• KOREAN JOURNAL OF CROP SCIENCE
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• v.4 no.1
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• pp.31-71
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• 1968

To clarify the breeding behavior of the hybrids between tropical and temperate area rice varieties, investigations were made on heading days and grain sterility. In this study, crosses were made in half way diallel involving 7 varieties: 2 photoperied sensitive Indicas, 2 less sensitive intermediate Indicas, 1 Ponlai Japonica and 2 high temperature sensitive Japonicas. The parents and $F_1$s were grown under 10 hours and 14 hours daylength controlled conditions at both IRRI(International Rice Research Institute, N$14^{\circ}$17') and Suwon(N$37^{\circ}$16'). F2s with their parents were grown at IRRI in the short day season, and at Suwon under natural conditions. Fa lines with their parents were grown at Suwon under natural conditions. Observations were made for heading days and sterility. The results are summarized as follow; 1. Heading days : 1. For the $F_1$s, earliness showed dominance or overdominance to lateness under the 10 hours condition, and dominance or partial dominance under the 14 hours conditions, at both IRRI and Suwon. 2. For the $F_2$s grown at IRRI during the shortday season earliness appeared to be dominant over lateness and segregation was not distinct and continuous. In the early season culture of $F_2$s at Suwon earliness showed partial dominance or was intermediate. In the proper season culture of $F_2$s lateness showed partial dominance or was intermediate. 3. In the combinations between late parental varieties which do not head at Suwon, transgressive segregants bearing effective panicles were obtained. 4. The crosses of parental varieties having long basic vegetative growth duration showed bigger variance in heading days, and significant correlation was found between of parental varieties and the mean coefficient of variance for parental arrays. 5. The means of heading days of F2 populations were significantly correlated with those of $F_1$ or mid-parents. The means of F 8 lines were also highly correlated with the means of $F_2$s, but, the means of $F_3$ lines grown at Suwon and of their parental $F_2$ individual, grown at IRRI were not correlated. 6. A faint heritability was calculated from the regression of $F_3$ lines grown at Suwon on the $F_2$ individuals grown at IRRI for most combinations, especially in the combinations involving shortday sensitive varieties. This implies low efficiency for the selection of heading days of $F_2$ individuals at IRRI to be grown in lines at Suwon. 7. No significant reciprocal effects were measured for $F_1$ and $F_2$ mean heading days. 8. Partitioning the observed photoperiod sensitivity. into two components, parental array mean md the deviation from this array mean, the parental photoperiod sensitivity contributing to the hybrids was measured in terms of general and specific combining ability for photoperiod sensitivity. 9. The photoperiod sensitivity of $F_1$s was higher than that of the parents, and it decreased as the generation progressed in most combinations of tested varieties. 10. The response of heading days to difference of temperature was weaker for $F_1$ hybrids than for the parents. The differences of temperature responses between the longday and shortday treatments were specific for the variety. 2. Sterility : 1. The $F_1$ sterility was specific for the combinations and not correlated to the parental sterility. The sterility of $F_1$s grown under the 10 hours condition was higher than of those grown under 14 hours. These results were the same at both locations, IRRI and Suwon. 2. The high sterile combinations in $F_1$ showed high sterility in $F_2$. The combinations between a high photoperiod sensitive variety and a high temperature sensitive variety showed high sterility and wider variance. 3. The mean sterility of $F_2$s was lower than of $F_1$s and the mean of $F_3$ lines was lower than of $F_2$s. Sterility decreased as the generation progressed, and the differences of $F_3$ sterility of different combinations were not significant. 4. A faint correlation between grain sterility and pollen sterility was observed in $F_2$ populations. 5. No significant reciprocal effects were measured in $F_1$ and $F_2$ sterility. 6. Following Griffing's method, specific combining ability effects were higher than general combining ability effects, especially in the combinations between highly photoperiod sensitive varieties and highly temperature sensitive varieties. 7. No distinct correlations were found between $F_2$ individual sterility grown at IRRI and $F_3$ line sterility grown at Suwon. 8. No distinct correlations were observed between heading days and sterility of $F_2$ individuals.

