• Fibers and Polymers
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• 제4권3호
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• pp.114-118
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• 2003

The prepolymer and the final polyurethane (PU) block copolymer were synthesized by reacting 4,4-methylene bis(phenylisocyanate) with poly(tetramethylene glycol) and the prepolymer with 1,4-butanediol as a chain extender, respectively, to investigate the relation between phase separation and it's resulting properties. According to FT-IR data, the phase separation of hard and soft segments in the prepolymer and the PU block copolymer grew bigger by increasing the hard segment content, and the PU showed more dominant phase separation than the prepolymer. The heat of fusion due to soft segments decreased in both the prepolymer and the PU by increasing the hard segment content, whereas the heat of fusion due to hard segments increased in the PU did not appear in the prepolymers. The breaking stress and modulus of the prepolymer increased by increasing the hard segment content, and the elongation at break decreased gradually, and the PU showed the highest breaking stress and modulus at 58% hard segment content. However, the best shape recovery of the PU was obtained at 47% hard segment content due to the existence of proper interaction among the hard segments for shape memory effect. Consequently, the mechanical properties and shape memory effect of the PU were influenced by the degree of phase separation, depending on the incorporation of chain extender as well as the hard segment content.

• Journal of Information Processing Systems
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• 제10권4호
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• pp.543-554
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• 2014

It is difficult for mobile learners to maintain a high level of concentration when learning content for more than an hour while they are on the move. Despite the attention span issue, many m-learning systems still provide their mobile learners with the same content once used in e-learning systems. This has called for an investigation to identify the suitable characteristics of the m-learning environment. With this in mind, we have conducted a survey in hopes of determining the requirements for developing more suitable m-learning content. Based on the results of the survey, we have developed a content model comprised of two types: a segment type and a supplement type. In addition, we have implemented a prototype system of the content model for Apple iPhones and Android smartphones in order to investigate a feasibility study of the model application.

• 한국의류학회지
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• 제35권1호
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• pp.37-50
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• 2011

This study analyzed the content of special selling events in internet shopping malls to establish academic standards for special selling events as tools for sales promotions and to suggest systematic guidelines for marketers designing special selling events. Based on a content analysis, the titles of special selling events from four internet shopping malls selling women's apparel were analyzed. A total of 692 titles were analyzed. The results are as follow. First, the contents categories of special selling events could be classified into two groups such as 'theme' and 'tool'. Season, product characteristics, style, advice/information, brand, annual/social events, and marketing events were the main content categories that came under the 'theme' group; in addition, the price benefit, free offers, product mix, and marketing technique were the main content categories that came under the 'tool' group. Each main content category was subdivided into several segment content categories. Second, most of the titles were composed of more than two segment content categories that involved various information and benefits; however, the portion of titles composed of only theme related content categories or only tool related content categories was substantial. Furthermore, the theme related content categories were more than the tool related content categories. Third, the usage frequencies of the contents categories were analyzed. The upcoming season, single brand, sale/discount, item/material/color, special price/lowest price, and period/time/quantity limits were the segment content categories that held a high rank. Forth, most of the factors that evoked the unplanned purchases of consumers were related to the content categories of special sale events.

• 한국멀티미디어학회논문지
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• 제12권3호
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• pp.427-435
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• 2009

사용자들은 웹 콘텐츠의 세부 내용단위인 메뉴, 로그인, 뉴스, 동영상 등 다양한 아이템에서 자신이 홍미있는 아이템을 찾아 읽고 아이템에 연결된 하이퍼렁크를 클릭한다. 모바일 디바이스처럼 작은 스크린에서는 데스크탑 기반의 웹 콘텐츠를 동시에 보여주기 힘들어 사용자는 좌우 또는 상하 스크롤링을 통해 아이템을 찾아 헤매는 검색의 불편함이 발생한다. 사용자가 자주 사용하거나 또는 원하는 아이템을 찾아 먼저 표현하여 모바일 인터페이스 조작의 불편함을 감소시킬 수 있다. 그러기 위해 웹 콘텐츠는 세부 내용단위인 아이템 별로 세그먼트되어야 한다. 기존 대부분의 세그먼트 알고리즘들은 웹 콘텐츠의 HTML 코드와 모바일 사이즈에 기반하여 세그먼트하고 있어 다양한 아이템들이 구조적으로 더욱 복잡하게 형성되고 있는 현대의 웹 콘텐츠에서 내용 단위인 아이템 블록으로 세그먼트하는데 여러 어려움이 있다. 본 논문에서는 데스크탑 웹 콘텐츠에서 내용 단위에 기반한 아이템 블록 추출을 위한 세그먼트 알고리즘을 제안한다.

