• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.6 no.4
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• pp.255-261
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• 1977

This study was concerned with the performance of solar air heater using parallel channels. Heat transmission model was developed and fabricated to increase the economic feasibility for solar heating system by using the cheap zinc plate. The prformance was discussed as a function of mass flow rate, and plate, inlet and outlet temperatures. Experimental results show that heat transmission model is sufficient for the analysis of thermal characteristics of air heater and collection efficiency is better than the domestic water heater, as the range 32-49 percent. Collection efficiency in the 2 layers of glass cover is better than that in 1 layer, so it is considered better to use the 2 layers of glass cover during the cold winter season in Korea.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.287-290
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• 1999

In the transmitter of optical fiber transmission systems, a time-division multiplexer combines several parallel data streams into a single data stream with a high bit rate. In this paper, we design a 2:1 (2-channels) time-division multiplexer using SiGe HBT with emitter size of 2$\times$8${\mu}{\textrm}{m}$$^2$. The operation speed is 10Gbps, the rise and fall times of 20-80% are 34ps and 35ps, respectively and the dissipation of power is 0.86W.

• Publications of The Korean Astronomical Society
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• v.11 no.1
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• pp.231-242
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• 1996

We made 250 kHz filter bank based on FBS250 model designed by Millitech. It consists of 256 channels centered at 1391 MHz. The minimum detectable input level is -56 dBm/channel, and the maximum continuous integration time is about 1.3 seconds. This spectrometer can be operated in parallel or series mode with other spectrometers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.10
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• pp.885-891
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• 2010

Thermal management is important for enhancing the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs) and is taken into account in the design of PEMFCs. In general, cooling pates with circulating liquid coolant (water) are inserted between several unit cells to exhaust the reaction heat from PEMFCs. In this study, computational fluid dynamics (CFD) simulations were performed to characterize the uniform cooling performance of parallel multipass serpentine flow fields (MPSFFs) that were used as coolant flow channels in PEMFCs. The cooling performances of conventional serpentine and parallel flow fields were also evaluated for the purpose of comparison. The CFD results showed that the use of parallel MPSFFs can help reduce the temperature nonuniformity, and thus, can favorably enhance the performance and durability of PEMFCs.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2544-2552
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• 1997

This paper presents three multiprocess models for parallel protocol implementation, that is, (1)channel communication model, (2)fork-join model, and (3)event polling model. For the specification of parallelism for each model, a parallel programming language, Par. C System, is used. to measure the performance of multiprocess models, we implemented the Internet Protocol Suite(IPS) Internet Protocol (IP) for each model by writing the parallel language on the Transputer. After decomposing the IP functions into two parts, that is, the sending side and the receiving side, the parallelism in both sides is exploited in the form of Multiple Instruction Single Data (MISD). Three models are evaluated and compared on the basis of various run-time overheads, such as an event sending via channels in the parallel channel communication model, process creating in the fork-join model and context switching in the event polling model, at the sending side and the receiving side. The event polling model has lower processing delays as about 77% and 9% in comparison with the channel communication model and the fork-join model at the sending side, respectively. At the receiving side, the fork-join model has lower processing delays as about 55% and 107% in comparison with the channel communication model and the event polling model, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.6
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• pp.78-85
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• 2009

In time-varying multipath fading channels, orthogonal frequency division multiple access (OFDMA) uplink systems suffer severe performance degradation caused by inter-channel interference (ICI). In this paper, we propose a hybrid interference cancellation (HIC) for suppressing the degradation effect of ICI. The proposed HIC can achieve both exact interference cancellation and low detection complexity through efficient combination of parallel detection and serial cancellation. Simulation results show that, as the effect of Doppler increases, the proposed HIC achieves bit error rate (BER) performance enhancement in compared with severe performance degradation of conventional OFDMA receivers. In addition, both the computational complexity and total detection time are reduced.

