• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.42-48
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• 2004

Lean laminar premixed propane and methane flames which were anchored by a hydrogen-pilot flame in a tube were investigated experimentally. The flame shapes were observed by varying mean velocity from 10cm/s to 140cm/s and equivalence ratio from 0.45 to 0.8. In this study, behaviors of flames are divided into five regions such as tail-out, flash-back, flickering, stable and vibrating flames with respect to the mean velocity and the equivalence ratio. Although the flames are unstable in both the flickering and the vibrating region, they have different characteristics such as the frequency, sound generation and creation process of flame curvature. The flickering region exists near the flammability limit and the flame flickers in a frequency of about 10Hz. When flame front is bended, the propane flame front is straightened and the methane flame front is bended more by thermo-diffusive instability. In the vibrating region, the flame vibrates emitting audible sound in a frequency of about 100Hz. In the boundary of vibrating region, the vibration of flame changes between two modes such as single frequency vibration and dual frequency vibration. Increase and decrease of vibration in each mode are determined by thermo-acoustic instability.

• Fisheries and Aquatic Sciences
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• v.8 no.1
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• pp.17-26
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• 2005

The ultrastructure of germ cells during spermatogenesis and the structural changes in the epithelial cells of the seminal vesicle with testicular development in male Neptunea (Barbitonia) arthritica cumingii were investigated monthly based on electron microscopic and histologic observations. N. arthritica cumingii (Gastropod: Buccinidae) undergoes internal fertilization and possesses a modified type of spermatozoon, which is approximately 20$\mu$m long. The axoneme of the tail flagellum consists of nine peripheral pairs of microtubules and one central pair. Many spermatozoa occur in the acini of the testis in the ripe stage and are transported to the seminal vesicles in the accumulating phase. In males, the monthly gonadosomatic index began to increase in September and reached a maximum in February. Subsequently, it decreased rapidly after April. The testis of this species can be classified into four developmental stages: the active (August to September), ripe (October to July), copulation (April to July), and recovery (July to August) stages. Structural changes in the epithelial cells of the seminal vesicles of this species could be classified into three phases: (1) S-I (resting), (2) S-II (accumulating), and (3) S-III (spent) phases. The morphology and structure of the epithelial cells of the seminal vesicle differed in each phase; the cells were cuboidal, squamous, or columnar in the resting, accumulating, or spent phases, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.504-507
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• 2002

We investigated electro-optic and ionic properties of twisted nematic cells by using control of chiral pitch. These properties are observed in practical experiment and simulations. C-V and V-T curve characteristics were obtained from three types of cells with d/p. It is shown that d/p ratio of short cells exhibit faster response time improved by 20% than normal cell. Also, inter-gray response time is improved each rise time and decay time. And, the increase of saturation voltage is happened because of the small twist angel change from initial state at high voltage near 5V. To compensate for longer black level tail, gamma curve index was varied from g = 2.2 to g = 2.7 in module status. Additionally, adding chiral dopant into TN cells improved ionic characteristics such as increasing VHR, Ion density and DC Hysteresis were decreased..

• Journal of Aquaculture
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• v.12 no.1
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• pp.57-62
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• 1999

Experiments were performed to study the activity and fertility of grey mullet (Mugil cephalus) sperm after the courses of cold storage and cryopreservation. The head of spermatozoon showing spherical shape was sized $1.26{\pm}0.08 \{mu}textrm{m}$ in diameter and its nucleus contained numerous granular chromatins. Flagellum of tail showed typical 9＋2 structure. Preservation of grey mullet sperm was the most effective when it was stored with serum of the same species at $0^{\circ}C$ and sperm activity index was similar in egg-tris, 0.1 M, 0.3 M and 0.5 M glucose. When grey mullet sperm were cryopreserved in MFRS as diluent with 10% dimethyl sulfoxide was effective compared with other diluents. Some of post-thawed spermatozoa showed the enlarged head and ruptured plasma membrane compared with unfrozen spermatozoa.

