• Magazine of RCR
• /
• v.18 no.1
• /
• pp.40-44
• /
• 2023

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.6
• /
• pp.2317-2328
• /
• 2013

In this study, the effect of wave chamber slab on wave pressure along the first and second wall of the perforated caisson breakwater was investigated by performing physical experiment. The experiment was performed without and with the wave chamber slab of the perforated caisson by varying the front wall porosity. The discrepancy in magnitudes of the measured wave pressure along the both walls of the perforated caisson was apparent according to the existence of the wave chamber slab as significantly greater pressures were acquired for all the test cases when the wave chamber was closed upward by the slab. As a result, the magnitudes of the total wave force calculated by integration of the measured wave pressure also were much larger for the caisson breakwater having the wave chamber slab, exceeding the value based on the well known Takahashi's formula (Takahashi and Shimosako, 1994). With respect to the porosity of the front wall, meanwhile, higher pressures were obtained with a larger porosity, at both the first and second wall of the breakwater.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.13 no.4
• /
• pp.263-272
• /
• 2001

Recently, some attempts to construct slit caisson-type breakwaters are made in Korea. Since slit caisson-type breakwaters are suitable for relatively deep sea areas, a lot of theoretical and experimental researches have been performed. In this study, the reflection characteristics of vertical slit caisson breakwaters are investigated based on the measured data in two-dimensional hydraulic model tests with irregular waves. The experiments were conducted for various cases; variation of porosity of perforated-wall, width of wave chamber, number of slits for single-and double-chamber, respectively. It is found that in the case when the wave steepness (H/L$_{s}$ ) is small, the reflection coefficients are large. The existing researches have shown that the wave reflection is minimized when the nondimensional width of wave chamber B/L is about 0.2~0.25 for the regular waves. However, for the irregular waves the reflection is lowest when $B/L_2$, is 0.13~0.15. For a same porosity condition, the wave dissipation is stronger as the width of s1it is larger. The double-chamber caisson is superior to single- chamber caisson in the wave dissipating effects.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.27 no.3
• /
• pp.238-242
• /
• 1982

The growth of spike, internode and leaf sheath in winter wheat(Tritican vulgale Vill.) was investigated by measuring them 10 times from April 15 to May 30, with 5 days intervals, in 1980. The variety used was Glumil(Suweon #215) which was newly developed at Wheat and Barley Research Institute in Suweon, Korea. During the periods investigated, the spike elongated from 0.6cm to 8.3cm. The spike began to elongate rapidly from 20 days before heading (April 25) and finished nearly off the elongation at 5 days before heading (May 10). The length of the spike showed highly significant correlation with that of 3rd internode ($r=0.974^{***}$), and. with that of first leaf sheath($r=0.954^{***}$) from the top of wheat plant. Correlation between the length of the 3rd internode and that of the first leaf sheath was also very high($r=0.995^{***}$). A major elongation of the spike occurred concurrently with the elongation of the third internode and with that of the first leaf sheath.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.30 no.3
• /
• pp.314-319
• /
• 1985

In order to observe the differences of several characters related to earliness, seven barley varieties were tested under two different photoperiodic conditions. Final leaf number per main stem under long day did not vary among varieties, but ranged 6 to 7 in early group and 9 to 10 in late group under shortday. Shoot apex of early varieties, Jogangbori and Oweolbori reached to X stage at 24 days, but that of late variety, CI 15446 did to X stag at 32 days after transplanting under short day. Spike length reached to maximum length at 39 days in early group, but at 51 days in late group. Saeolbori, CI 15446 and Hangmi were photo-sensitive, but Jogangbori and Oweolbori were photo-insensitive. Therefore, the photoperiodic response to short day was most responsible to heading time. Those results showed that early heading varieties had the characteristics with less variation of final leaves, less retardation of shoot apex development and spike elongation, and shorter period to flag leaf emergence under short day.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.178-178
• /
• 2020

