• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.477-482
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• 2020

The human visual cortex has the characteristic that reacts sensitively to stimuli with special directional or temporal frequency changes while it is insensitive to selective stimuli of spatial phases. In this paper we implemented the model of complex cell using an image estimation iterative algorithm by Gabor wavelet transform. The performance of implemented model evaluated the consistency between the physiological experimental results in related papers. The implemented model is limited in the complete model of the receptive field in the retina where simple cells and complex cells are distributed together. But the implemented model express the reaction of the complex cells from the point of view of the detection of corners and edges.

• Journal of IKEEE
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• v.24 no.4
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• pp.1074-1080
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• 2020

This paper proposes a digitally controlled buck converter insensitive to process, voltage and temperature and capable of three modes of operation depending on the state of the output voltage. Conventional digital-controlled buck converters utilized A/D converters, counters and delay line circuits for accurate output voltage control, resulting in increasing the number of counter and delay line bits. This problem can be resolved by employing the 8-bit and 16-bit bidirectional shift registers, and this design technique leads a buck converter to be able to control duty ratio up to 128-bit resolution. The proposed buck converter was designed and fabricated with a CMOS 180 nano-meter 1-poly 6-metal process, generating an output voltage of 0.9 to 1.8V with the input voltage range of 2.7V to 3.6V, a ripple voltage of 30mV, and a power efficiency of up to 92.3%. The transient response speed of the proposed circuit was measured to be 4us.

• Journal of the Korea Society of Computer and Information
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• v.26 no.7
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• pp.1-7
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• 2021

In this paper, we propose a feature selection technique for multi-label classification. Many existing feature selection techniques have selected features by calculating the relation between features and labels such as a mutual information scale. However, since the mutual information measure requires a joint probability, it is difficult to calculate the joint probability from an actual premise feature set. Therefore, it has the disadvantage that only a few features can be calculated and only local optimization is possible. Away from this regional optimization problem, we propose a feature selection technique that constructs a low-rank space in the entire given feature space and selects features with sparsity. To this end, we designed a regression-based objective function using Nuclear norm, and proposed an algorithm of gradient descent method to solve the optimization problem of this objective function. Based on the results of multi-label classification experiments on four data and three multi-label classification performance, the proposed methodology showed better performance than the existing feature selection technique. In addition, it was showed by experimental results that the performance change is insensitive even to the parameter value change of the proposed objective function.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.148-148
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• 2020

산업의 고도화가 진행됨에 따라 화학원료의 사용이 증가하고 있고 독성을 가진 화학물질이 하천으로 유입되는 사고가 빈번하게 발생하고 있다. 수환경으로 유입되는 유해화학물질은 주로 무색무취의 물질들로 사고가 발생하더라도 초기 발견이 어려워 어류폐사를 유발하거나 취수시설에서 용수로 취수되는 경우가 발생하기 때문에 이에 대한 대응책 마련이 필수적이다. 하천에 유입된 오염물질의 거동을 신속하게 예측하기 위해 1차원 오염물질 추적 모형이 활용되는데, Fickian 이송-분산 모형(Fickian Advection-dispersion equation model; FADE)이 주로 사용되고 있다. 하지만 FADE는 오염물질이 하천 저장대에서 지체되는 현상을 반영하지 못하기 때문에 농도곡선의 왜곡도를 구현하지 못하는 단점을 가지고 있다. 따라서 본 연구에서는 하천저장대모형(River Storage Model; RSM)을 개발하고 이를 국가하천인 감천에 적용하였다. 본 연구에서 개발한 RSM은 분산계수, 본류대 면적, 저장대 면적, 저장대 교환계수의 네 가지 매개변수를 통해서 하천의 물질 저장 및 교환 특성를 구현한 non-Fickian 모형으로서, 생화학반응, 휘발, 흡·탈착항을 추가하여 유해화학물질의 혼합 거동을 정확하게 모의할 수 있도록 개발하였다. 저장대 모형의 매개변수를 산정하기 위해서 하천 유량과 지형자료를 기반으로 HEC-RAS를 모의하여 계산된 수리특성을 입력변수로 사용하였다. 저수기, 평수기, 풍수기 유량을 기준으로 세 경우의 시나리오 모의를 수행하였는데, 5ton의 톨루엔이 김천산업단지에서 감천으로 유입된 경우 약 20km 하류에 위치한 취수장에서 톨루엔의 농도변화를 예측했다. 보존성 물질에 대한 모의 결과, 풍수기의 경우 저수기에 비해 유속이 크기 때문에 취수장에서 20.56시간 먼저 기준농도에 도달하고, 7.21시간 더 짧게 머무는 것으로 나타났다. 유해화학물질의 반응특성에 대한 민감도 분석을 시행한 결과, 생화학적 반감기가 18.98시간보다 길고, 옥탄올-물 분배계수가 2.267 이하인 물질은 생분해 및 흡·탈착 반응에 둔감한 것으로 나타났다. 1m 수심 기준 0.114m/s 이하 유속에서의 하천 수리조건에서는 화학물질의 휘발성을 무시할 수 있는 것으로 밝혀졌다.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.222-229
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• 2024