• Journal of Astronomy and Space Sciences
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• v.39 no.2
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• pp.35-42
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• 2022

During their respective missions, the spacecraft Voyager and Cassini measured several Saturn magnetosphere parameters at different radial distances. As a result of information gathered throughout the journey, Voyager 1 discovered hot and cold electron distribution components, number density, and energy in the 6-18 Rs range. Observations made by Voyager of intensity fluctuations in the 20-30 keV range show electrons are situated in the resonance spectrum's high energy tail. Plasma waves in the magnetosphere can be used to locate Saturn's inner magnetosphere's plasma clusters, which are controlled by Saturn's spin. Electromagnetic electron cyclotron (EMEC) wave ring distribution function has been investigated. Kinetic and linear approaches have been used to study electromagnetic cyclotron (EMEC) wave propagation. EMEC waves' stability can be assessed by analyzing the dispersion relation's effect on the ring distribution function. The primary goal of this study is to determine the impact of the magnetosphere parameters which is observed by Cassini. The magnetosphere of Saturn has also been observed. When the plasma parameters are increased as the distribution index, the growth/damping rate increases until the magnetic field model affects the magnetic field at equator, as can be seen in the graphs. We discuss the outputs of our model in the context of measurements made in situ by the Cassini spacecraft.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.281-291
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• 2020

This study used Gauss-Poisson jump diffusion process on standard assets to estimate the statutory reserves of Variable Annuity (VA) guarantees specified in Korean bylaw of insurance supervision and calculated guarantee fees and risks based on the model to see the effect of considering the jumps. Financial assets, except KOSPI 200, have fat-tailed return distributions, which is an indirect evidence of discontinuous jumps. In the case of a domestic stock index and foreign stock indexes(Korean Won), guarantee fees and risks decrease when jumps are considered in models of underlying assets. This is explained by decreases in standard deviations after the jump diffusion is considered. On the other hand, in the case of domestic bond indexes and a foreign bond index(Korean Won), guarantee fees and risks tend to increase when jumps are considered. Results from a foreign stock index(US Dollar) and a foreign bond index(US Dollar) were opposite to those from the same kinds of Korean Won indexes. We conclude that VA guarantee fees and risks may be under or over estimated when jumps are not considered in models of underlying assets.

• Journal of Distribution Science
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• v.13 no.5
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• pp.53-60
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• 2015

Purpose - The purpose of this paper is to shed light on the importance of the slope and curvature of the volatility curve implied in option prices in the KOSPI 200 options index. A number of studies examine the implied volatility curve, however, these usually focus on cross-sectional characteristics such as the volatility smile. Contrary to previous studies, we focus on time-series characteristics; we investigate correlation dynamics among slope, curvature, and level of the implied volatility curve to capture market information embodied therein. Our study may provide useful implications for investors to utilize current market expectations in managing portfolios dynamically and efficiently. Research design, data, and methodology - For our empirical purpose, we gathered daily KOSPI200 index option prices executed at 2:50 pm in the Korean Exchange distribution market during the period of January 2, 2004 and January 31, 2012. In order to measure slope and curvature of the volatility curve, we use approximated delta distance; the slope is defined as the difference of implied volatilities between 15 delta call options and 15 delta put options; the curvature is defined as the difference between out-of-the-money (OTM) options and at-the-money (ATM) options. We use generalized method of moments (GMM) and the seemingly unrelated regression (SUR) method to verify correlations among level, slope, and curvature of the implied volatility curve with statistical support. Results - We find that slope as well as curvature is positively correlated with volatility level, implying that put option prices increase in a downward market. Further, we find that curvature and slope are positively correlated; however, the relation is weakened at deep moneyness. The results lead us to examine whether slope decreases monotonically as the delta increases, and it is verified with statistical significance that the deeper the moneyness, the lower the slope. It enables us to infer that when volatility surges above a certain level due to any tail risk, investors would rather take long positions in OTM call options, expecting market recovery in the near future. Conclusions - Our results are the evidence of the investor's increasing hedging demand for put options when downside market risks are expected. Adding to this, the slope and curvature of the volatility curve may provide important information regarding the timing of market recovery from a nosedive. For financial product distributors, using the dynamic relation among the three key indicators of the implied volatility curve might be helpful in enhancing profit and gaining trust and loyalty. However, it should be noted that our implications are limited since we do not provide rigorous evidence for the predictability power of volatility curves. Meaning, we need to verify whether the slope and curvature of the volatility curve have statistical significance in predicting the market trough. As one of the verifications, for instance, the performance of trading strategy based on information of slope and curvature could be tested. We reserve this for the future research.