• 방송공학회논문지
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• 제23권6호
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• pp.813-823
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• 2018

끊김 없는 UHD 콘텐츠 스트리밍 서비스를 제공하기 위해서는 많은 가용 대역폭이 필요하다. 기존의 HTTP 적응적 스트리밍 방식은 정상 상태에서 가용 대역폭보다 낮은 품질의 비디오 세그먼트를 주기적으로 요청하여 다운로드 받는다. 정상 상태에서는 가용 대역폭과 콘텐츠의 인코딩 율에 차이에 따라 On-Off 구간의 패턴이 반복되어 발생하고, 반복적인 Off 구간에 의해서 대역폭을 효율적으로 사용하지 못하는 문제점이 있다. 지연과 손실률이 높고 대역폭 변화가 심한 무선 환경에서는 네트워크의 가용대역폭을 부정확하게 측정하기 때문에 문제점이 심화된다. 본 논문에서는 무선 환경에서 UHD 콘텐츠의 효율적인 대역폭 활용을 위한 HTTP 적응적 스트리밍의 세그먼트 스케줄링 기법을 제안한다. 제안하는 기법은 OFF 구간의 빈도수를 줄이기 위해 한 번의 요청 메시지에 여러 세그먼트를 동시에 요청하는 집단 세그먼트 방식이다. 실험을 통해서 제안하는 기법이 대역폭 이용율을 향상시키는 것을 확인 하였다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1998년도 가을 학술발표회논문집
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• pp.33-36
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• 1998

Segmented block copolyetheresters defined as copolymers having sequences of alternating polyester hard blocks and polyether soft blocks create labile physical cross-links upon crystallization of hard polyester blocks Since the nature of the physical interlocking is a crystallite formed exclusively from the crystallizable hard segment, the hard segment content (HSC) and hard segment length (HSL) will play an important role in determining the properties such as mechanical property and dynamic mechanical property. (omitted)

• 한국식품영양과학회지
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• 제27권4호
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• pp.653-658
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• 1998

In order to provide orange sac for off-season processing of sac-suspended orange juice, orange was treatee into intermediate production of orange sac and segment, stored at 2$0^{\circ}C$ during 3 months for assessment of sac-quality providing various processing conditions. Lowering the pH of syrup and sterilization temperature reduced the deterioration of sac quality in terms of intensity and destruction of sac. Sugar content of syrup had little relation with intensity of orange sac at pH 6.5, whereas in the range of pH 3.0~3.8, the increase of sugar content increased intensity of sac. The storage of segment form maintained better quality than that of sac form. The absorbance of syrup was linearly inverse to sac intensity. The deterioration of sac quality may be related to effulence of some materails in sac. Sac product sterilized at below $65^{\circ}C$ had possibility to be contaminated by microbes.