• Journal of the Korean Society for Railway
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• v.17 no.3
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• pp.157-164
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• 2014

The contact force between the pantograph and the catenary is a key factor determining the current collection quality, as they can ensure stable electrical power to the train. In this study, we analyzed the dynamic contact force for HEMU-430X depending on the train speed. It was confirmed through the results that the standard deviation of the contact force increases with an increase in the train speed. It was also verified that the span of the catenary system is a very important factor with regard to the contact force when analyzed with frequency analysis. To secure stable power in speed that exceeds 400km/h, the statistical variation of the contact force should be minimized. To realize this, the catenary tension was increased and the mass of the pan-head was decreased. The ensuing effects were then quantitatively analyzed in terms of the contact force. In addition, the differences in the contact force between a tunnel and an open field were analyzed based on a frequency analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.291-292
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• 2012

MOSFET 구조에서 metal oxide에 기반을 둔 게이트 유전체의 연구는 실리콘(Si)을 기반으로 한 반도체 발명이래로 가장 인상적인 발전을 이뤄 왔다. 이는 metal oxide의 높은 유전상수 특성이 $SiO_2$보다 우수하고, 유전체 박막의 두께 감소로 인한 전기적 특성 저하를 보완하기 때문이다. 특히 지난 10년 동안, Hafnium에 기반을 둔 $HfO_2$는 차세대 반도체용 유전 물질로 전기적 구조적 특성에 대한 연구가 활발히 진행되어왔다. 그러나 현재까지 $HfO_2$에 대한 nano-mechanical 특성 연구는 미미하여 이에 대한 연구가 필요하다. 이에 본 연구에서는 Hf 및 $HfO_2$ 박막의 증착 및 열처리 조건을 다르게 하여 실험을 진행하였다. 시료는 rf magnetron sputter를 이용하여 Si 기판위에 Hafnium target으로 산소유량(4, 6 sccm)을 달리하여 증착하였고, 이후 furnace에서 400에서 $800^{\circ}C$까지 질소분위기에서 20분간 열처리를 실시하였다. 실험결과 산소 유량을 6 sccm으로 증착한 시료의 current density 성능이 모든 열처리 과정에서 증가하였다. Nano-indenter로 측정하고 Weibull distribution으로 정량적 계산을 한 경도 (Hardness)는 as-deposited 시료를 기준으로 $400^{\circ}C$에서는 감소했으나 온도가 높아질수록 증가하였다. 특히, $400^{\circ}C$ 열처리한 시료에서 산소농도에(4 sccm : 5.35 GPa, 6 sccm : 6.15 GPa)따른 두 시료간의 변화가 가장 두드러졌다. 반면에, 탄성계수 (Elastic modulus)는 산소농도 6 sccm을 넣고 증착된 시료들이 4 sccm을 넣고 증착한 시료보다 모두 높은 값을 나타냈다. 또한, $800^{\circ}C$ 열처리한 시료에서 산소농도에(4 sccm : 128.88 GPa, 6 sccm : 149.39 GPa)따라 표면의 탄성에 큰 차이가 있음을 확인하였다. 이는 증착된 $HfO_2$ 시료들이 비정질 상태에서 $HfO_2$로 결정화되는 과정에서 산소가 증가할수록 박막의 defect이 감소되기 때문으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1103-1107
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• 2009

