• Journal of KIISE:Databases
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• v.28 no.3
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• pp.458-467
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• 2001

Optimistic Two-Phase Locking(O2PL) performs as well as or better than the other approaches because it exploits client caching well and also has relatively lower network bandwidth requirements. However, O2PL leads to unnecessary waits, because, it can not be commit a transaction until the transaction obtains all requested locks. In addition, Optimistic Concurrency Control(OCC) tends to make needless aborts. This paper suggests an efficient optimistic cache consistency protocol that overcomes such shortcomings. Our scheme decides whether to commit or abort a transaction without wait and it adopts transaction re-ordering in order to minimize the abort rate. Our scheme needs only one version for each data item in spite of the re-ordering mechanism used. Finally, this paper presents a simulation-based analysis that shows superiority in performance of out scheme to O2PL and OCC.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.1013-1023
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• 2019

In content consumption environment with various live TV channels, VoD contents and web contents, recommendation service is now a necessity, not an option. Currently, various kinds of recommendation services are provided in the OTT service or the IPTV service, such as recommending popular contents or recommending related contents which similar to the content watched by the user. However, in the case of a content viewing environment through TV or IPTV which shares one TV and a TV set-top box, it is difficult to recommend proper content to a specific user because one or more usage histories are accumulated in one subscription information. To solve this problem, this paper interprets the concept of family as {user, time}, extends the existing recommendation relationship defined as {user, content} to {user, time, content} and proposes a method based on deep learning algorithm. Through the proposed method, we evaluate the recommendation performance qualitatively and quantitatively, and verify that our proposed model is improved in recommendation accuracy compared with the conventional method.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.5-9
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• 2006

Method for separation and quantification of methylxanthins, catechins, and theaflavins in Korean commercial teas (green, oolong, and black teas) was developed using reversed phase high-performance liquid chromatography (HPLC). After extraction with hot water, tea compounds were separated on Inertsil ODS-3v $(5\;{\mu}m)$ column, eluted with gradient of 7% acetonitrile and 93% of 20 mM phosphate buffer mixture for 7 min. Column effluent was monitored at 270 nm. This technique was effective for analyses of m methylxanthins, catechins, and theaflavins in teas and biological samples. In green and oolong teas, two kinds of methylxanthins and 7 of catechins were identified, whereas 4 theaflavins were only identified in black tea. Among seven catechins in green and oolong teas, EGCG showed highest amount, whereas ECG was highest in black tea. (theaflavins were found only in black teas) In all teas, theobromine content was lower than that of caffeine.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.52-52
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• 2018

목초지에서 비점오염원 유출특성은 가축밀도(stocking rate)와 방목형태(grazing management practice)에 기인하여 다르게 나타난다. 전통적인 방목형태는 한 대상지역에서 높은 가축밀도의 연속적인 방목(continuous grazing)을 취하는 것인데, 이 경우 토양압밀에 따른 강우의 침투량 감소, 가축의 배설물 축적 등으로 비점오염 유출량이 증가할 수 있으며, 식물의 재성장기간 부족으로 지속적인 방목지 운영이 어려울 수 있다. 순환방목(rotational grazing)은 이러한 연속적 방목 형태의 부정적인 영향을 개선하고자 대안으로 제시되었다. 방법은 구역을 나누고 초본식물의 생육상태를 고려하여 일정기간이 지나면 다른 구역으로 이동 시키며 방목하는 형태이다. 기존의 연구들은 단위 면적당 적정 가축밀도, 필드규모에서 방목형태에 따른 비점오염 유출특성에 초점을 두고 있으며, 결과들은 가축밀도의 영향보다는 방목형태에 의한 수문, 수질 영향이 더 크다고 지적하고 있다. 이에 본 연구에서는 이러한 가축밀도(Heavy vs Light) 및 방목형태(Continuous vs Rotational)가 유역의 비점오염 유출특성에 미치는 영향을 정량적으로 평가하고자, 미국 북텍사스 지역에 위치한 Clear Creek 유역을 대상으로 4개의 방목시나리오(heavy continuous[HC], light continuous[LC], multi-paddock[MP], no grazing)를 구성하고 Soil and Water Assessment Tool(SWAT) 모형에 적용하였다. SWAT 모형은 대상유역 내 4개의 방목지에서 측정한 토양수분 및 식물 바이오매스 자료, 유역 출구점에서 관측된 장기간의 수문 수질 자료를 이용하여 검증되었다. 연구결과는 순환방목(MP) 시나리오가 수질보호 및 토양침식 방지, 식생의 영양염류 흡수능력이 커지는 것과 같이 생태계서비스 기능의 개선 측면에서 최적의 방목형태(best grazing management)인 것으로 나타났으며, 이러한 결과는 가축밀도 보다는 방목형태에 기인한 것으로 필드와 유역스케일에서 동일한 결과를 보여주었다. 그러나 유역 내 목초지의 차지비율에 따라 순환방목 채택에 따른 비점오염 유출량의 감소효과는 다르게 나타나게 된다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.4
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• pp.105-118
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• 2006