• 대한약리학회지
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• 제19권1호
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• pp.37-60
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• 1983

The uterus receives adrenergic terminals from the mesenteric ganglia and considerably large amount of catecholamines have been shown to be contained in this organ. On the other hand, the activities of epinephrine, norepinephrine or adrenergic nerve on uterine motility is so complicated that many controversial results have been reporter. Recently, a large number of reports concerning the changes of uterine catecholamines content have appeared, but little is known about the role of uterine catecholamines in their activities on uterine motility. The present experiments were undertaken to determine the significance of the intrinsic uterine catecholamines in the physiology of uterus. Female albino rabbits weighing approximately 2 kg were employed in this experiment. uterine strip3 were prepared and suspended in a constant temperature $bath(38^{\circ}C)$ containing 100 ml of Locke's solution aerated with 95% oxygen and 5% carbon dioxide. Spontaneous motility was recorded on a smoked drum with an isotonic lever. The catecholamines concentration of the uterus was determined according to the Procedure described of Shore and Olin (1958). Human uterus obtained from patients was also used to determine the catecholam ines content of myometrium. Followings are summarized results. 1) On the non-pregnant rabbit uterine strips, epinephrine and norepinephrine significantly elevated the tonus and stimulated the spontaneous motility. Pretreatment with dichloroisoproterenol(DCI), an adrenergic beta-receptor blocker, enhanced the stimulatory activity of epinephrine or norepinephrine. On the other hand, pretreatment with dibenamine, an adrenergic alpha-receptor blocker, rendered the uterine muscle to exhibit inhibition after the administration of epinephrine or norepinephrine. Following the treatment with both DCI and dibenamine, epinephrine or norepinephrine produced no appreciable effects on the spontaneous motility of the uterus. These results suggest there exist both alpha and beta-adrenergic receptors in the uterine muscle and the response to epinephrine of the former is predominant over that of latter in the non-pregnant uterus of rabbits. The total catecholamines concentration of the non-pregnant uterus was $351\;m{\mu}g/g$ and the fractional concentrations of epinephrine and norepinephrine were $125\;m{\mu}g/g(35.7%)$ and $226\;m{\mu}g/g$ respectively. It is interesting to note that the catecholamines content of uterus was characterized by a high fractional corcentration of epinephrine relative to norepinephrine. 2) On the pregnant rabbit uterine strips, the effects of epinephrine and norepinephrine varied according to the period of pregnancy. The response to epinephrine of adrenergic beta receptor of uterus increased during pregnancy, and the effect of catecholamine was inhibitory in the early pregnancy but became stimulatory as the pregnancy progressed. This stimulating action on the uterine motility was found to occur through the action of norepinephrine. The uterine catecholamines concentration was markedly reduced during pregnancy. The catecholamines concentration was started to decrease in the early pregnancy, reached the lowest level in the mid-pregnancy and then started to increaae again in the late pregnancy when the total catecholamines content became the highest level of all. This increase of catefholamines in late pregnancy was chiefly due to the increase of norepinephrine. These results suggest that the uterine motility may be related to the catecholamines content, especially norepinephrine content in the uterus. 3) Bilateral oophorectomy of rabbits results in a marked shrink of the uterus in size. The spontaneous motility of the uterine segment of these animals was very weak and irregular. Norepinephrine produced inhibitory effect, whereas epinephrine was stimulatory or inhibitory effect on the uterine segment. The total catecholamines tontent in whole uterus was markedly reduced. The injection of estrogen into the oophorectornized rabbit increased the weight of uterus to approximately three times of that of oophorectornized animal. The apontaneous motility and the response to epinephrine and norepinephrine of the uterine segment were greatly enhanced. Both epinephrine and norepinephrine produced a marked stimulatory effects of the uterine motility. The uterine content of catecholamines, particularly epinephrine, was markedly increased. The injection of progesterone into the oophorectornized rabbit increaeed the weight of uterus to approximately 2.5 times of that of eophorectornized animal. The spontaneous motility of the uterine segment was weak and irregular. Epinephrine produced stimulatory effect at high concentrations but norepinephrine always prcdnced inhibitory effect on the uterine segment. The uterine content of catecholamines, particularly of norepinephrine, was markedly reduced. These results suggested that ovarian hormones play an important role not only on the growth and spontaneous norepinephrine of uterus but also on the catecholamines content and responee to epinephrine and norepinephrine of the uterus. 4) The intraperitoneal injection of reserpine(3 mg/kg) into the non-pregnant, pregnant and oophorectornieed rabbits markedly decreased the uterine content of catecholamines, particularly of the norepinephrine. The stimulatory response to epinephrine and. norepinephrine of the uterine segment of these reserpinized ratbits was markedly reduced whereas the inhibitory response to these catecholamines was enhanced. This finding further support the close relationship between the uterine catecholamines content and uterine response to epineptrire and norepinephrine. 5) In the human uterus, the concentration of epinephrine was actrally greater than that of norepinephrine and it was significantly greater during the proliferative phase of the menstrtal cycle. In the human pregnant uterus, the concentrations of toth epinephrine and ncrefinephrine were markedly reduced and showed about 45 percent rednction after 6-8 weeks of ectopic Pregnancy. At full term ana during labor, the concentrations of epinephrine and norepinephrine at placental sites were less than those found in the non-pregnant group. Of interest was the finding that the norepinephrine concentration of uterus from toxemic patients was two and half times higher than that of lower uterine segment of the nontoxemic pregnant individuals. Also the epinephrine concentraticn was slightly increaeed.

