions. Accordingly, the potential difference may be a cause for the short circuited transient current flowing through the external circuit. The polymers are electrificated as the electric field Is supplied, and the currents flow with increasing temperature.

Small rectangular explosion chamber of its size 25cmX25cmX32cm with a circular bursting diaphram at the top was used to study the mechanism of gas explosion to fire transition phenomena, the process of ignition of solid combustibles during a gas explosion. To visulize the explosion to fire transition phenomena, transparent acryl window and high speed camera system were used. The test piece of solid combustible in this experiments was a 5cm$\times$5cm square sheet of newspaper which was placed in the explosion chamber filled with a LPG-air mixture. The mixture was ignited by an electric spark at the center of the chamber. Explosion to fire transition phenomena and the behavior of out flow and in flow of gas through the opening yielded by bursting the diaphram was visualized with shlieren system and without shlieren system. Diameter of a bursting dlaphram at the top of the explosion chamber was varied 5cm, 10cm, and 15cm, and the position of test piece were varied with 6 point. Explosion pressure was measured with strain type pressure transducer, and the weight difference of the test piece before and after each experimental run was measured. By comparing the weight difference of solid combustibles before and after the experiment and the behavior of out flow and inflow of gas after explosion, it was found that the possibility of ignition was depends on the LPG-air mixture concentration and the exposure period of test piece to the burnt gas. Test result of this experiments it was found that the main factor of this phenomena are that heat transfer to the test piece, and the pyrolysis reaction of test piece. Based on the results, the mechanism of the explosion to fire transition phenomena were inferred ; gas explosion- heat transfer to solid combustibiles ; pyrolysis reaction of solid combutibles : air inflow ; mixing of the pyroly gas with air ignition.

The explosion characteristics of nonhomogeneous LPG-Air mixtures was measured in a cylindrical vessel and a pipe. The maximum explosion pressure, the maximum rate of explosion pressure rise, and the flame propagation velocity were measured and compared with that of homogeneous explosion by changing the effective factors on the explosion of nonhomogeneous mixtures such as pressure difference, effusion time and delay time. Explosion was occured even in the lower concentration than the lean flammability limit of mixture. The maximum explosion pressure was increased with increase of LPG concentration, however, the maximum explosion pressure rise was not in the nonhomogeneous explosion. An d the flame propagation velocity was decreased with nonhomogeneity, however, the maximum explosion pressure was always above 0.7kg/$\textrm{cm}^2$.

This work was carried out to investigate the effects of solid mass flow rate, mean particle diameter and mesh number of screen packing material on minimum carrying velocity, which defined as the superficial gas velocity of the upper limit of chocking phenomenon. Vertical pneumatic conveying was studied on a 4.6cm 1. D. pipe, 180cm in length. Experiments were performed in both the empty and the screen-packed pipe. It was also examined the effect of superficial gas velocity, solid mass flow, mean particle diameter, and mesh number of packing material on pressure drop. Minimum carrying velocity in screen packed-pipe was lower than that in an empty pipe. besides minimum carrying velocity was decreased with increase in mesh number of screen packing material. The pressure drop In vortical packed-pipe was Increased with superficial gas velocity, mean particle diameter, and mesh number of screen packing material.

Porphyrin-catalyzed reduction of TNT to triaminotoluene was performed in both batch reactions and a continuous process. Packed-bed reactors were used to study porphyrin-catalyzed reduction in a continuous process. A reactor was packed with DEAD(diethylaminoethyl)-substituted glass beads on which $Co^{+3}$_centered deuteroporpgyrin Ⅸ, -2, 4-disulfonic acid was immobilized, and another containing only DEAE glass beads was used as a control. The porphyrin exhibited catalytic activity in its immobilized state up to 100 hours of operation. Based on the successful abatement of nitrobodies by porphyrin-catalyzed reduction in both batch and continuous process, this process is recommended to be used as a pretreatment for biological treatment or carbon adsorption treatment of TNT wastes.

The stable and safe operation of a boiler system is essential for ensuring stability of the chemical processes. A dynamic simulation of a boiler drum was performed to identify the dynamics of the boiler drum. The obtained results represented that the variation of process variables disturb boiler system. So, disturbance rejection with tracking and constraints handing was necessary for stable operation of boiler drum. Among many controller, GPC has been known to show good performance in set point tracking than disturbance. In order to improve disturbance rejection performance measurable disturbance term was Introduced in basic GPC model. The controller which had tracking and disturbance rejection was designed for Improving the stable operation of a boiler system.