As the operating condition for the penetrating missile has been more advanced, the survivability of main charge has been strongly required when the warhead impacts the target. Lots of efforts to desensitize explosives such as the development of insensitive molecular explosives or optimizing plastic-bonded explosives(PBX) systems has been made to enhance the survivability of main charge. However, these efforts face their limits as the weapon system require higher performance. Herein, we suggest a new strategy to secure the survivability of main charge. We applied structurally supportable aluminum honeycomb(HC) structure to cast PBX. The aluminum HC structure reinforces the mechanical strength of cast PBX and helps it to withstand external pressure without the reaction like detonation. In this study, impact resistance character, shock sensitivity and internal blast performance of PBXs reinforced with HC structure were investigated according to the application of aluminum HC structure. The newly suggested aluminum HC structure applied to cast PBX was proved to be a promising manufacturing method available for high-tech weapon systems.

• Current Research on Agriculture and Life Sciences
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• v.11
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• pp.61-70
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• 1993

We investigated the effects of shading on the plant growth, flowering and the bulbil formation of Lilium species. As the shading treatment, we used full sunlight and various light intensity, 30%, 50%, 75%, 90% compared to full sunlight with shading net. The results obtained were as follows. The flowering rate and flower number of 'Roma' and 'Georgia' were not effected by various shading treatment. Days to flower in 'Roma' and Tiger lily showed similiar tendency like this. One of the shading effect was stem elongation of 'Connecticut king' markedly reduced compared with other cultivars in flowering rate and flower number. Leaf number of all cultivars was not consistent in tendency. But leaf number of Tiger lily and 'Connecticut king' reduced. The tendency of other experimented Lilium species weren't consistent. Bract leaf number reduced gradually as shading rate increased, plant height and internode length increased. Especially the height of 'Georgia' showed eminant increase compared with others. Total number and weight of bulbil of 'Enchantment' and Tiger lily reduced as shading rate increased.. But bulbil weight from bract part of 'Enchantment' in creased. The bulbils of 'Connecticut King' and 'Roma' appeared only on upper stem parts when treated serious shaded conditions, 75% and 90%. Only 'Connecticut King' and 'Enchantment' showed leaf emergence from bulbil among the L. elegans species.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.306-316
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• 2015

