• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.317-323
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• 2006

The conventional Wheeler cap method can extract the reliable efficiency of the antenna when the antenna operates as a simple series or parallel RLC circuit model. This method, however, may give an unreliable efficiency when the antenna under test has a complicated operating principle. In this paper, we revisit the conventional Wheeler cap method and propose a modified Wheeler cap method basedon the high-order circuit model. The proposed method can provide an accurate efficiency even for the antenna with a more complicated operating principle. Then we calculate efficiencies of other antennas with different operating principles and compare the results with the simulations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.10
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• pp.45-51
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• 2003

In this paper, a scan-based low power BIST (Built-In Self-Test) architecture is proposed. The proposed architecture is based on STUMPS, which uses a LFSR (Linear Feedback Shift Register) as the test generator, a MISR(Multiple Input Shift Register) as the reponse compactor, and SRL(Shift Register Latch) channels as multiple scan paths. In the proposed BIST a degenerate MISR structure is used for every SRL channel; this offers reduced area overheads and has less impact on performance than the STUMPS techniques. The proposed BIST is designed to support both test-per-clock and test-per-scan techniques, and in test-per-scan the total power consumption of the circuit can be reduced dramatically by suppressing the effects of scan data on the circuits. Results of the experiments on ISCAS 89 benchmark circuits show that this architecture is also suitable for detecting path delay faults, when the hamming distance of the data in the SRL channel is considered.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1499-1506
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• 2011

The IHX (intermediate heat exchanger) is a key component of nuclear hydrogen systems for the production of massive amounts hydrogen. The IHX transfers the $950^{\circ}C$ heat generated by the VHTR (very high temperature reactor) to a hydrogen production plant. The Korea Atomic Energy Research Institute established a small-scale gas loop to test the performance of key VHTR components and manufactured a small-scale PCHE (printed circuit heat exchanger) prototype, which is being considered as a candidate for the IHX, for testing in the small-scale gas loop. In this study, as a part of the high-temperature structural integrity evaluation of the small-scale PCHE prototype, we carried out high-temperature structural analysis modeling and macroscopic thermal and structural analysis for the small-scale PCHE prototype under the small-scale gas loop test conditions. This analysis serves as a precedent study to scheduled PCHE performance test in the small-scale gas loop. The results obtained in this study will be compared with the test results for the small-scale PCHE and then used to design the medium-scale PCHE prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.11-17
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• 2003

In this paper, we implemented 2-wire (data gnd) RS232C serial communication interface by applying the Collision Sensing Multiple Access(CSMA) Protocol. The transmitting and receiving wires of RS232C pert are connected together by the interface circuit forming data wire without hardware modification On two-wired common channel connection simultaneous transmission Don mere than two hosts causes data collision. The collision is detected by loop-back test of transmission data comparing with the fed back data to detect the data distortion. Various models are adopted to reduce the probability of retransmitted data collision and experiments show the performance of each cases. Due to allowing multiple hosts to be accessed through the common communication channel with minimum circuit addition the result of this paper can be easily applied for conventional RS232C instruments and machines to connect to the single data communication line.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.111-118
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• 2018

In order to develop a local stiffness-variant stretchable substrate with the soft PDMS/hard PDMS/FPCB configuration consisting of two stiffness-different polydimethylsiloxane (PDMS) parts and flexible printed circuit board, a FPCB was bonded to PDMS using the acrylic-silicone double-sided tape and the interfacial adhesion of the PDMS/FPCB was evaluated. The pull strength of the FPCB, which was bonded to the fully cured PDMS using the silicone adhesive of the double-sided tape, was 259 kPa and the delamination during the pull test occurred at the interface between the PDMS and the silicone adhesive. On the contrary, the bonding process, for which the FPCB was bonded using the silicone adhesive to the PDMS partially cured for 15~20 minutes at $60^{\circ}C$ and then the PDMS was fully cured for 12 hours at $60^{\circ}C$, exhibited the remarkably enhanced pull strength of 1,007~1,094 kPa. With the above mentioned bonding process, the delamination during the pull test was observed at the interface between the FPCB and the acrylic adhesive of the acrylic-silicone double sided tape.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.245-251
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• 2015