Thermosyphons are simple devices that can passively transport thermal energy over relatively long distance with little temperature degradation. These attributes permit the use of low grade thermal energy for thermal control of structures including the snow melting and deicing to the pavement surface. The thermosyphon system requires no costly energy input and Is completely maintenance free. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to transfer the geothermal energy to the pavement to obviate slipping traffic accidents due to freezing of pavement in winter.

우리나라는 지난 20여년간 산업화 지향정책을 통하여 비약적인 경제성장을 이룩하였음에도 불구하고 그 이면에는 너무나도 많은 희생이 치러졌음을 묵과할 수 없다. 이러한 희생 가운데 눈여겨보아야 할 부분으로 산업재해를 들지 않을 수 없다. 성장의 기치하에 능률만이 우선되는 상황하에서 인명은 극도로 경시되었고 이는 무수히 많은 산업재해를 양산하기에 이르렀다. 1991년도 1년 동안의 산업재해만을 보더라도 대상 근로자 7,922,704명중 1.6%에 달하는 128,169명이 산업재해로 인한 부상 및 사망재해를 당했다(노동부, 92 노동통계연감). 1992년에는 91년에 비하여 약간 감소한 추세를 보이고 있으나 산업재해자가 107,435명으로 여전히 산업재해자가 많음을 보여준다(서울신문, 93. 4. 6).

For the safety assessment of the demonstration-scale incineration plant for treating the combustible radioactive wastes, radiation doses of a worker and a residential individual were estimated. The demonstration plant showed a good performance of trial-burn tests using non-radioactive tracers with resulting In high mass reduction of around 40 times and very low emmission of dusts through a stack, which promised a high decontamination factor in an order of 10$^{7}$ . Based on the result s obtained from the trial-burns in the process, the estimation of radiation dose for workers and general publics near the plant was made using dose pathway calculation theories. The parametric values for calculation were selected from design and operational results of the process and from more conservative conditions In reference data. The estimated annual doses for workers and residential indivisuals were 3.07 $\times$ 10$^{-4}$ and 4.35 X 10$^{-8}$ $\mu$Sv/y, respectively, which were high enough to operate the process when comparing with the allowable dose limit in the regulation. The dose calculation models were quite applicable with showing an excellent safety for the process.

Volatilization of toxic heavy metals, especially, metal chlorides at elevated temperatures in oxidation conditions was observed using a thermogravimetric furnace since such metal chlorides used to be a cause for the disease of industrial workers by their toxicity and high volatile extent. Most of tested metal chloride compounds were evaporated or decomposed into gas phase at elevated temperatures ranged from 200~90$0^{\circ}C$, while CrCl$_3$ and NiC1$_2$became stable with converting into oxide forms. A kinetic model for evaporation/condensation could predict maximum evaporation flux and the calculated values were compared with real evaporation flux. The ratio of two fluxes could be explained as the fraction of impinging gas molecules to the condensing surface( $\alpha$ ) and obtained in the range of 10$^{-3}$ ~10$^{-9}$ for the experimented toxic heavy metal chlorides. This ratio might be used to define the volatile extent or toxicity of such toxic metal compounds. The schemes to avoid volatilization of toxic heavy metals Into the atmosphere were suggested as follows ; 1 ) controlling the compositions of metals and Chlorine produced substances( such as PVC ) in the treated materials using a reverse estimation from regulatory limit and characteristics of a processing facility, 2) Installation of wet type devices such as a scrubber for condensing the metal compounds.

Anthropometric characteristics and considerations of sex differences are essential for the correct design of ergonomic work spaces. This paper is concerned with longitudinal study on the physical growth in Korean youth. Three hundred eighty-seven subjects were selected from third year students of high schools, and their records on physical examination during the last twelve years were surveyed by longitudinal method. For boys and girls, this study investigated the anthropometric characteristics of physical structure and the shape of physical growth. The result showed that the physical growth spurt of girl occurred earlier than that of boy. Also, by regression analysis, the third-order polynomial function was suitable for the growth curves of stature and weight, and there were significant sex differences in the fitted curves.

Elimination of dangerous points is the most effective method for safety in mechanical equipments. The next effective method is recognized as isolation and/or safe-guarding of dangerous spots from human beings. With progress of mechanical automation technique such as industrial robots, the need for safe-guard-ins is now being enlarged. It is needless to say that when a machine-guard is designed and installed, a comprechensive understanding of human movement is indispensable. But in this country, there is no scientific for those thems, and no one verifield whether it is valid to apply general guideline such as OSHA's to Korean or not. Further, basic anthropometric items for safety reach standards are neither availble nor included in nation-wide anthropometry project. In this research, human anthropometry data of Korean youngsters are analyzed for safety barrier and safety slit width, and compared with guidelines of other countries-Germany, United Kingdom, Japan, and USA. Though they are standards for safety, since they are based upon their own peoples' data, some of them especially foot reach are not not applicable in this country. It should be notified that careful application of numeric value is very important.

