• Proceedings of the Korean Society for Cognitive Science Conference
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• 2000.05a
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• pp.137-142
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• 2000

본 논문에서는 확률적 자연언어 처리에서 중요한 문제인 자료 희귀(data sparseness)의 어려움을 해결하는 새로운 방법으로 차원 축소 모델을 제시한다. 세 가지의 세부 방법이 제안되었으며 Katz의 back-off 방법의 성능을 최저로 했을 때에 비해 약 60%정도의 성능이 향상되었다. 현재까지 최고의 성능을 보이고 있는 유사도 기반의 방법에 비해서도 약 5∼20%의 성능이 향상되었다. 따라서 차원 축소 모델은 확률 추정의 새로운 방법으로 쓰일 수 있다.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.208-211
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• 2003

기존 IEEE 802.11 MAC (1)에서는 Fairness를 보장하며 Resource를 제공하는 것을 목표로 동일한 DIFS, Back-off 알고리즘, Source가 같은 경우 동일한 Frame size등을 사용하는 Specification을 작성하여 구현한다. 최근 Home Network과 같은 특수한 Ad-Hoc 환경에서의 이런 Fairness Resource Usage가 오히려 기대 성능을 떨어뜨리는 결과를 가져오고 있다. 이에 802.11 MAC에서 Backward Compatibility를 유지하면서 Prioritized DIFS/Backoff/Frame를 통해 차등화된 서비스를 제공하는 메커니즘을 제안하고자 하는 것이 본 논문의 목표이다.

• Journal of Korea Port Economic Association
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• v.19 no.1
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• pp.207-221
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• 2003

Now we are faced on the national policy to aim at the nationwide logistics center in North-East Asia. To come true, Korean ports developments policies are better off going towards integrated governmental supportive system build-up, activated infra-structures, back-yard developments, legal and institutional system, international co-ordination networks system, customer-oriented port management system like one-stop services, and multi-variate financing resources. Above all, Related governmental institutions strongly have self-confidences and devotional efforts to make them all implemented not losing own way.

• Proceedings of the Korea Port Economic Association Conference
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• 2003.07a
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• pp.343-357
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• 2003

Now we are faced on the national policy to aim at the nationwide logistics center in North-East Asia. To come true, Korean ports developments policies are better off going towards integrated governmental supportive system build-up, activated infra-structures, back-yard developments, legal and institutional system, international co-ordination networks system, customer-oriented port management system like one-stop services, and multi-variate financing resources. Above all, Related governmental institutions strongly have self-confidences and devotional efforts to make them all implemented not losing own way.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.475-489
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• 2010

In order to verify the enhancement of ozone and carbon monoxide (CO) during springtime in East Asia, we investigated weather conditions and data from remote sensors, air quality models, and air quality monitors. These include the geopotential height archived from the final (FNL) meteorological field, the potential vorticity and the wind velocity simulated by the Meteorological Mesoscale Model 5 (MM5), the back trajectory estimated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the total column amount of ozone and the aerosol index retrieved from the Total Ozone Mapping Spectrometer (TOMS), the total column density of CO retrieved from the Measurement of Pollution in the Troposphere (MOPITT), and the concentration of ozone and CO simulated by the Model for Ozone and Related Chemical Tracers (MOZART). In particular, the total column density of CO, which mightoriginate from the combustion of fossil fuels and the burning of biomass in China, increased in East Asia during spring 2000. In addition, the enhancement of total column amounts of ozone and CO appeared to be associated with both the upper cut-off low near 500 hPa and the frontogenesis of a surface cyclone during a weak Asian dust event. At the same time, high concentrations of ozone and CO on the Earth's surface were shown at the Seoul air quality monitoring site, located at the surface frontogenesis in Korea. It was clear that the ozone was invaded by the downward stretched vortex anomalies, which included the ozone-rich airflow, during movement and development of the cut-off low, and then there was the catalytic photochemical reaction of ozone precursors on the Earth's surface during the day. In addition, air pollutants such as CO and aerosol were tracked along both the cyclone vortex and the strong westerly as shown at the back trajectory in Seoul and Busan, respectively. Consequently, the maxima of ozone and CO between the two areas showed up differently because of the time lag between those gases, including their catalytic photochemical reactions together with the invasion from the upper troposphere, as well as the path of their transport from China during the weak Asian dust event.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.101-106
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• 2004