The purpose of this research is twofold. The first is to develop the measures for evaluating performance of fingerprint sensor modules quantitatively and objectively. The second is to present the methodology for evaluating compatibilities among disparate fingerprint sensors. This paper focuses on the performance evaluation not of fingerprint authentication algorithm but of fingerprint sensors. Presented in this paper are several indicators and their measuring schemes such as the actual resolution of fingerprint images, the level of distortion by horizontal and vertical resolutions of fingerprint image, the intensity distribution for various illuminating conditions. Nine commercial sensor modules have been tested and the test results are expressed by using 95% confidence interval based on 50 acquired fingerprint images. The experimental results are compared with the manufacturer's sensor specification.

• Korean Journal of Optics and Photonics
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• v.31 no.6
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• pp.259-267
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• 2020

We evaluate the degradation of receiver sensitivity induced by direct and indirect exposure to solar irradiance in free-space optical communication systems. For this purpose, we calculate the variances of numerous noise components arising from solar irradiance, and then estimate the receiver sensitivity penalties for intensity-modulation/direct-detection and coherent systems. The results show that the penalties are less than 1.3 dB when indirect sunlight impinges on the detector, regardless of the system. However, the sensitivity penalties are estimated to be larger than 30 dB when the sunlight is directly incident upon the receiver. These penalties are barely reduced if we insert an optical polarizer, or if we adjust the bandwidth of an optical filter at the receiver to be as narrow as the signal's bandwidth.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.104-104
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• 2020

꼭두서니과 커피속 식물의주요 2차대사산물인 카페인은 커피나무, 카카오, 차나무 등에서 관찰되는 알칼로이드 화합물로 다른 식물의 발아 억제, 살충 기능이 알려져 있다. 인체에 있어 카페인은 각성효과가 있어 수면 장애나 불안을 유발할 수 있으며 섭취를 중단 시 졸음, 두통 등 금단 증상을 나타나기도 한다. 최근 다양한 식물 종과 부위를 이용한 차 문화가 확산되고 있는 바, 본 연구는 시중에서 판매되고 있는 커피 2종류과 녹차 2종류를 비롯하여 꽃차 37종류, 잎차 15종류, 씨앗차 2종류, 열매차 1종류 및 뿌리차 2종류를 대상으로 메탄올 추출 후 gas chromatography-mass spectrometry를 이용하여 카페인 함량에 대한 정성, 정량 분석을 수행하였다. 대조로 사용된 시판 커피 2개사 제품은 각각 1.18 mg/g, 35.94 mg/g의 caffeine 함량을 나타냈으며 시판 녹차 티백 제품 2종은 1.3 mg/g, 3.42 mg/g의 함량을 나타내었다. 조사된 37종의 꽃차 중에는 차나무 꽃차에서만 1.50 mg/g 수준의 caffeine이 검출되었을 뿐 국내 소비가 확대되고 있는 구절초, 국화, 금계국, 금목서, 금어초, 금잔화, 노랑코스모스, 당아욱, 도라지, 동백나무, 뚱딴지, 라벤다, 마리골드(노랑), 마리골드(주황), 매화, 맨드라미, 무궁화, 백목련, 벚나무, 복사나무, 비단향꽃무, 생강나무, 수레국화, 아까시나무, 연꽃, 유채, 작약, 장미, 진달래, 천일홍, 캐모마일, 패랭이꽃, 팬지, 해당화, 홍화, 히비스커스 등 36종에서는 카페인이 검출되지 않았다. 잎차의 경우 레몬그라스, 레몬밤, 로즈마리, 뽕나무, 세인트존스워트, 스테비아, 쑥, 애플민트, 연잎, 적양배추, 조릿대, 차수국, 티트리, 파인애플민트, 페퍼민트 등 평가된 15종류 모두에서 카페인이 검출되지 않았으며, 씨앗차인 펜넬 및 작두콩, 열매차인 진피차, 뿌리차인 자색당근과 비트차에서 역시 카페인이 검출되지 않았다. 이상의 결과에 기초할 때, 시판되는 다양한 식물 종과 부위를 이용한 차의 경우 대부분 caffeine을 함유하지 않음을 알 수 있었다.