본 연구에서는 벼 생육시기별로 염수 관개가 벼 작물에 미치는 생육 영향정도(민감도)를 평가하기 위하여 벼 재배실험(포트실험)을 수행하였다. 벼 재배실험은 일반 논토양(삼광벼)과 간척 논토양(신동진벼)을 대상으로 하였고, 벼 생육시기는 이앙기~활착기, 활착기~유수형성기, 유수형성기~수잉기, 수잉기~출수기, 등숙기의 5단계로 구분하였다. 벼 재배는 3반복 실험을 위해 총 126개의 포트(Φ215×Φ170×210mm(H))를 조성하여 5월 20일에 1주 3본으로 이앙을 하였다. 물 관개방식은 생육시기별로 염도를 1,000, 1,500, 2,000, 2,500 ppm으로 조절한 각각의 염수를 관개하고, 그 이외의 기간에는 담수(지하수)를 관개하였다. 벼 생육시기별로 염수 관개에 의한 벼 생육에 대한 민감도를 평가하고자 벼의 초장, 분얼수, 수확량을 조사하였다. 간척 논토양에서 초장, 분얼수는 생육초기인 이앙기의 염수에 의해 가장 민감하게 영향을 받는 것으로 나타났고, 수확량은 이앙기, 분얼기, 유수형성기 순으로 민감하게 영향을 받는 것으로 나타났다. 일반 논토양에서는 초장, 분얼수는 생육시기에 따른 염수관개에 의한 영향이 크지 않았으며, 수확량은 염분농도에 관계없이 이앙기, 분얼기, 유수형성기 순으로 염수에 의해 민감하게 영향을 받는 것으로 나타났다. 이러한 결과는 다수의 선행연구(Hassen Ebrahimi 등, 2011)의 벼 생육기인 분얼기, 유수형성기의 염수 관개가 수확량에 가장 많은 영향을 받는 결과와 일치하였다. 일반 논토양과 간척 논토양 모두 이앙기, 분얼기, 유수형성기 순으로 염수 관개에 민감한 영향을 나타내고 있으며, 특히 염분 배경농도가 높은 간척토양은 저농도의 염수에서도 민감한 반응을 보이고 있는 것으로 나타나, 벼 생육초기의 관개용수 염도관리는 매우 중요하다고 판단된다.

• Korean Chemical Engineering Research
• /
• v.53 no.1
• /
• pp.16-21
• /
• 2015

The body structure of diaphragm type preaction valve was improved in order to reduce the pressure drop. The pressure drop must be kept within 20.7 kPa to pass the revised (2012. 2. 9) standard for alarm valve and preaction valve. The pressure drop test was carried out by KFI (Korea Fire Institute) standard. The pressure drop of a preaction valve was higher than that of an alarm valve. Causes for increasing the pressure drop were investigated with the fluid flow in the valve. The preaction valve had more pressure drop factors (changes in velocity and direction) compared with the alarm valve. Inner structure of the preaction valve was changed to the clapper type to remove the pressure drop factors. In 80A and 100A size of preaction valves, the pressure drop was reduced from 80.9 and 171.0 kPa to 14.4 and 14.2 kPa respectively, after the change of the structure.

• Venture DIGEST
• /
• s.96
• /
• pp.8-11
• /
• 2006

국내 세무∙회계 솔루션업계의 독보적인 리더, 더존디지털웨어. 10여년 전 국내 최초로 세무조정에 대한 전산화를 이루며 업계 부동의 1위자리를 확보하고 있는 더존디지털웨어가 토털 소프트웨어기업으로 진화하기 위해 기어를 한껏 올렸다. 제2의 도약을 향한 더존디지털웨어의힘찬날개짓을유수형대표를만나들어본다.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.5
• /
• pp.503-514
• /
• 1997

The morphogenesis of panicle and spikelet in paddy rice has been studied in high yielding Indica$\times$Japonica hybrid cultivar, Milyang 23 and a Japonica type cultivar, Koshihikari. Germinated seeds planted in $5000^{-1}$ a pots filled with submerged soil and cultured under natural conditions. The young panicle of main stem were continuously dissected and observered by Cryo-SEM from the panicle initiation stage until heading stage. Although the date of panicle differentiation and heading in Koshihikari earlier than those of Milyang 23. the sequence of panicle development in two cultivars begins when first bract primordium at opposite side of flag-leaf primordium differentiated, synchronously followed by growth of the primary branch primordia (PBPs) and secondary branch primordia (SBPs), spikelet primordia(SPs), glumes as lateral organs on rachilla and organs composing single floret, and successive sporogenesis in the young spikelets continue after the enclosure by lemma and palea. The PBPs are acropetally initiated from the base of the panicle primordium, and the SBPs alternately differentiate from the base of upper PBP which differentiate later than the lower PBP. Spikelet development starts at the top of upper side PBP of the young panicle and continue basipetally even though SBPs continue to develop at the lower primary branch. Each PBP, SBP and SP differentiate with differentiation bract or bract hair cell around the base of each their primordia. The observation could confirm that Milyang 23 has not only 2~3 more defferentiated PBPs, but also more SBPs and SPs especially from middle-lower primary branch, at end of their differentiation stages, as compared to those of Koshihikari.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.6
• /
• pp.2343-2350
• /
• 2013

The wave height distributions in front of a vertically perforated wall structures for obliquely incident uni-directional irregular waves are mainly investigated by using 3D hydraulic experiments. The difference and similarity of wave propagation along the plain and perforated wall structures are investigated and particularly the effects of side walls in chamber and relative chamber width are analyzed. This study shows that the wave height distribution patterns for normalized wave heights in front of structure is significantly different between the plain and perforated wall structures, and the side wall in the chamber suppresses the growth of waves.