The process of removal of gummy proteinous material sericin from silk is commonly called as degumming loss or boil-off loss ratio. In the present study, the boil-off loss ratio in the cocoon shells of twelve multivoltine${\times}$bivoltine hybrids and their parents were analysed. Inheritance pattern of boil-off loss ratio was analysed in crosses involving high and low boil-off loss parents, F$_1$s, F$_2$s and back-crosses by parent off spring regression analysis. Heterosis and heterobeltiosis was also analysed for this character, Highly significant (P＞0.01) variations were observed in eight out of ten multivoltine and two out of five bivoltine parents indicating the presence of genetic variation in the expression of boil-off loss ratio. Among F$_1$ hybrids, ten hybrids expressed significant (P＞0.01) variations when compared with control hybrid PM${\times}$NB$_4$D$_2$. Significant negative heterosis was expressed in three multi ${\times}$ bi hybrids viz., BL67${\times}$CSR$_{101}$, 96A${\times}$CSR$_{19}$ and 96C${\times}$CSR$_{19}$, which is desirable for this character, whereas expression of heterobeltiosis was significant only with one hybrid, 96C${\times}$CSR$_{18}$ in desired direction. Studies on inheritance pattern showed that the character is heritable and contribution percentage of female and male in the ratio of 50.9: 49.1 and it appears that both the parents are influencing in the expression of boil-on loss ratio in silkworm. Based on the overall performance and evaluation by multiple trait evaluation index and also considering the expression of the boil-off loss ratio three hybrids vix., BL67 ${\times}$ CSR$_{101}$, 96A${\times}$CSR$_{19}$ and 96C${\times}$CSR$_{18}$ were found superior and recommended for commercial exploitation.n.ion.n.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.194-201
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• 2014

Age and growth of flathead grey mullet Mugil cephalus were estimated using samples collected by a two-side fyke net in the coastal water off Taean in 2008. Age was determined by examination of annuli in otoliths and total lengths at ages were back-calculated from otolth-body size relationship. Total length ranged from 239 to 605 mm and mainly between 400 and 550 mm. Observed ages ranged from 1 to 7 years old and mainly between 3 and 5 years old. Total length (L, mm) was linearly related to otolith radius (R, mm); L=15.3+87.9 R. Total lengths at the annulus formation in otolith were back-calculated by Frazer-Lee method. Estimated length at the age 1 was $316{\pm}40.6mm$ ($mean{\pm}SD$) showing a fast growth rate during the early growth stage. Total length at each age (t) showed a wide range indicating the big difference in growth rate among individuals. Growth in total length can be expressed by a Von Bertalanffy growth curve as $L_t=542[1-{\exp}\{-0.493 (t+0.769)\}]$.

• Journal of Internet Computing and Services
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• v.9 no.5
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• pp.153-163
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• 2008

Almost literature has so far proposed the modifications to IEEE 802.11 DCF MAC protocol to improve system throughput and average delay. Jitter(variance in packet delays) is, however, considered as an important QoS parameter for real-time streaming service which is popularized increasingly. Unfortunately, legacy access protocol for WLAN can't support the jitter. This paper proposes two schemes modifying the DCF MAC protocol to reduce the average value of jitter for multimedia frames arrived at received nodes. The one scheme, referred to as DCW-DCF(Decreasing Contention Window-DCF), reduces CW(Contention Window) size by half whenever a transmitted frame collided against other frames and back-off happens. Also, it increase initial CW size according as the link utilization and the collision probability increase. The other scheme, referred to as D-DIFS(Differential-DIFS), assigns different values to DIFS. That is, the DIFS interval is deceased as the number of back-off for a frame increases. In this paper, the two schemes are evaluated through simulation using ns2 and simulation results show that the proposed schemes are effective for improving the jitter property of standard WLAN.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.344-347
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• 2011

Unlike a terrestrial wireless sensor network which uses radio waves, UWASN(Underwater Acoustic Sensor Network) relies on acoustic waves. There are lots of ongoing researches for long latency and limited bandwidth of underwater sensor network by using acoustic wave. Packets transferred by node often colide in underwater sensor network due to long latency. To solve this kind of problem, in general, Back-off scheme which is used in wireless network is used. However, fixed Slot-time according to node allocation generates useless time delay, and this lowers network performance. In this thesis, active setting technique of Slot-time is proposed, and applied for already studied MAC protocol. At the conclusion, it was proved that the MAC protocol using the proposed scheme has better performance than existing MAC protocol as a result comparison.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.91-96
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• 2006

High efficiency switching mode circuits such as class I amplifiers have been well known in the MHz frequency range. The class E amplifier is a type of switching mode amplifier offering very high efficiency approaching 100%. In this paper, the class E amplifier has been designed by using the harmonic balance method of circuit simulator. The designed amplifier is realized by using pHEMT and microstrip line, shows 66% power added efficiency (PAE) at 2.4GHz with 17.6dBm output power. With -3dBm input power of wireless LAN, measured output spec01m can meet the required IEEE 802.11g standard spectrum mask. That means the required amplifier back off of 9dB from $P_{ldB}$ to satisfy the required wireless LAN spectrum mask.