• Title/Summary/Keyword: Flow Transition

Search Result 865, Processing Time 0.023 seconds

The Study on the Increased Causes of Chloride ($Cl^{-}$) Concentration of the Samyang 3rd Pumping Station in Cheju Island (제주도 삼양 3수원지의 염소이온농도 상승 원인에 관한 연구)

  • 이성복;김구영;한소라;한정상
    • Journal of the Korean Society of Groundwater Environment
    • /
    • v.4 no.2
    • /
    • pp.85-94
    • /
    • 1997
  • The study is aimed to find out the causes of rapidly increasing chloride (Cl$^{-}$) concentration of the Samyang 3rd pumping station originated from coastal springs of Cheju since January 1996. The study results show that it was caused by following complicated natural and anthropogenic effects. Due to severe draught in 1996 with total rainfall of only 41.7% of annual mean of the last 36 years (1991 to 1995), it creates firstly), significant decrease of the spring discharges as well decline of the groundwater level at the site . Sea water level was in general 4.4 cm to 12.4 cm higher than the groundwater level of the site during 2 to 3.8 hours at each high tide. Those higher potential head of sea water motivates the sea water intrusion into the fresh water lens through the permeable clinkers and fracture zones situated beneath the existing grouted zone which was installed to a maximum 10 m below the ground water surface, The repeated expansion and contraction of the fresh water lens occurred by periodic changes of the sea water level at high and low tide accelerates secondly the enlargement of the transition zone between the fresh and sea water at the site. The decrease of recharge amount by rainfall shortage creates thirdly the reverse flow at the interface of sea water and groundwater. The repeated groundwater extraction of 2790${\pm}$450 $m^3$d$^{-1}$ at the time of low tide, when the fresh water lens of the sire is under the contraction stare, makes additional drawdown of the ground water level and induces the upconing of salt water into the fresh water lens. The duration of spring discharge whose Cl concentration is less than 150 mg/1 at the low tide measured at the nearby springs was about two hours with discharge rate of 532 $m^3$d$^{-1}$ and after that Cl$^{-}$ concentration is increased up to more than 1900 mg/ι.eased up to more than 1900 mg/L.

  • PDF

Rheological Properties of ${\beta}-Glucan$ Isolated from Non-waxy and Waxy Barley (메성 및 찰성보리 ${\beta}-Glucan$의 리올로지 특성)

  • Choi, Hee-Don;Park, Yong-Gon;Jang, Eun-Hee;Seog, Ho-Moon;Lee, Cherl-Ho
    • Korean Journal of Food Science and Technology
    • /
    • v.32 no.3
    • /
    • pp.590-597
    • /
    • 2000
  • The rheological properties of ${\beta}-glucans$ isolated from non-waxy and waxy barley were investigated. ${\beta}-Glucan$ solutions showed pseudoplastic properties and their behaviors were explained by applying Power law model in the range of concentrations$(1{\sim}4%)$ and temperatures$(20{\sim}65^{\circ}C)$. The effects of temperature and concentration on the apparent viscosity at $700\;s^{-1}$ shear rate were examined by applying Arrhenius equation and power law equation, and their effect was more pronounced in waxy ${\beta}-glucan$ solutions. The activation energy for flow of ${\beta}-glucan$ solutions decreased with the increase of concentration, and the concentration-dependent constant A increased with the increase of temperature. The intrinsic viscosity of waxy ${\beta}-glucan$ was higher than that of non-waxy ${\beta}-glucan$. The transition from dilute to concentrate region occurred at a critical coil overlap parameter $C^*[{\eta}]=0.02.$ The slopes of non-waxy and waxy ${\beta}-glucan$ at $C[{\eta}] were similar, but the slope of waxy ${\beta}-glucan$ at $C[{\eta}]>C^*[{\eta}]$ was higher than that of non-waxy ${\beta}-glucan$. Dynamic viscoelasticity measurement showed that cross-over happened, and storage modulus was higher than loss modulus at frequency range above cross-over. ${\beta}-Glucan$ solutions formed weak gels after stored for 24 hr.

  • PDF

Characteristics of NO Oxidation Using NaClO2 (NaClO2를 이용한 NO 산화 특성)

  • Lee, Kiman;Byun, Youngchul;Koh, Dong Jun;Shin, Dong Nam;Kim, Kyoung Tae;Ko, Kyoung Bo;Cho, Moohyun;Namkung, Won;Mok, Young Sun
    • Korean Chemical Engineering Research
    • /
    • v.46 no.5
    • /
    • pp.988-993
    • /
    • 2008
  • The characteristics of NO oxidation using sodium chlorite ($NaClO_2$) powder have been investigated by a flow type packed-bed reactor, where the reaction temperature and the space velocity are varied in the range of $20{\sim}230^{\circ}C$ and $0.4-2.2{\times}10^5hr^{-1}$, respectively, and the simulation gas mixtures are composed of NO (0~200 ppm), $NO_2$ (0-200 ppm), $O_2$ (0~15%) and $H_2O$ (0~15%) within $N_2$ balance. It has been found that the oxidation efficiency of NO depends greatly on the reaction temperature, exhibiting the existence of critical reaction temperature at about $170^{\circ}C$ where the oxidation efficiency of NO is maximized and then abruptly decreased with further increase of reaction temperature, resulting in being negligible over $190^{\circ}C$. Such a behavior in the oxidation efficiency has been originated from the phase transition of $NaClO_2$ at about $170^{\circ}C$ to form $NaClO_3$, and NaCl which are chemically inactive toward the oxidation of NO. The chemical reaction of NO with $NaClO_2$ has been observed to produce $NO_2$, ClNO and $ClNO_2$, whereas that of $NO_2$ only OClO species. Additionally, we have also observed that the introduction of $O_2$ and $H_2O$ has little influence on the oxidation of NO.

