• Environmental and Resource Economics Review
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• v.14 no.2
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• pp.291-336
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• 2005

This paper investigates how oil price changes have an impact on the Korean manufacturing production activities. For this investigation, we use a structural VAR motel to estimate impulse response functions of industrial production, producer price and export price to an oil price increase over manufacturing industries. It finds that in most manufacturing industries, an oil price increase leads to decreases in industrial productions and domestic prices except energy intensive industries, but to increases in industrial export prices except non-metallic (26), computers and offic machinery (30), electronic components, radio, television and communication (32) industries. This result explains that an oil price increase makes negative impacts on the manufacturing production activities not only through demand slowdown in the domestic markets but also through supply contraction in the export markets.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.70-79
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• 2024

Raman analyzer is an analytical technique that utilizes the "Raman effect", which occurs when light is scattered by the inherent vibrations of molecules. It is used for molecular identification and composition analysis. In the natural gas industry, it is widely used in bunkering and tank lorry fields in addition to LNG export and import terminals. In this study, a LNG-specific Raman analyzer was installed and operated under actual field conditions to analyze the composition and principal properties (calorific value, reference density, etc.) of LNG. The measured LNG composition and calorific value were compared with those obtained by conventional gas chromatograph that are currently in operation and validated. The test results showed that the Raman analyzer provided rapid and stable measurements of LNG composition and calorific value. When comparing the calorific value, which serves as the basis for LNG transactions, with the results from conventional gas chromatograph, the Raman analyzer met the acceptable error criteria. Furthermore, the measurement results obtained in this study satisfied the accuracy criteria of relevant international standards (ASTM D7940-14) and demonstrated similar outcomes compared to large-scale international demonstration cases.

• Environmental and Resource Economics Review
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• v.18 no.4
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• pp.653-693
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• 2009

Using the Korean environmental input output analysis, this paper provides the emission intensities of the chemicals, especially, the toxic and carcinogenic substances, by linking the structure of demand, and the policy mix to abate these substances emissions. Acording to the results, Industries with the highest total emission intensities(TEI) of toxic substances are ranked : Printing and reproduction of recorded media(21), Other transportation equipment(26), Pulp and paper(11), Leather and fur products(9), Fiber yarn and fabrics(7). And the highest TEI of carcinogenic substances are Wood and wooden products(10), Motor vehicles and parts(25), Plastic and rubber products(15), Audio, video and communications equipment(23), etc.. The economic factors of changing these emissions are emission intensities and final demands. The effective combinations of policy instruments to abate these emissions are varied by the industries and substances. For example, Government need to execute the effective TEI management in the Fiber yarn and fabrics(7) sector, and, in furniture(27) sector, the reduction of final demand is more effective.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1211-1214
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• 1992

AC servo motor drives, Fara DS series, proposed in this paper can be effectively used in robots, CNC machine tools, and FA system with AC servo motors as actuators. The inverter of the AC servo drive consists of IGBT (Insulated Gate Bipolar Transistor) which have high switching frequency. Noises and vibrations generated in variable speed control of AC servo motors can be greatly reduced due to their high switching frequencies. In the developed servo drive, maximum torque is always generated in the whole speed range by compensating phase shift, which results from the nonlinearies of the AC servo motor during abrupt acceleration and deceleration. Abundant protection functions are provided to prevent abnormal state of the servo motor, and furthermore diverse user options are considered provided for the effective application. The proposed AC servo motor drive is designed to minimize velocity variation with respect to external load, supply voltage, environmental temperature, and humidity, so can be widely used in the fields of factory automation including robots and CNC msachine tools.

• The Magazine of the IEIE
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• v.28 no.7
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• pp.49-55
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• 2001