Al합금 7075에 대해서 공작물 이송속도, 연삭깊이 및 유제 공급방법이 잔류응력에 미치는 영향을 실험적으로 행하였다. 가공 변질층에 형성된 잔류응력을 측정하기 위해 X선 회절법을 사용하였다. 개발된 노즐 공급방법 (Guide noazle)은 인장 잔류응력 및 연삭저항, 표면조도 부분에서 기존 노즐보다 좋은 효과를 가져 왔다. 연삭깊이 및 공작물 이송속도를 감속시키고 아울러 스파크 아웃을 행하면 잔류응력 및 표면 조도를 감소시킬 수 있다.

동적 문제에 대한 공간-시간 유한요소법을 제시하였다. 이 방법은 공간과 시간을 동일한 변수로 취급하였으며 공간-시간 영역에서의 유한요소 전개에 있어서는 연속적 갤러킨 방법에 근거하여 가중여분법을 이용하였다. 이 방법은 조건부 안정을 주는 고차원적 정확성을 주는 해법인 것이다.

상변화 에너지 저장장치는 변동하는 액체-고체 상접합면과 자연대류의 존재에 기인한 비선형성 때문에 해석적으로 분석하기가 어렵다. 핀(fin) 형태의 상변화 에너지 저장장치를 준선형화 시켜 열전달을 수치적으로 해석하여 실험 데이타와 비교 검증하였다. 대칭형 수평 핀에 대하여 준선형, 비정상의 얇은 2차원적 모델을 세우고 유한체적방법(FVM)에 의해 시간의 함수로 융해된 상변화물질의 비율과 액체-고체 상접합면의 형상을 예측하였다. 유한체적방법(FVM)에 의한 결과는 실험결과와 비교적 잘 일치하였다. 벽과 융해점 사이의 온도차가 클수록 융해된 상변화물질의 비율은 증가하였으며 대류항을 포함하는 경우가 없는 경우보다 실험결과에 더 가까운 해를 얻을 수 있었다.

본 논문은 하역작업이나 제품의 권상, 권하시 타워크레인의 로바스트 콘트롤을 고려한 타워크레인의 자동화에 관한 것이다. 본 논문을 위한 타워크레인의 모델방정식은 라그랑즈 방정식을 사용하였으며, 동방정식은 평행점 근방에서 선형화 하였다. 본 논문의 제어법으로서는 최적 레규레타법을 적용하였으며, 그 효용성은 설계된 최적 제어법을 위하여 16비트 마이크로컴퓨터를 이용하여 카고로우프의 진동제어와 그레인의 붐 및 트로리의 위치제어를 위한 실험결과로써 입증되었다.

각종 산업에 있어서 분체는 여러가지 형태로 다량 사용되고 있으며 분체 취급시 정전기에 의한 폭발, 화재 등 많은 재해가 발생되고 있다. 분진폭발은 과거에 탄광에서 탄진폭발에 의한 것이 대부분 이었지만 최근 플라스틱 공업, 유기합성 공업, 분말 공업 등 원재료와 제품을 분체로 취급하는 공정이 증가하면서 분진폭발 사고가 현저히 증가하였다. 그러나 현재 이러한 재해 방지를 위한 충분한 검토 및 대책이 잘 이루어지지 않고 있는 실정이다.

광석으로부터 생산된 금속의 양은 문명이 시작되고 부터 1750년대까지 전세계에서 약 2500만ton정도가 생산되었다고 추정되고 있다. 그러나 Fig. 1에서 보이는 것처럼 1980년대에는 그 생산량이 1년 간에 약 5억8천만ton이 되었고, 실제로 10년 간에 약 58억ton이 소비되기에 이르렀다. 그러나 금속자원은 무한히 있는 것이 아니고, 채굴기술에도 한계가 있기 때문에 머지않아 금속자원은 고갈해 버릴 것이다. 금속자원이 앞으로 어느 정도 기간까지 채굴이 가능할까 하는 것은 납이 22년, 아연이 41년, 구리가 53년, 철, 알루미늄이 230년 정도라고 추정되고 있다. 새로운 거대한 광맥이라도 발견된다면 이런 DATA는 다소 바뀔 수도 있겠으나, 앞으로 발전도상국들의 적극적인 경제활동으로 이러한 금속자원은 더욱 많이 사용될 것이며, 따라서 이와 같은 예상은 더욱 단축될 것이다.(중략)