• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.271-272
• /
• 2009

In this study, the application results of high volume fly ash concrete(HVFAC) on the construction site were reported. The structures were the mat foundations of 3m and 2m thickness with design strength of 40MPa. The replacement ratio of fly ash was 50%, and the pre-mix type binder was used. As a result, it appeared that the temperature increases of concrete foundations were about $39^{\circ}$C for 3m thickness and $36^{\circ}$C for 2m thickness.

• Communications of the Korean Mathematical Society
• /
• v.19 no.2
• /
• pp.233-242
• /
• 2004

The aim of this note is to study properties of the generalized centroid of the semi-prime gamma rings. Main results are the following theorems: (1) Let M be a semi-prime $\Gamma$-ring and Q a quotient $\Gamma$-ring of M. If W is a non-zero submodule of the right (left) M-module Q, then $W\Gamma$W $\neq 0. Furthermore Q is a semi-prime $\Gamma$-ring. (2) Let M be a semi-prime $\Gamma$-ring and $C_{{Gamma}$ the generalized centroid of M. Then $C_{\Gamma}$ is a regular $\Gamma$-ring. (3) Let M be a semi-prime $\Gamma$-ring and $C_{\gamma}$ the extended centroid of M. If $C_{\gamma}$ is a $\Gamma$-field, then the $\Gamma$-ring M is a prime $\Gamma$-ring.

• Communications of the Korean Mathematical Society
• /
• v.38 no.1
• /
• pp.223-234
• /
• 2023

The main purpose of this paper is to study the lightlike hypersurface (M, $\overline{g}$) of cosymplectic space form $\overline{M}$(c). In this paper, we computed the Gauss and Codazzi formulae of (M, $\overline{g}$) of cosymplectic manifold ($\overline{M}$, g). We showed that we can't obtain screen semi-invariant lightlike hypersurface (SCI-LH) of $\overline{M}$(c) with parallel second fundamental form h, parallel screen distribution and c ≠ 0. We showed that if second fundamental form h and local second fundamental form B are parallel, then (M, $\overline{g}$) is totally geodesic. Finally we showed that if (M, $\overline{g}$) is umbilical, then cosymplectic manifold ($\overline{M}$, g) is flat.

• Journal of Aquaculture
• /
• v.13 no.2
• /
• pp.119-128
• /
• 2000

Exposure to air and increased temperature induced successful spawning in Mytilus edulis, M. coruscus Crassostrea gigas and Pinctata fucata martensii. Developmental durations required for an egg to attain D-shaped larva and the D-shaped larva to reach pediveliger stage were estimated in these bivalves. Size of fertilized eggs was the largest (70.3 ${\mu}m$) in M. coruscus and the smallest (45.3 ${\mu}m$) in P. fucata martensii. At 17$^{\circ}C$, M. edulis and M. coruscus attained D-shaped larval stage within 48 hours after fertilization but those of C. gigas and B. fucata martensiii within 24 and 22 hours at 21 and 26$^{\circ}C$, respectively. The development duration required for a D-shaped larva to attain pediveliger stage was the longest (27 days) in M. coruscus and ranged between 20 and 22 days for the others. The shell length of the pediveliger was the longest (274.9 ${\mu}m$) in C. gigas and smallest (190.9 ${\mu}m$) in P. fucata martensii Length and height of larval shell was highly correlated with each other in all the 4 species. The shell height of C. gigas was more than the shell length beyond the size of 100 ${\mu}m$ shell length. However, shell length of the others was always longer than shell height at the larval stage.

• Honam Mathematical Journal
• /
• v.42 no.2
• /
• pp.235-249
• /
• 2020

Let Q and R be the well-known matrices associated with Fibonacci and Lucas numbers, and k, m, and n be any integers. It is mainly established all solutions of the matrix equations c₁Qⁿ + c₂Q^m = Q^k, c₁Qⁿ + c₂Q^m = RQ^k, and c₁Qⁿ + c₂RQ^m = Q^k with unknowns c₁, c₂ ∈ ℂ*. Moreover, using the obtained results, it is presented many identities, some of them are available in the literature, and the others are new, related to the Fibonacci and Lucas numbers.