In an electrical reliability test of a printed circuit board (PCB), the impact of the micro probing pins on the PCB needs to be checked to ascertain the quality of the circuit. In this study, the impact of the dynamic movement of the probing pin on the pad was observed. As a misaligned pin can exert horizontal force on the pad of the PCB, this study focused on the behavior of a misaligned probing pin. The parameters of observation were the circular and flat edges of the probing pin. The effects of the speed of movement, diameter, and the length of projection of the probing pin were also investigated. The results demonstrated that slippage angle is strongly affected by the shape of the edge of the probing pin, and that projection length is an important factor affecting pin slippage. In contrast, the speed of movement of the probing pin was able to double the slippage angle.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.2
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• pp.23-27
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• 2024

In this study, the time-dependent warpage behavior caused by the viscoelastic properties of prepreg in a printed circuit board (PCB) was analyzed by finite element method (FEM). The accurate viscoelastic properties of the prepreg were measured by stress relaxation test, which were then incorporated into constructed warpage analysis model. When the PCB was subjected to repeated thermal cycles, the warpage of the PCB was restored to its initial state when only the elastic properties of the prepreg were considered, but when the viscoelastic properties were also considered, the warpage was not restored and permanent warpage change occurred. The warpage analysis for three different types of prepreg was conducted to compare their mechanical reliability, and the results showed that materials with elastic properties dominating over viscoelastic properties experienced less warpage, resulting in better mechanical reliability.

• Journal of the Korean Magnetics Society
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• v.26 no.5
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• pp.154-158
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• 2016

A CRDM (Control Rod Drive Mechanism) is an electromagnetic device which drives a control rod assembly linearly to regulate the reactivity of a nuclear core. An RPIS (Rod Position Indication System) is used as a position indicator for a control rod assembly of a CRDM of SMART, and an RPIS consists of permanent magnets and reed switches. SMART is designed for the maximum coolant temperature of $350^{\circ}C$, and the permanent magnets are installed inside of the reactor. The reed switches and electrical circuit are installed outside of the reactor on the other hand. Test coil for a reed switch is test equipment for quality verification of a reed switch, and a test coil consists of a coil and core. In this study, magnetic property of test coil and permanent magnet on a reed switch is compared by using finite element electromagnetic simulation.

• Journal of the Semiconductor & Display Technology
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• v.8 no.4
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• pp.53-58
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• 2009

A SMT mounter is a kind of equipment that mounts SMD parts quickly on the printed circuit board. By using linear motors, it is controlled with high speed and precision, which is similar to semi-conductor and display process equipment. It is necessarily used in an assembly process of an electronic device. Mobile devices such as a mobile phone and PDA are required to reduce mount areas due to the demands for high performance and small size. Hence, super small sized and complex mobile devices have been developed. To improve the productivity of the corresponding equipment, designs with large sized, high speed, and multidisciplinary functions have been consistently performed. Meanwhile, a design trend of large size and light-weight on SMT mounter causes a low natural frequency of systems and vibration problems at the high speed operation. In this paper, the dynamic characteristics of the SMD mounter system were investigated through a modal test and transmissibility test, and verified by finite element method. Also, various design improvement was performed to avoid the resonance phenomena.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1593-1598
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• 1994

Recently rotary-arc, thermal expansion and their composite interrupters are widely used in the distribution power system because they have lots of advantages in making the larger interrupting capacity, the smaller size, the lighter weight and the less surge. A model interrupter of rotary-arc type, which has constant stroke and thermal expansion volume, was studied by varying the design parameters, i.e. the number of turns of the driving coil, the inner diameter of the moving contact, the gas pressure and the shape of the fixed contact for this project. Short cicuit current interrupting tests were conducted to the model interrupters by varying the requirements from 42% to 175% of the test voltage, interrupting current and transient recovery voltage for the test duty No.4 of 7.2kV 12.5kA single phase test. The pressure rise, minimum and maximum arcing times were analyzed for each model interrupter. All types of model interrupters showed good interrupting performances and sufficient design margins for the ratings.