최근 기상이변에 따른 국지성 호우 등으로 인하여 지역별로 홍수량 차이가 많이 나고 있는 상황으로 유역내 중요시설물 및 인명의 보호를 위해서는 유역의 특성을 정확하게 반영한 홍수분석이 필수적인 실정이다. 유역 주요지점의 정확한 홍수량을 산정하기 위해서는 지역특성이 반영된 호우를 선정하고, 유출모의를 위한 유역특성이 잘 구현되어야 한다. 이를 위해서는 홍수량산정에 영향을 주는 매개변수의 정확한 산정이 필요하며 본 연구에서는 미공병단(US Army Corps)에서 개발하여 배포한 차세대 프로그램인 HEC-HMS(v3.3)를 이용하여 집중시간, 저류상수, Curved Number, 감수상수, 초기손실, 초기기저유량, Threshold 등 7가지 매개변수에 대한 최적화를 수행하였다. 종래에는 첨두홍수량을 중시하여 집중시간과 저류상수는 최적화하고 나머지 변수들은 실측치 및 계산값을 적용하였으나, 금번 연구에서는 첨두홍수량 및 총유출량 모두 관측값에 최대한 일치하도록 7가지 매개변수를 최적화하는 방안 및 최적화시 초기값 선정이 매개변수 최적화에 미치는 영향을 연구하였다. 매개변수 최적화 순서는 먼저 전체적인 평균유출량 또는 평균유출고가 실측치와 모의치 간에 일치하도록 CN, RC를 보정하고 다음 단계로 첨두발생시간이 일치하도록 Tc, K를 보정하고, 마지막으로 홍수 수문곡선의 형태를 결정하는 나머지 매개변수를 조정하여 전체적인 수문곡선의 형태와 첨두홍수량이 일치하도록 수행하였으며, Tc, K, CN 등의 중요 매개변수는 신뢰구간(계산치의 0.8${\sim}$1.2)을 설정하여 목적함수의 수렴을 유도하였다. 위를 이용하여 수렴된 매개변수들로 강우-유출 모의를 분석한 결과를 기존 홍수사상과 비교한 결과 상당히 근접한 결과를 도출할 수 있어, 매개변수는 7가지 모두에 대한 최적화를 가능한 것으로 연구되었으나 목적함수들의 수렴되는 과정에 대해서는 좀 더 심도있는 고찰이 필요할 것으로 판단된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1307-1312
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• 2015

As smart-phones become popular, mobile data traffic has been dramatically increasing and intensive researches on the next-generation mobile communication network is in progress to meet the increasing demand for mobile data traffic. In particular, heterogeneous network (HetNet) is attracting much interest because it can significantly enhance the network capacity by increasing the spatial reuse with macro and small cells. In the HetNet, we have several problems such as load imbalance and interference because of the difference in transmit power between macro and small cells and cell range expansion (CRE) can mitigate the problems. In this paper, we propose a new cell selection scheme with adaptive cell range expansion bias (CREB) for ultra dense HetNet and we analyze the performance of the proposed scheme in terms of average cell transmission rate through system-level simulations and compare it with those of other schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3A
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• pp.195-202
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• 2005

The third generation cellular system requires the seamless macro/micro mobility support. Mobile IP provides a simple and scalable macro mobility solution but lacks the support for fast handoff control in micro-domain. However, A lot of micro-mobility protocols have been proposed to complement the Mobile IP capability by providing the fast, seamless, and local handoff control. Cellular If also provides the seamless mobility support in limited geographical area. But semi-soft handoff mechanism of Cellular IP produces the packet loss and the duplication problem due to the difference of propagation delay between the new path and the old path. In this paper, we present an efficient handoff mechanism in micro-domain. The proposed handoff mechanism uses the SCD (Suitable Cross Delay) in order to minimize the packet loss and the duplication problem during the handoff. Also, the proposed mechanism is verified by the performance evaluation through the NS-2 Simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.63-66
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• 2015

As smart-phones become popular, mobile data traffic has been dramatically increasing and intensive researches on the next-generation mobile communication network is in progress to meet the increasing demand for mobile data traffic. In particular, heterogeneous network (HetNet) is attracting much interest because it can significantly enhance the network capacity by increasing the spatial resue with macro and small cells. In the HetNet, we have several problems such as load imbalance and interference because of the difference in transmit power between macro and small cells and cell range expansion (CRE) can mitigate the problems. In this paper, we propose a new cell selection scheme with adaptive cell range expansion bias (CREB) for ultra dense HetNet and we analyze the performance of the proposed scheme in terms of average cell transmission rate through system-level simulations and compare it with those of other schemes.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.1-8
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• 2011