Pictorial Record of 'Joseon's Exhibitions of Chinaware and Wooden Works' - Pictorial Record of the Exhibitions of Korean Chinaware and Wooden Works Held in Tokyo, Japan in the 1930s - (『조선도자목공전관(朝陶磁木工展觀)』 도록 - 1930년대 일본 동경에서 개최된 한국 도자기, 목공예 전시회 도록 -)

  • Kim, Sang-yop
    • (The)Study of the Eastern Classic
    • /
    • no.32
    • /
    • pp.425-441
    • /
    • 2008
  • Most of Korea's Kyungmaedorock(auction book: 競賣圖錄) and pictorial record of exhibitions in the modern times were usually published in the 1930s. Although 1930s were periods of the Great Depression when economic slump continued because of the aftereffect of the slump in the stocks issued by the US in 1929, during this period, Japan began regular continental invasion starting from invasion of the northeastern area of China. To curio dealers, the 1930s were 'boom period of curio transaction' and in urban cultural aspects, the period is evaluated as the one when the first step of modernism was formed. Collection, photo-printing and arrangement of the data related to modern exhibitions including the Auction Book being published at that time are very important because they enable us to know characteristics of fine arts in the transition period from paintings & writings to fine arts in addition to enabling us to revert the circulation history of our paintings & writings and curios. Furthermore, these data will become important data for reconstitution of the circulation history of the Eastern Asia's modern art works. Although the pictorial record of Joseon's Exhibitions of Chinaware and Wooden Works(朝鮮陶磁木工展) is a small and thin one, it records our country's high level chinaware and wooden works. Although we can't know the exact time for 'Joseon's exhibitions of chinaware and wooden works', they are assumed to have been held in Tokyo, Japan in the 1930s and there seems to have been sale of works, too. As such, studies of the books such as the auction book and exhibitions under Japanese imperialism have the first importance in the fact that through which we can examine the course of outflow of our art works to Japan. Furthermore, they can be studies of art-sociology that examine flow and phase of recognition and taste of art works of those days. And from now on, comparative studies of auctions and exhibitions being held in Japan such as Tokyo, Osaka and etc. as well as art markets in Seoul during modern times would also be necessary.

A Study on the Changing Perception of Queen Mother of the West from the Perspective of Yin-Yang Theory (음양론 관점에서 본 서왕모(西王母) 인식 변화 고찰)

  • Jo Min-hwan
    • Journal of the Daesoon Academy of Sciences
    • /
    • v.42
    • /
    • pp.45-73
    • /
    • 2022
  • The phenomenon of veneration for Queen Mother of the West [西王母 Chn: Xiwangmu Kr: Seowangmo] is a 'cultural flow' that has garnered great interest not only in China but also in Korea for many years. To properly understand the cultural trend regarding the Queen Mother of the West, it is essential to view the related mythology as it corresponds to East Asian women as well as the transformation of society's view of women. In addition to the outcomes that result from the establishment of a patriarchal society, the relationship between goddesses and gods gradually becomes a relationship of discrimination based upon differences. Accordingly, as women change into objects that are given meaning rather than subjects that give meaning, the de-sacredization of the goddess occurs. This paper focused on the changes in the perception of the Queen Mother of the West from the view of Yin-Yang theory. This approach shows a transition process of transforming wherein she has morphed into an assistant or spouse of a god as part of a trend that deemphasizes the divinity of her as a stand-alone goddess. Yin-Yang theory is the key to understanding culture, history, and art as well as Chinese philosophy. This key can be further applied to the theme of women in mythology. What is particularly noteworthy about the process by which the Queen Mother of the West was defined as a goddess is that she was original described as half-human and half-beast and yet by the time her depictions became fully human and fully woman, she was described instead as an absolute beauty endowed with great artistic talent. In this paper, it will be revealed that the perception of the Queen Mother of the West, as an absolute beauty and artistic talent, is embedded with the male societal desire for an image of the feminine as understood via Yin-Yang theory. Queen Mother of the West as she was depicted in the Classic of Mountains and Seas (山海經 Chn: Shanhaijing Kr: Sanhaegyeong) had a half-human half-beast form that instilled people with fear of disasters and punishments from heaven. However, in the Han Dynasty, her religious significance became that of an object to ward off evil and attain blessings. By the time of the novel, Tales of the Strange (志怪小說 Chn: Zhiguaixiaoshuo Kr: Jigoesoseol), from the Wei, Jin, Southern and Northern Dynasties, she was transformed into a goddess in the image of beautiful woman in charge longevity and immortality. From the perspective of Yin-Yang theory, the changes in the perception of Queen Mother of the West was found to contain the following meaning: as an extension of the establishment of a patriarchal system and subordinate laws, her new form was made to be pleasing to the male gaze and Yin-Yang theory was brought in to support those changes later.