1970년대에 개발된 마이크로 프로세서는 제어기기 분야 및 소형 컴퓨터에서 주로 사용되어 오다가 1980년대에 이르러 RISC(Reduced Instruction Set Computer) 구조의 도입으로 중대형 컴퓨터에 이르기까지 광범위하게 사용되고 있다. 또한 반도체 기술의 급격한 발전으로 슈퍼스칼라 구조가 마이크로 프로세서에서도 적용되고 있으며 동작 속도도 수백 MHz에 이르고 있다. 마이크로 프로세서는 프로그램을 수행하기 위해서 프로그램과 데이터를 메모리로부터 읽어 와야 한다. 그런데 메모리 용량은 빠른 속도로 증가하고 있지만 동작 속도는 마이크로 프로세서의 동작 속도에 크게 미치지 못하고 있다. 1980년에 DRAM의 접근 속도는 250nsec이었으나 1998년에 RDRAM의 동작속도는 300MHz로 70여배 빨라졌다. 그러나 마이크로프로세서는 1980년에 8086의 동작 속도가 8MHz이던 것이 1998년에는 팬티엄-2가 500MHz에 이르고 있다. 더욱이 팬티엄-2는 슈퍼스칼라 구조이므로 이를 감안하면 1GHz 이상에 이르러 120여 배 빨라진 것을 알 수 있다. 이와 같은 메모리 속도와 마이크로 프로세서 속도 차이에 더하여, 메모리와 마이크로 프로세서를 인쇄 회로 기판에서 연결하는데 따른 물리적 특성은 변화하지 않으므로 데이터 전송 폭을 넓히는 것에는 한계가 있다. 따라서 향후 컴퓨터 성능 발달을 제한하는 주요 요소 중 하나는 마이크로 프로세서와 메모리 사이의 데이터 전송 폭이다. 프로그램과 데이터가 메모리에 저장되는 본 뉴먼 방식의 컴퓨터에서 데이터 전송 폭을 줄이기 위해서는 코드 밀도(Code Density)가 높은 컴퓨터 구조를 연구하는 것이 필요하다. 한편 마이크로 프로세서는 실장 제어용으로 거의 모든 전자 제품 및 자동화 기기에서 채용하고 있다. 특히 냉장고, 에어콘, 전축, TV, 세탁기 등 가전기기와 Fax, 복사기, 프린터 등 사무용기기와 자동차, 선박, 자동화기계 등 사무 및 산업용 기기와 PDA(휴대용 정보 기기), NC(Network Computer) 등 정보 기기 그리고 각종 오락기, 노래 반주지 등 정보 기기 등에서 사용하는 실장 제어용 마이크로 프로세서 시장은 매년 10% 이상씩 성장하고 있으며, 21세기 산업을 주도하는 핵심 기술로 자리 매김하고 있다. 이러한 실장 제어용 기기는 마이크로 프로세서와 메모리 및 입출력 자이가 하나의 반도체에 집적되는 경우가 많다. 그런데 반도체 가격은 반도체 크기에 따라 결정되며, 가장 넓은 면적을 차지하는 것은 메모리이다. 따라서 반도체 가격을 낮추기 위해서는 메모리 크기를 줄여야 하며, 이를 위해서 또한 코드 밀도가 높은 컴퓨터 구조에 대한 연구가 필요하다. 최근에는 322비트 RISC 명령어를 16비트 명령어로 축약한 구조가 연구되었다. ARM-7TDMI는 ARM-7의 16비트 축약 명령어 구조이며, TR4101은 MIPS-R3000의 16비트 축약 명령어 구조이다. 이들 16비트 축약 명령어 RISC는 종래 RISC와의 호환성을 위하여 2가지 모드로 동작하므로 구조가 복잡하고, 16비트 명령어에서는 8개의 레지스타만을 접근할 수 있으므로 성능이 크게 떨어지는 단점을 가진다.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.2
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• pp.33-40
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• 2019

Many companies have tried to develop wind power generators with a larger capacity, smaller size and lighter weight. High temperature superconducting (HTS) generators are more suitable for wind power systems because they can reduce volume and weight compared with conventional generators. However, the HTS generator has problems such as huge vacuum vessel and the difficulty of repairing the HTS field coils. These problems can be overcome through the modularization of the HTS field coil. The HTS module coil require a current leads (CLs) for deliver DC current, which causes a large heat transfer load. Therefore, CLs should be designed optimally for reducing the conduction and Joule heat loads. This paper deals with a structural design and thermal analysis of a module coil for a 750 kW-class HTS generator. The conduction and radiation heat loads of the module coils were analysed using a 3D finite element method program. As a result, the total thermal load was less than the cooling capacity of the cryo-cooler. The design results can be effectively utilized to develop a superconducting generator for wind power generation systems.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.74-82
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• 2007