An experiment in a controlled environment was conducted to evaluate the genotypic differences of grain yield and yield-related elements of rice under elevated air temperature. Eight rice genotypes included in three maturing group (early, medium, and medium-late maturing group) were grown with 1/5,000 a Wagner pots at four plastic houses that were controlled to the temperature regimes of ambient temperature (AT), $AT+1.5^{\circ}C$, $AT+3.0^{\circ}C$, and $AT+5.0^{\circ}C$ throughout the rice growing season in 2011. Ripened grain ratio and 1000 grain weight showed the most susceptible and tolerant responses to elevated air temperature, respectively. The grain yield reduction was attributable to the sharp decrease of ripened grain ratio. Grain yield was significantly decreased above the treatment of $AT+1.5^{\circ}C$ and $AT+3.0^{\circ}C$ in early maturing group and the others, respectively. Highly correlation to average temperature from heading to 20 days was revealed in yield (r = -0.69), ripened grain ratio (r = -82), fully-filled grain (r = -70), and 1000 grain weight (r = -0.31). The responses of yield and yield-related elements except number of spikelets and panicle to elevated air temperature were fitted to a logistic function. The parameters of logistic function for each elements except grain yield could not be applied to the other varieties. In conclusion, yield and yield-related elements responded differentially to elevated air temperature according to maturity groups and rice varieties. Ongoing global warming is expected to decrease the grain yield not only by decreasing the grain weight but also decreasing the ripened grain ratio in the future. However, the yield reduction would be mitigated by adopting and/or breeding the less sensitive varieties to high temperature.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2369-2379
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• 2013

A CMOS x-ray line scan sensor which is used in both medical imaging and non-destructive diagnosis is designed. It has a pixel array of 512 columns ${\times}$ 4 rows and a built-in DC-DC converter. The pixel circuit is newly proposed to have three binning modes such as no binning, $2{\times}2$ binning, and $4{\times}4$ binning in order to select one of pixel sizes of $100{\mu}m$, $200{\mu}m$, and $400{\mu}m$. It is designed to output a fully differential image signal which is insensitive to power supply and input common mode noises. The layout size of the designed line scan sensor with a $0.18{\mu}m$ x-ray CMOS image sensor process is $51,304{\mu}m{\times}5,945{\mu}m$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.391-395
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• 2012

We present a continuous cell separator that achieves density-dependent and size-independent cell separation based on the net force of gravity and buoyancy forces on the cells in dissimilar density fluids. Previous cell separators are, based on the size or dielectrophoretic property of the cells and, are suitable for size-dependent and density-independent cell separation. However, these properties can make it difficult to collect the same types of cells with the same density but with size variations. The present separator, however, is capable of collecting the same types of cells based on the cell density in the fluid. Regardless of cell size, the proposed chip isolates low density cells, (white blood cells, or WBCs) at the upper outlet while obtaining high-density cells (red blood cells, or RBCs) from the lower outlet based on density. Efficiency levels for separation of WBCs and RBCs were $90.9{\pm}9.1%$ and $86.4{\pm}1.99%$, respectively. The present separator therefore has the potential for use in the pretreatment of whole blood.

• Journal of dental hygiene science
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• v.17 no.1
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• pp.46-55
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• 2017

Many people in Korea suffer from a fear of dental treatments; however, only a few studies have focused on this population. This study assessed the effectiveness of cognitive behavioral therapy (CBT) and its interventions in reducing dental anxiety, especially when administered by trained dental staff. Using case studies, the authors analyzed the content of each session and examined the process of reducing dental anxiety. First, the authors observed that the results of both dental fear scale and subjective unit of disturbance decreased significantly with changes in cognitive distortions related to dental anxiety and that rapid improvements were noted after two therapy sessions. Second, the study reported that practicing relaxation (deep-breathing) and muscle relaxation techniques; using hand signals to indicate anxiety or discomfort; establishing an empathic relationship with the therapist; making an anxiety list; and graded insensitive and exposure along with rehearsal, were effective in coping with dental anxiety and in changing negative thoughts towards the dentist. Third, a simple cognitive behavioral intervention can be effective in reducing dental anxiety. In summary, a short-term, five-session psychological intervention with CBT produced a sustained decrease in the symptoms of dental anxiety, allowing the patients to receive the required procedures. The authors discussed the study limitations and the implication of their results on future research.