• The Journal of the Acoustical Society of Korea
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• v.25 no.2
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• pp.88-95
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• 2006

In this Paper. a method for improving the performance of automatic speech recognition (ASR) system for conversational speech is proposed. which mainly focuses on increasing the robustness against the rapidly speaking utterances. The proposed method doesn't require an additional speech recognition task to represent speaking rate quantitatively. Energy distribution for special bands is employed to detect the vowel regions, the number of vowels Per unit second is then computed as speaking rate. To improve the Performance for fast speech. in the pervious methods. a sequence of the feature vectors is expanded by a given scaling factor, which is computed by a ratio between the standard phoneme duration and the measured one. However, in the method proposed herein. utterances are classified by their speaking rates. and the scaling factor is determined individually for each class. In this procedure, a maximum likelihood criterion is employed. By the results from the ASR experiments devised for the 10-digits mobile phone number. it is confirmed that the overall error rate was reduced by $17.8\%$ when the proposed method is employed

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.8
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• pp.1206-1211
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• 2015

Grape juice is consumed worldwide and studied due to the high antioxidant activities and contents. The color of grape juice is due to the presence of phenolic compounds such as anthocyanins. Therefore, color values can be an indicator of antioxidant capacities of grape juice. However, the correlation between color values and antioxidant activities in grape juice has not been well studied. In this study, the physicochemical characteristics and correlation between color values and antioxidant capacities of Korean red grape juices (five commercial juices from market and two juices prepared in the laboratory) were investigated to estimate antioxidant capacities. Antioxidant capacities were determined by 1,1-diphenlyl-2-picrylhydrazyl radical scavenging assay, ferric ion reducing antioxidant power assay, and oxygen radical absorbance capacity assay. Total phenolic contents, total flavonoid contents, and total anthocyanin contents, including five kinds of polyphenolic compounds, were examined by high performance liquid chromatography (HPLC). The results for physicochemical properties showed similar values, except titratable acidity. The color hue values of the prepared juices were higher than those of commercial juices, which was in contrast to the lower color intensity values (P<0.05). The Hunter L, a, and b values showed almost no difference between commercial and prepared juices. The antioxidant activities and total phenolic contents of commercial juices were higher than those of prepared ones. Gallic acid, catechin, and quercetin were confirmed by HPLC in all samples. The total phenolic and total flavonoid contents showed positive correlation with antioxidant activities. In addition, antioxidant activities and contents correlated with color values. Thus, estimation of antioxidant capacity could be feasible through the spectrophotometric measurement of color values.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.303-309
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• 1999

Mass mortality of the Manila clam, Ruditapes philippinarum has been reported all along the west and south coast of Korea for the past several years. As a pathogenic agent, Perkinsus sp., an endoparasitic protozoan has been identified in this study and believed to be responsible for the mass mortalities. Prevalence and infection intensity of Perkinsus sp. was investigated from a Manila clam population inhabiting at Komsoe Bay in the west coast where mass mortality of the clam has been reported. A total of 142 Manila clam, 50 oyster, Crassostrea gigas, 10 ark shell, Scapharca broughtonii, and 5 predatory gastropada, Rapana venosa were examined for the presence and the quantity of Perkinsus sp. Ray's fluid thioglycollate medium method (FTM method) with modified Mackin's infection intensity scale and Choi's quantitative method were used in detecting and quantifying the parasite. All individuals of R. philippinarum examined in this study were infected with Perkinsus sp., indicating $100\%$ prevalence while none of the oysters and the gastropods exhibited the parasite. Six to ten individual hypnospores of Perkinsus sp. were counted from the ark shells. The number of hypnospores in the clam tissues varied from 16,667 to 4,091,667, with a mean number of 1,077,628. Average infection intensity according to Mackin's was 2.87, indicating a moderate infection. A negative correlation was observed between the number of Perkinsus sp. in the tissue and the condition index, a ratio tissue wet weight to shell cavity volume. The clam size and the infection intensity in terms of total number of parasites were positively correlated; the bigger clam, the heavier infection. Such high number of Perkinsus sp. counted in the clams could be enough to cause physiological disturbance of clams, such as retarded growth and reproduction. It is also believed that such a high infection leads mortality of the clam via continuous draining of the energy by metabolic activities and reproduction of the parasites. Correlation between the condition index and the infection intensity observed in this study supports this hypothesis.