• The Transactions of the Korea Information Processing Society
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• v.6 no.11
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• pp.3116-3123
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• 1999

Current disk systems are generally designed to reduce read traffic more effectively. Hence, write traffic of the I/O workload could potentially become a bottleneck of the disk system performance. In order to overcome this problem without much cost, this paper presents using outermost-zone track of multi-zoned recording disk as a secondary disk cache. The proposed disk cache improves the disk system performance by following exploitations: speed difference between block transfer and track transfer, difference in transfer rate between outermost-zone tracks and inner tracks, reduction in the seek time caused by decreasing the number of disk cache tracks, and idle period during burst accesses. In addition, it does not waste the disk space because it allocates the caching space by the cylinder unit. The simulation results show that the proposed system improves 2.54∼3.11 times better in terms of average response time for write operations than existing disk systems..

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.194-198
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• 2004

The thermo-hydro-mechanical (T-H-M) process is one of major issues in the performance assessment of a high level waste (HLW) repository. An engineering-scale test was planned and its experimental set-up has being installed, to validate the T-H-M behavior in the buffer of a reference disposal system. The experimental set-up consists of 4 major components: the confining cylinder with its hydration water tank, the bentonite block, the heating system, and the sensors and instruments. The monitoring and data acquisition system is employed to control the heater to maintain the temperature of $95^{\circ}C$ at the interface of the heater and bentonite blocks and to collect signals from sensors and instruments installed in the bentonite blocks.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1060-1065
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• 2007

This paper summarizes a design procedure of radiated noise from engine blocks of marine engines. This air-borne noise is one of the significant noise contributors including the aeroacoustic noise due to intake and exhaust and the re-radiation due to structure-borne noise. Excitation forces by engine operations are evaluated taking into account the power generation mechanism from the burning process to the subsequence motion of internal parts; piston, connecting rod, and crank shaft. The acoustic transfer vector method is incorporated to effectively simulate the radiated noise field under the various operation conditions. A contribution analysis for the various excitations to the radiated noise is conducted. It is found that the firing pressure is the main source of the radiated noise, and so the structure of the cylinder can be modified to significantly reduce the radiated noise from the engine block.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.19-27
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• 2010

Cylinder block is driven by tapered piston for bent-axis type piston pump, so that geometrical mechanism is very complicate. Piston rod must have not separated from shaft when shaft and piston rod is assembled. For this reason, shaft design is changed. Finite element analysis is performed for analyzed structural stability and flexible dynamic behavior. The result of the analysis, maximum equivalent stress occurred under yield stress, therefore structural stability is satisfactory. and flexible dynamic analysis give useful information about driving gear. These background data is avail of manufacture of piston pump.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.875-880
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• 2002

It is necessary to determine the vibration source and its transmission paths in order to develop a low-noise compressor. Through the use of multiple-input/single-output(MISO) mode1, the transmission paths of vibration within a reciprocating compressor have been investigated. In order to identify the transmission path, we measure the accelerations of the block and transverse vibrations of the line discharge tube. As outputs, vibrations of compressor shell were measured at three positions; cylinder head, one near the suction line, and the top of upper shell. The partial coherence function and transfer function are obtained ken the measured data, and the results are observed in order to determine vibration source and its influence on the shell vibration.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.205-212
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• 1998

In this study, the effects of water vapor in inlet air on combustion efficiency, general performance, knock characteristics and emission gas concentration were investig- ated through the experiments of combustion and vibration analyses, emission gas analysis by changing water vapor quantity in inlet air with temperature and humidity auto control unit. With partial vapor pressure increase, the brake torque at wide open throttle status decreased and the average ignition delay angle increased, IMEP (indicated mean effective pressured using the integral and 3rd derivatives of filtered cylinder pressure as knock intensity, which matched well with the method of frequency power spectrum of block vibration signal. Water vapor in intake air had influence on the spark knock sensitivity. With the increase of water vapor content in intake air NOx emission was decreased and HC emission was increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.41-49
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• 1993

Piston slap is one of the major sources of noise in a 4-cycle diesel engine. Piston slap is not only one of major source mounted near the top and bottom of the piston thrust and antithrust skirts. Effects of engine speed, load and coolant temperature on piston motion were investigated. The measured piston motion showed 6 slapes per cycle resulting from the change of side force. Major piston slap timing was retarded as engine speeds became higher. The increase of engine load made large piston transverse movement toward thrust side of cylinder block. Piston transverse movement was due to reduced piston-liner clearance at higher coolant temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.486-489
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• 2003

To reduce lateral force of traditional plunger type piston in the swash plate type hydraulic piston pumps and motors, we have proposed rod type piston with ball joint on both ends. We have studied the theoretical reaction force on two types of piston moving in the cylinder block bore. and made an experiment for the resistance force measurement on a reciprocating motion of plunger and rod type piston, changing the test condition such as swash plate angel and supply oil pressure and so on. As a result. a rod type piston has more smaller resistance force, about 29%. than a plunger type one.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.142-142
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• 2017

High Flory-Huggins interaction parameter (${\chi}$)를 가지는 polystyrene-block-dimethylsiloxane (PS-b-PDMS)는 초미세 패턴 제작과 우수한 defect density, 우수한 edge roughness 특성으로 향상된 패턴을 제공한다는 점에서 반도체 분야에서 많은 연구가 되고 있다. 하지만, PS와 PDMS 사이에 존재하는 큰 surface tension의 차이로 인해 PDMS는 PS와 air 사이에서 segregate되기 때문에 수직배향에 불리하여 high aspect ratio (HAR)을 가지는 cylinder, lamellar 패턴 제작에 있어 큰 어려움을 가진다. 본 연구에서는 이러한 문제를 해결하기 위해, PS-b-PDMS BCP 패턴과 하부 실리콘 기판 사이에 amorphous carbon layer (ACL)를 삽입하여 효과적으로 pattern transfer하는 공정을 연구하였다. 플라즈마를 이용하여 무한대에 가까운 etch selectivity를 가지는 식각 공정을 개발함으로써 낮은 aspect ratio를 가지는 PS-b-PDMS BCP 패턴의 한계점을 극복하였다. Large-x value를 가지는 BCPs를 이용하여도 매우 높은 aspect ratio를 가지면서 동시에 pattern quality를 향상시킬 수 있는 plasma process를 제시하였다.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.490-495
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• 1998

In this paper an asymmetric hydraulic actuator which consists of single acting cylinder and servo valve is modeled for a quarter car active suspension system. This model regards the force as an internal state rather than a control input. The control input of the model is the sum of oil flows that pass through the valve's orifices. The resulting dynamic equation in the state space ap-pears a feedback connection of a nominal linear time in-variant term with a nonlinear bounded uncertain block. Since this model makes it possible to eliminate the force control phase, analysis and controller design are made straightforward and simple. Well known LQR method is then applied. Simulation and test rig experiment show the effectiveness of this approach in modeling and control.