With the development of next IT convergence technology and the construction of infrastructure for personalized services, the importance of services based on user's sensibility status and vital signal is being spotlighted. It is the most crucial factor for the strategy of sensibility engineering to investigate student's vital signal according to the sensibility. In this paper, we proposed the vital signal monitoring simulation system by the various visual stimulus. The proposed method obtained the student's vital signal by the various visual stimulus. And the power spectrum analysis using the fast fourier transform is evaluated the activity level between the sympathetic and the parasympathetic. The analyzed result is monitoring the sensibility by displaying the heath signal light. To evaluate the sensibility between the high school's students and the university's students, we conducted SD profile and paired T-tests so as to verify usefulness. This evaluation found that the difference of sensibility activity by positive and negative stimulus was statistically meaningful. Ultimately, this paper suggests empirical application to verify the adequacy and the validity.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.306.2-306.2
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• 2014

전자기기의 휴대성과 이동성이 강조되고 있는 현대사회에서 비휘발성 메모리는 메모리 산업에 있어 매우 매력적인 동시에 커다란 잠재성을 지닌다. 이미 공정의 한계에 부딪힌 Flash 메모리를 대신하여 10nm 이하의 공정이 가능한 상변화 메모리(Phase-Change Memory, PRAM), 스핀 주입 자화 반전 메모리(Spin Transfer Torque-Magnetic RAM, STT-MRAM), 저항 변화 메모리(Resistive Random Access Memory, ReRAM)가 차세대 비휘발성 메모리 후보로서 거론되고 있으며, 그 중에서도 ReRAM은 빠른 속도와 낮은 소비 전력, CMOS 공정 호환성, 그리고 비교적 단순한 3차원 적층 구조의 특성으로 인해 활발히 연구되고 있다. 특히 최근에는 질화물 또는 질소를 도핑한 산화물을 저항변화 물질로 사용하는 ReRAM이 보고되고 있는데, 이들은 동작전압이 낮을 뿐만 아니라 저항 변화(Resistive Switching, RS) 과정에서 일어나는 계면 산화를 방지할 수 있으므로 ReRAM의 저항 변화 재료로서 각광받고 있다. 그러나 Cell 단위의 ReRAM 소자를 Crossbar Array 구조에 적용시켰을 때 주변 Cell과의 저항 상태 차이로 인해 전류가 낮은 저항 상태(LRS)의 Cell로 흘러 의도치 않은 동작을 야기한다. 이와 같이 누설 전류(Leakage Current)로 인한 상호간의 간섭이 일어나는 Cross-talk 현상이 존재하며, 공정의 간소화와 집적도를 유지하면서 이 문제를 해결하는 것은 실용화하기에 앞서 매우 중요한 문제이다. 따라서, 본 논문에서는 Read 동작 시 발생하는 Cell과 Cell 사이의 Cross-talk 문제를 해결하기 위해 자가 정류 특성(Self-Rectifying)을 가지는 실리콘 질화물/알루미늄 질화물 이중층(Si3N4/AlN Bi-layer)으로 구성된 ReRAM 소자 구조를 제안하였으며, Sputtering 방법을 이용하여 제안된 소자를 제작하였다. 전압-전류 특성 실험결과, 제안된 구조에 대한 에너지 밴드 다이어그램 시뮬레이션 결과와 동일하게 Positive Bias 영역에서 자가 정류 특성을 획득하였고, 결과적으로 Read 동작 시 발생하는 Cross-talk 현상을 차단할 수 있는 결과를 확보하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.60-70
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• 2011

IPTV was introduced as the new growth engine of the broadcasting and telecommunications industry and has experienced a high growth rate as its subscribers exceeded 2 million in early 2010. However there have been some doubts on if the IPTV market will keep current growth drift. One of such suspicions is that IPTV market has not been developed by the competitiveness of IPTV industry itself. In addition, the recent slowdown of subscribers' growth and IPTV players' operating at a loss has been suggested as obstacles to the IPTV market growth. This sort of phenomenon has been brought about by ambiguous proposition of IPTV's own value as well as IPTV service positioning gap. To resolve these problems this study empirically investigates what customers want to get from IPTV service by analyzing switching value of IPTV subscribers. This study also identifies which values must be strategically considered to develop next generation IPTV services, in particular mobile IPTV services. Following the investigation, this study analyzes the possible positioning gap of mobile IPTV. Through this analysis, this study suggests which sort of service values need to be reconciled.