• 한국지열·수열에너지학회논문집
• /
• 제14권4호
• /
• pp.43-52
• /
• 2018

This paper presents the cooling performance analysis results of a ground-source heat pump (GSHP) system using hybrid ground heat exchanger (HGHE). In this paper, the HGHE refers to the ground heat exchanger (GHE) using both a vertical GHE and a surface water heat exchanger (SWHE). In order to evaluate the system performance, we installed monitoring sensors for measuring temperatures and power consumption, and then measured operation data with 4 different load burdened ratios of the hybrid GHE, Mode 1~Mode 4. The measurement results show that the system with HGHE mainly operates in Mode 1 and Mode 2 over the entire measurement period. The average cooling coefficient of performance (COP) for heat pump unit was 5.18, while the system was 2.79. In steady state, the heat pump COP was slightly decreased with an increase of entering source temperature. In addition, the parallel use of SWHE and VGHE was beneficial to the system performance; however, further research are needed to optimize the design data for various load ratios of the HGHE.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2002년도 추계학술대회 논문집(II)
• /
• pp.898-903
• /
• 2002

The railroad is a means of large transportation which has many talents such as a safety and a regularity. That is a results from various confidential performance tests and evaluations of the system. The railroad system consist of various subsystems - vehicle, power supply, signal, communications, track structures, operations, etc. Among them, as an item of safety evaluation there is a measurement of wheel/rail force, so called a measurement of derailment coefficient. This is a very important item because a derailment of a train will bring about a big accident. Especially it is more inportant in high speed rail of which operation speed is over two times as fast as existing rail. In this paper, it is introduced to preprocess the wheelset for measuring wheel/rail force of high speed rail, such as to treat a measuring wheelset, its finite element analysis, adhesion of strain gauges and static load test.

• 한국전기전자재료학회논문지
• /
• 제30권4호
• /
• pp.253-257
• /
• 2017

Nowadays, it is increasingly important to detect whether cables are live for the operator's safety if there is a sudden power failure. It is especially hard to detect the electrical field of an underground line because of shielding. This paper on detection of live-line states in cables studied the detection characteristics of the change in the magnetic field and axis as the frequency, voltage, and distance at the same load are changed using 3 axes. A search coil type was used as a magnetic field sensor with non-contact. We found that magnetic fields decrease proportionally to the square of the distance and the decrease of rated voltage with load effected to magnetic field. The magnetic field was detected by 3-axis sensors given correct proximity, but appeared as noise components beyond a distance of 2 cm.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 춘계학술대회 논문집
• /
• pp.762-767
• /
• 2003

The railroad is a means of large transportation which has many talents such as a safety and a regularity. That is a results from various confidential performance tests and evalutions of the system. The railroad system consist of various subsystems - vehicle, power spply, signal communications, track structures, operations, etc. Among them as an item of safety evaluation there is a measurement of wheel/rail force, so called a measurement of derailment coefficient. This is a very important item because a derailment of a train will bring about a big accident. Especially it is more important in high speed rail of which operation speed is over two times as fast as existing rail. In this paper, it is introduced to preprocess the wheelset for measuring wheel/rail force of Gwangiu EMU, such as to treat a measuring wheelset its finite element analysis, adhesion of strain gauges and static load test.

• 한국정밀공학회지
• /
• 제18권6호
• /
• pp.133-140
• /
• 2001

This paper suggests another system for a cutting force measuring tool in a milling process. Generally, tool dynamometer is taken into account for the most appropriate cutting force measuring tool in the analysis of cutting mechanism. However, high price and limited space make it difficult to be in-situ system for controllable milling process. Although an alternative method using AC current of servo-motor has been suggested, it is unsuitable for cutting force control because of small upper frequency limit and noise. The cutting force measuring system is composed of two load cells placed between the moving table bracket and the nut flange part of ballscrew. It has many advantages such as low cost and wide range measurement than tool dynamometer because of the built-in moving table and the low cost load cell. The static and dynamic model of the measuring system using imbeded load cell is introduced. Various Experiments are carried out to validate both models. By comparing the cutting forces from a series of end milling experiments on the tool dynamometer and the system developed in this paper, the accuracy of the cutting force measuring system is verified. Upper frequency limit is measured by the experiment of dynamic characteristics.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 가을 학술발표회 논문집
• /
• pp.277-284
• /
• 2000