• Journal of Chest Surgery
• /
• v.26 no.8
• /
• pp.650-653
• /
• 1993

Congenital cystic adenomatoid malformation [ C.C.A.M.] is rare, but often fatal congenital lung bud anomaly that causes acute respiratory distress in the newborn infants. In those who survive infancy and early childhood, its clinical manifestations are not unusual to detect. Recently we experienced an infant with C.C.A.M. Type II. The patient was a 7-month-old male, and had been suffering from coughing and fever since 3 months ago. The symptom were not improved with medical treatment and then, exploratory thoracotomy was performed under the impression of infected C.C.A.M. or other congenital cystic disease.The left lower lobectomy was performed, and the postoperative course was uneventful.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.5 no.3
• /
• pp.1-6
• /
• 2003

The purpose of this study was to investigate the dyeability and color fastness of cotton and silk fabrics dyed with extract of Arrowroot leaf princeps. The experimental items were divided into the mordant treatment, component of fabric and kind of mordants. The experimental study was done by laundering, abrasion(dry/wet), perspiration(acid/alkali), light fastness, color difference by C.C.M system and K/S test. The summerized finding reulted from experiment and investigation are suggested as follows : In the C.C.M and K/S test on mordanting method and kind of fabric, that of silk and cotton was the most effective in the pre mordant treatment. In the C.C.M and K/S analysis on 5 mordants, that of silk and cotton was significantly improved when mordants was treatmented. Especially, that of Fe mordanting treatment was higher than Al, Cu, Cr and none. In color fastness on mordants, laundering, perspiration and abrasion fastness showed 4-5 grade but light fastness showed 1-3 grade.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.05a
• /
• pp.919-924
• /
• 1995

사람이 숨을 쉬는 동안에 대기중에 포함된 C-14이 인체내에 흡수되는 경로를 살펴보았으며 이로부터 호흡경로를 통한 C-14의 체내 흡수량을 평가하였는데, 호흡중 C-14이 체내에 흡수되는 속도는 다음과 같이 구해졌다. $Q_{i}$(mBq/min)=7.250C$_{a.in}$ - 0.87 여기서 $C_{a,in}$ 은 공기중에 포함된 이산화탄소중의 C-14 농도(mBq/$m\ell$$CO_2$)이다. 이를 토대로 백그라운드 준위보다 약 10,000배 높은 작업환경(400 Bq/$m^2$)에서 8시간 동안 방사선작업을 수행하였을 경우 방사선 작업자는 일반인에 비해 약 4,100 Bq의 C-14 방사능을 추가로 섭취하게 되고, 이로 인해 작업자가 받게 될 체내 피폭선량은 약 0.06 mrem이었다.

• Journal of the Korean Ceramic Society
• /
• v.40 no.1
• /
• pp.18-23
• /
• 2003

Composite powder of$B_4C-A1_2O_3$was prepared from a mixed powder of$B_2O_3/A1/C$by SHS under argon pressure instead of using a chemical furnace. A mixture of$B_2O_3,$Al and C powder (equivalent amounts to the reaction,$2B_2O_3+4A1+C=B_4C+2A1_2O_3)$was ball milled for 2 h. The mixed powder was placed in a SHS reactor and filled with 10 atm of argon gas and ignited. The inner and outer products were the same by XRD analysis. It was consisted of a composite powder of$B_4C-A1_2O_3$without $AlB_{12}/C_2$which was always produced using a chemical furnace. The composite powder was about$60~100{mu}m$size which was composed of crystalline particles of about 0.3~l${mu}m$size. But when 15 atm of argon was employed, partial sintering took place to give rise hard composite powder of$15~25{mu}m$$B_4C$with $0.1~0.2{mu}m$$A1_2O_3.$

• Journal of applied mathematics & informatics
• /
• v.30 no.3_4
• /
• pp.531-540
• /
• 2012

An approximation for the number of customers at service facility in $M/G/c/K$ retrial queue is provided with the help of the approximations of ordinary $M/G/c/K$ loss system and ordinary $M/G/c$ queue. The interpolation between two ordinary systems is used for the approximation.