• Journal of Korean Medicine Rehabilitation
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• v.21 no.1
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• pp.79-95
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• 2011

Objectives : This study was to investigate the antiarthritic effect of Hwallak-dan(Huoluo-dan) on the complete freund's adjuvant(CFA)-induced arthritis in Lewis rats. Methods : Arthritis was induced by intradermal injection of CFA into base of tail. Experimental groups divided into normal(n=10), control(n=10) and treated(n=10) group. Animals of control group received normal saline for twenty days, treated group received extracts Hwallak-dan(Huoluo-dan) for same duration, light mineral oil only injected non-arthritic rats were served as normal group. The incidence of arthritis and arthritic index were observed after treatment. Body weight, paw edema volume and thickness of ankle joint were measured at 0, 11, 14, 17, 20 days after treatment. White blood cell(WBC) counts in blood were analysed at 20 days after treatment and tumor necrosis $factor-{\alpha}(TNF-{\alpha})$, $interleukin-1{\beta}(IL-1{\beta}$), IL-6 contents in paw exudate were analysed by ELISA at 20 days after treatment. Histopathology on the ankle joint were performed at 20 days after treatment. Results : 1. Incidence of arthritis of treated group was 60% and control group was 100% at 20 days after treatment. 2. Arthritic index of treated group was significantly decreased compared with control group at 20 days after treatment. 3. Paw edema volume and thickness of ankle joint of treated group was significantly decreased compared with control group at 20 days after treatment. 4. Total WBC of treated group was significantly decreased compared with control group at 20 days after treatment. 5. Neutrophils of treated group was significantly decreased compared with control group at 20 days after treatment. 6. $TNF-{\alpha}$ content in paw exudate of treated group was significantly decreased compared with control group at 20 days after treatment. 7. $IL-1{\beta}$ content content in paw exudate of treated group was significantly decreased compared with control group at 20 days after treatment. 8. IL-6 content content in paw exudate of treated group was significantly decreased compared with control group at 20 days after treatment. 9. Histopathological arthritic index of treated group was significantly decreased compared with control group at 20 days after treatment. Conclusions : These results indicate that Hwallak-dan(Huoluo-dan) has inhibitory effect on the development and progression of CFA-induced arthritis in rats.

• Journal of Korean Society of Rural Planning
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• v.17 no.3
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• pp.81-90
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• 2011

The altitude criteria of 'Management of Mountains District Act' and 'National Land Planning and Utilization Act' are different because the adaptive reuse permissions on mountains district by two acts have been operated individually and each criteria has some problems for application. This study aims to suggest proposals for improvements of altitude criteria by two acts. The altitude criteria of the duel legal systems were researched by literature review and inherent issues were derived by interview with public officers and GIS tools applied to cases. The results are as follows : First, duel criteria systems need to be integrated based on the format by 'Management of Mountains District Act'. Second, the criteria index(50/100) by 'Management of Mountains District Act' need to be adjusted due to the preserved area ratio in mountains district and the each definition of 'the peak point of the mountain' and 'the tail of the mountain' can be changed as 'the highest point within the same slope(including ridge)' and as 'the average of the highest and the lowest point on boundary between the mountain district and the other land use district'. Third, the method of slope division may be determined by the conditions of local areas and the discrepancy between the two slopes in common boundaries must be adjusted. Finally, the maps containing preservation areas and development areas need to be notified.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.2
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• pp.280-287
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• 2001

These studies aimed to determine how lighting might be used to improve feed intake and reduce aggressive behavior in newly weaned pigs. To examine whether this objective could be achieved an experiment was conducted to compare performance, behavior and body condition of weaners over 17-45 days, provided similar lighting quality (i.e. color temperature, color rendering index and lighting distribution) after weaning that piglets experienced prior to weaning. Triphosphor (TP) lighting to simulate daylight was provided during the day while at night, Pascal red (PR) lighting was provided to simulate the night-light piglets previously had received from infrared heating lamps. This treatment was compared to weaners provided conventional cool-white fluorescent light during the day only. Weaners on treatment lighting from 17-45 days of age showed no improvement in body weight or feed conversion at 24, 31, 38 and 45 days compared to the controls. There was, however, a significant improvement (p<0.05) in feed intake in the first week of weaning for weaners provided TP/PR lighting. Over the first 3 days of weaning, pigs on TP/PR lighting showed an increase (p<0.05) in the incidence of ear chewing but reduced (p<0.05) levels of nosing the abdomen of other pigs and reduced (p<0.05) occurrences of being stood on by other pigs. Females exhibited more (p<0.05) mounting and nosing behaviors and rubbing the heads of other pigs than males. On the other hand, males engaged in more (p<0.05) fighting, nipping, ear chewing and standing on other pigs compared to females. Pigs provided PR lighting on the first night of weaning engaged in higher (p<0.05) incidences of nosing and tail sucking behaviors, more (p<0.05) head thrusting, fighting and ear chewing compared to control pigs. The body condition of weaners provided the TP/PR lighting treatment was significantly poorer (p<0.05) compared to weaners on control lighting. In conclusion there was no improvement in production performance of weaners provided new technology lighting apart from the improvement in feed intake in the first week weaners were exposed to the TP/PR lighting.