The M-Method that measures the speed of actuator with counting the number of Reaction wheel Tacho Pulse has the many advantages such that a realization is simple and measuring time is uniform, but it also has the disadvantage that measuring speed becomes worse as the wheel speed goes lower. On the contrary, the T-Method that measures the time duration between the pulses is more accurate at lower-speed and its time delay is smaller than M-Method, but its realization is more difficult than M-Method because measuring time is varying with wheel speed variation. Thought M/T Method mixing M-Method with T-Method is widely used in order to measure the speed in the motor industrial area, one of two methods has been used in the spacecraft design area. Therefore, we try to apply both methods together to measuring the speed of Reaction Wheel, the core actuator for low earth orbit satellite. This paper provides the Reaction Wheel simulation board located in the Spacecraft Dynamic Simulator, ground support test set.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.5
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• pp.356-362
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• 1999

Based on the assumption that film density increases exponentially with exposure in the industrial radiographic film. an equation representing the characteristic curves of industrial radiographic films and a new density-thickness relation are suggested. The accuracy and reliability of the suggested relation has been tested using radiographs of a carbon steel step wedge with known thickness variation by polychromatic X-ray and ${\gamma}$-ray ($Ir^{192}$). The experimental results were well agreed to the proposed relation in the range of film densities from 1.0 to 3.5 and it was more accurate than the conventional relation. It is also found that ${\gamma}$-ray is more effective in this purpose than polychromatic X-ray, which results in variation of effective linear absorption coefficient due to beam hardening effect as thickness increases. Therefore using the equation and experimentally determined parameters the quantitative evaluation of thickness variation is possible and it can be used to evaluate the depth of local corrosion of pressure vessels in plants.

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.42-50
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• 2021

Along with the rapid growth of the food service industry, food safety requirements and hygiene are increasing in importance in restaurants and hotels. Accordingly, there is a need for quick and practical monitoring techniques to determine hygiene status in the field. In this study, we investigated 5 domestic 5-star hotels specifically, personal hygiene (hands of workers), cooking utensils (knife, cutting board, food storage container, slicing machine blade, ice-maker scoop) and other facilities (refrigerator handle, sink). In addition, we examined the hygiene management status of customer contact points (tongs for buffet, etc.) to derive the correlation between the ATP values as a, a verification method. As a result of our five-hotel survey, we found that cooking utensils and personal hygiene were relatively sanitary compared to other inspection items (cookware 92.2%, personal hygiene 91.4%, facilities and equipment 76.19%, customer contact items 88.6%). According to our ATP-based mothod, kitchen utensils (51 ± 45 RLU/25㎠) were relatively clean compared to other with facilities and equipment (167 ± 123 RLU/25㎠). In the present study, we also evaluated the usefulness of the ATP bioluminescence method for monitoring surface hygiene at hotel restaurants. After correlation analysis of surveillance of hygienic status points and ATP assay, most results showed negative and high correlation (-0.64--0.89). Our ATP assay (92 ± 67 RLU/25㎠) of each item after cleaning showed signigicantly reduced results compared to the ATP assay (1020 ± 1254 RLU/25㎠) for normal status, thereby indicating its suitability as a tool to verify the validity of cleaning. By our results, ATP bioluminescence could be used as an effective tool for visual numerical evaluation of invisible contaminants.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.71-82
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• 2006

One of the most popular pre-reinforcement methods of tunnel heading in cohesionless soils would be the fore-polling of grouted pipes, known as RPUM (reinforced protective umbrella method) or UAM (umbrella arch method). This technique allows safe excavation even in poor ground conditions by creating longitudinal arch parallel to the tunnel axis as the tunnel advances. Some previous studies on the reinforcing effects have been performed using numerical methods and/or laboratory-based small scale model tests. The complexity of boundary conditions imposes difficulties in representing the tunnelling procedure in laboratory tests and theoretical approaches. Full-scale study to identify reinforcing effects of the tunnel heading has rarely been carried out so far. In this study, a large scale model testing for a tunnel in granular soils was performed. Reinforcing patterns considered are four cases, Non-Reinforced, Crown-Reinforced, Crown & Face-Reinforced, and Face-Reinforced. The behavior of ground and pipes as reinforcing member were fully measured as the surcharge pressure applied. The influences of reinforcing pattern, pipe length, and face reinforcement were investigated in terms of stress and displacement. It is revealed that only the Face-Reinforced has decreased sufficiently both vertical settlement in tunnel heading and horizontal displacement on the face. Vertical stresses along the tunnel axis were concentrated in tunnel heading from the test results, so the heading should be reinforced before tunnel advancing. Most of maximum axial forces and bending moments for Crown-reinforced were measured at 0.75D from the face. Also it should be recommended that the minimum length of the pipe is more than l.0D for crown reinforcement.