• 말소리와 음성과학
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• 제14권3호
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• pp.27-40
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• 2022

이 연구는 한국어 음운구 억양 유형의 변별적 특성과 변이 조건을 밝히기 위한 목적의 일환으로 음운론적인 조건인 음절 수와 분절음 종류가 음운구 억양에 미치는 영향에 대해서 살펴보았다. 4음절을 기준으로, 음운구 억양은 LHLH를 기본형으로 설정할 수 있으며, 음절 수와 분절음 종류가 변이를 만드는 조건으로 작용한다고 할 수 있다. 음절 수는 억양을 곡선에서 직선으로 바꾸는데, 그 기준은 3음절 이하이다. 분절음은 음높이 대역과 음높이 변동에 영향을 미치는데, 첫 번째 분절음은 음운구 억양이 형성되는 음높이 대역에 영향을 미치고, 그 이하의 분절음은 음높이 변동에 영향을 미친다. 첫 번째 분절음이 [+기식성], [+긴장성], [+지속성]을 지니면 높은 대역, 그렇지 않으면 낮은 대역에서 억양이 형성된다. 높은 대역에서 실현되는 억양에서 두 번째 이하의 분절음이 [-기식성], [-긴장성], [-지속성]을 지니게 되면 음높이를 낮은 대역의 최하위까지 하강시키고, 낮은 대역에서 실현되는 억양에서는 [+기식성], [+긴장성], [+지속성]을 지닌 분절음이 LHLH의 두 번째 하강을 저지한다.

• 폴리머
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• 제24권2호
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• pp.149-158
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• 2000

흡유성이 우수한 발포 폴리우레탄(EPU)을 제조하기 위하여 soft segment로는 친유성 polyol인 polypropyleneglycol (PPG)를 사용하고 hard segment로는 toluenediisocyanate (TDI)와 $H_2O$를 사용하였다. Soft segment 함량이 흡유성과 발포체의 기계적 특성에 미치는 영향을 조사하기 위하여 PPG 평균 분자량((equation omitted) 1000, 2000, 3000)에 따라 one-shot법으로 EPU를 제조한 결과 PPG 평균분자량이 3000에서 1000으로 감소할수록 흡유량과 인장강도는 각각 1460%에서 3010%, 0.26 $kg_{f}$ /$cm^2$에서 0.55 $kg_{f}$ /$cm^2$로 동시에 증가하였다. Hard segment 함량비인 (isocyanate index, r=[NCO]/[OH] r이 1.0에서 1.2로 증가할수록 allophanate와 biuret 결합 형성에 기인하여 EPU의 인장강도가 0.56$kg_{f}$ /$cm^2$에서 0.95 $kg_{f}$ /$cm^2$로 증가하였으나, surfactant (S-A)의 함량은 1.0 pbw에서 2.5 pbw로 증가할수록 closed cell 구조의 형성으로 인하여 흡유량이 3634%에서 3312%로 감소됨을 알 수 있었다.