Using the large diameter (D ＝ 2,500mm, L ＝ 40m) batter steel pipe piles, designed as compression piles but used as reaction piles during the static compression load test of socketed test piles (D ＝ 1,000mm, L ＝ 40m), static pile load tests for large diameter instrumented rock-socketed piles were performed. The reaction steel pipe piles were driven 20m into the marine deposit and weathered rock layer and then l0m socketed with reinforced concrete through the weathered rock layer and into hard rock layer. Steel pipe and concrete in the steel pile part, and concrete and rebars in the socketed parts were instrumented to measure strains in each part. The pullout amounts of reaction pile heads were also measured with LVDT. During the static pile load test, total compressional load of about 20MN was loaded on the head of test piles, but load above 20MN was not loaded due to lack of loading capacity of loading system. Over the course of the study, maximum pullout amount up to 7mm was measured in the heads of reaction piles when loaded op to 10MN and 1mm of pullout amount was measured. More than 85% of pullout load was transfered in the residual weathered rock layer and about 10% in the soft rock layer, which was somewhat different transfer mechanism in the static compressional load tests.

• 대한전기학회논문지:전력기술부문A
• /
• 제52권3호
• /
• pp.179-182
• /
• 2003

Component-based method for load model not only should include the performances of the load components, but also should take into consideration the core losses of transformers, the line losses and the capacitor banks. Especially, capacitor bank affects the accuracy of reactive load model in load modeling. But it is difficult to identify actual reactive powers of capacitor banks in power system for load modeling. This research improves the component-based modeling method including uncertain capacitor bank. The proposed method is hybrid technique, which adds the measurement-based method to the existing component-based method for reliable information of capacitor band. The results of case studies were presented to verify the validity of the proposed method.

• 산업경영시스템학회지
• /
• 제16권27호
• /
• pp.43-49
• /
• 1993

The purpose of this study is to develope a computer-generated work measurement system for creating and maintaining standard data as well as labor standards applying MODAPTS(Modular Arrangement of Predetermined Time Standards) technique. The system consists of three major parts. The first part is a work measurement program applying MODAPTS technique for work standards. The second part is a work scheduling program which calculate each operator's machine and job allocations, operation and load schedules, wage and wage incentives and direct labor costs etc. The last part is the case study application program for R-Instrument Manufacturing Industry. The whole system is programmed by dbase-Ⅲ and by pop-up mu for IBM PC compatibles.

• 감성과학
• /
• 제4권1호
• /
• pp.1-5
• /
• 2001

The evaluation of mental workload is measured by subjective ratings, physiological signals. It takes long time to analysis the measured signals and is very tedious and time-consumming work. Therefore, to evaluate the affect of workload effectively, real-time measurement system is required. In this paper, real-time mental workload measurement system using cardiac autonomic indiced which reflect well the mental workload was developed and evaluated. Analyzed indices were HR, IBI, Lorentz plot, CSI, CVI, and LF/HF ratio of heart rate variability. The system was applied to evaluate the affect of arithmetic task and showed good results. This system was consisted of ECG amplifier, A/D converter, and personal computer, and algorithm was implemented using LabVIEW.

• 소성∙가공
• /
• 제11권7호
• /
• pp.620-627
• /
• 2002

The purpose of this paper is the development of an automated measurement system for micro spring based on the digital image processing technique. This micro spring can be used in various engineering applications such as filament, load bearing springs, hard disk suspension and many others. Main functionality of the micro spring inspection system is to measure the representative pitch of the micro spring. The derivative operators are used for edge detection in gray level image. Measurement system developed in this paper consisted of new auto feeding mechanism to take advantage of air pressure. In the process of development of the micro spring inspection system based on the image processing and analysis, strong background technology and know-how have been accumulated to measure micro mechanical parts.