• The KIPS Transactions:PartA
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• v.15A no.2
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• pp.87-94
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• 2008

Message races should be detected for debugging effectively message-passing programs because they can cause non-deterministic executions of a program. Previous tools for detecting message races report that message races occur in every receive operation which is expected to receive any messages. However message races might not occur in the receive operation if each of messages is transmitted through a different logical communication channel so that their incorrect detection makes it a difficult task for programmers to debug programs. In this paper we suggest a tool, MPIRace-Check, which can exactly detect message races by checking the concurrency between send/receive operations, and by inspecting the logical communication channels of the messages. To detect message races, this tool uses the vector timestamp to check if send and receive operations are concurrent during an execution of a program and it also uses the message envelop to inspect if the logical communication channels of transmitted messages are the same. In our experiment, we show that our tool can exactly detect message races with efficiency using MPI_RTED and a benchmark program. By detecting message races exactly, therefore, our tool enables programmers to develop reliable parallel programs reducing the burden of debugging.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.87-92
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• 2005

This paper analyzes the performance for an improved multistage parallel interference cancellation (PIC) technique with a reverse-link synchronous transmission technique (RLSTT) for DS-CDMA system in a frequency-selective Rayleigh fading channel with an imperfect power control scheme. The performance degradation due to power control error (PCE), which is approximated by a log-normally distributed random variable, is estimated as a function of the standard deviation of the PCE. The uncoded bit error performance is evaluated in order to estimate the system capacity. Comparing with the conventional one-stage PIC system, we show achievable gain around $60\%$ by the RLSTT even in the presence of PCE. We conclude that the capacity can be further improved via RLSTT, which alleviates the detrimental effects of the PCE

• Progress in Medical Physics
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• v.8 no.1
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• pp.3-15
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• 1997

Adrenal chromaffin cells secrete catecholamine in response to acetylcholine. The secretory response has absolute requirement for extracellular calcium, indication that $Ca^{2+}$ influx through voltage dependent $Ca^{2+}$ channel (VDCC) is the primary trigger of the secretion cascade. Although the existence of various types of $Ca^{2+}$ channels has been explored using patch clamp technique in adrenal chromaffin cells, the contribution of different types of $Ca^{2+}$ channels to catecholamine secretion remains to be established. To investigate the quantative contribution of different types of $Ca^{2+}$ channels to cate-cholamine secretion, $Ca^{2+}$ current($I_{Ca}$) and the resultant membrane capacitance increment($\Delta{C}_{m}$) were simultaneoulsy measured. Software based phasor detector technique was used to monitor $\Delta{C}_{m}$. After blockade of L type VDCC with nicardipine (1$\mu$M), $I_{ca}$ was blocked to 43.85$\pm$6.72%(mean$\pm$SEM) of control and the resultant ㅿC$_{m}$ was reduced ot 30.10$\pm$16.44% of control. In the presence of nicardipine and $\omega$-conotoxin in GVIA(l$\mu$M), an N type VDCC antagonist, $I_{ca}$ was blocked to 11.62$\pm$2.96% of control and the resultant $\Delta{C}_{m}$ was reduced to 26.13$\pm$8.25% of control. Finally, in the presence of L, N, and P type $Ca^{2\pm}$ channel antagonists(nicardipine, $\omega$-Conotoxin GVIA, and $\omega$-agatoxin IVA, respectively), $I_{ca}$ and resultant $\Delta{C}_{m}$ were almost completely blocked. From the observation of parallel effects of $Ca^{2+}$ channel antagonists on $I_{ca}$ and $\Delta{C}_{m}$, it was concluded that L, N, and also P type $Ca^{2+}$ channels served and $Ca^{2+}$ source for exocytosis and no difference was observed in their efficiency to evoke exocytosis amost L, N, and P type $Ca^{2+}$ channels.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.4
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• pp.195-200
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• 2015

The thermal performance in the channels with two-wall rectangular convergent/divergent cross-sectional areas along the axial distance was investigated experimentally. The ribbed rectangular convergent/divergent channels were manufactured with a fixed rib height (e) = 10 mm and the ratio of rib spacing (p) to height (e) = 10. Three different parallel angled ribs (a = $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$) were each placed on the channel's one sided wall only. The convergent channel of $D_{ho}/D_{hi}=0.67$ and the divergent channel of $D_{ho}/D_{hi}=1.49$ were considered. The ribbed divergent channel produced better thermal performance than the ribbed convergent channel in three different restrictions; identical flow rate, identical pumping power, and identical pressure loss.