• Korean Journal of Plant Taxonomy
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• v.41 no.1
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• pp.58-65
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• 2011

Commelina benghalensis L. and Commelina diffusa Burm. f. belonging to Commelinaceae, two species previously unrecorded as Korean flora, were collected in the lowlands of Jeju Island in Korea. Commelina benghalensis of the two species is different from others of Commelinaceae in Korea by having funnelform spathes fused at the proximal margin of involucral bracts and cleistogamous flowers. In addition, Commelina diffusa differ from others by having a three-valve capsule and lanceolate and a base cordate or rounded spathelike involucral bracts. The somatic chromosome number of Commelina benghalensis was 2n = 2x = 22 and the sizes of chromosomes were very small, ranging from 1.25 to 2.70 ${\mu}m$. However, the Commelina diffusa chromosome number exceeded 2n = ca. 100, and a precise count could not be obtained. These species are known to be distributed in tropical and subtropical regions of Asia and Africa below the latitude of Jeju Island of Korea.

• Animal Systematics, Evolution and Diversity
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• v.11 no.3
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• pp.359-377
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• 1995

Morphological and isozyme analyses were used to examine closely related species of Tridentiger obscurus and \ulcorner: brevispinis, a pair of cryptic species which has intricate problem with regard to species boundary, and to clarify the taxonomic position. In this study, it was revealed from their 17 allopatric streams that there are differences of band ornamentation on the lateral side and three genetic markers between two species. However, genetic relationship between them (S = 0.813, D = 0.192) was within the intraspecific level of similarity. However, at the sympatry of two species no hybrid was found except at Bangjuk stream where the electrophoretic hybrids with slight deficiency of heterozygosity were observed. It is shown that at sympatry there is a finer microenvironmental subdivision between two species at all populations including Bangjuk stream. To manifest the extent of assortative mating, four syrnpatric subpopulations at Bangjuk stream were analyzed for departure from Hardy-Weinberg equillibrium by F-statistics. All subpopulations were deviated significantly from the expectation under random mating. The evidences presented here supports the recognition of Tridentiger obscurus and T. brevispinis as semispecies in the late stage of reproductive isolation

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.92-97
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• 2005

A series of combustion test was done to verify the optimization result of a gas generator for a 10 ton thrust liquid rocket engine. An injector element is F-O-F impinging type injector and the test was conducted with kerosene/LOX propellants. Test results of combustion temperature and pressure show a very good agreement with optimal design result and verify that the design method was properly established. And turbulence ring revealed its effectiveness in enhancing combustion gas mixing and temperature difference in the radial direction showed only less than 15K. Also turbulence ring induced only 3.2% pressure loss in the combustion chamber, which is far less than conventional level observed in a gas turbine engine. Axial temperature distribution also shows that turbulence ring could effectively reduce about 10% or more in gas generator length if its location is properly selected.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6C
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• pp.321-329
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• 2009

Laboratory compressive test was conducted on 6 different types of rock in order to investigate the characteristic of critical strain under uniaxial and triaxial stress condition. The results of uniaxial compressive test mostly ranged within 1~100MPa, the critical strain was also located between 0.1~1.0%. Therefore the results distributed within the upper and lower boundary proposed by Sakurai (1982). And the failure/critical strain ratio (${\varepsilon}_f/{\varepsilon}_0$) showed between 1.0~1.8 value depending on the uniaxial compressive strength. The results of critical strain by triaxial compressive test showed below 0.8% value for all test, the M value calculated from uniaxial and triaxial compressive test results ranged 1.0~8.0 for most of rock specimens. It is concluded that failure strain (${\varepsilon}_{f3}$) of rock mass, which is in triaxial stress condition is larger than the results of uniaxial stress condition (${\varepsilon}_{f1}$) by 1.0~8.0 times and value showed 1.0~1.8 larger value than critical strain (${\varepsilon}_{01}$). Therefore it is a conservative way for rock tunnel to use critical strain (${\varepsilon}_{01}$) calculated from a uniaxial compressive strength on tunnel displacement monitoring.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.219-228
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• 2004

Confidence interval estimators for proportions using normal approximation have been commonly used for coverage analysis of simulation output even though alternative approximate estimators of confidence intervals for proportions were proposed. This is -because the normal approximation was easier to use in practice than the other approximate estimators. Computing technology has no problem with dealing these alternative estimators. Recently, one of the approximation methods for coverage analysis which is based on arcsin transformation has been used for estimating proportion and for controlling the required precision in [12]. In this paper, we compare three approximate interval estimators, based on a normal distribution approximation, an arcsin transformation and an F-distribution approximation, of a single proportion. Three estimators were applied to sequential coverage analysis of steady-state means, in simulations of the M/M/1/$\infty$ and W/D/l/$\infty$ queueing systems on a single processor and multiple processors.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.179-181
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• 2023

본 논문에서는 GAN 기반의 영상 생성 방법론을 이용해 delayed PET 영상을 생성하는 연구를 수행하였다. PET은 양전자를 방출하는 방사성 동위원소를 표지한 방사성의약품의 체내 분포를 시각화함으로서 암 세포 진단에 이용되는 의료영상 기법이다. 하지만 PET의 스캔 과정에서 방사성의약품이 체내에 분포하는 데에 걸리는 시간이 오래 걸린다는 문제점이 존재한다. 따라서 본 연구에서는 방사성의약품이 충분히 분포되지 않은 상태에서 얻은 PET 영상을 통해 목표로 하는 충분히 시간이 지난 후에 얻은 PET 영상을 생성하는 모델을 GAN (generative adversarial network)에 기반한 image-to-image translation(I2I)를 통해 수행했다. 특히, 생성 전후의 영상 간의 영상 쌍을 고려한 paired I2I인 Pix2pix와 이를 고려하지 않은 unpaired I2I인 CycleGAN 두 가지의 방법론을 비교하였다. 연구 결과, Pix2pix에 기반해 생성한 delayed PET 영상이 CycleGAN을 통해 생성한 영상에 비해 영상 품질이 좋음을 확인했으며, 또한 실제 획득한 ground-truth delayed PET 영상과의 유사도 또한 더 높음을 확인할 수 있었다. 결과적으로, 딥러닝에 기반해 early PET을 통해 delayed PET을 생성할 수 있었으며, paired I2I를 적용할 경우 보다 높은 성능을 기대할 수 있었다. 이를 통해 PET 영상 획득 과정에서 방사성의약품의 체내 분포에 소요되는 시간을 딥러닝 모델을 통해 줄여 PET 이미징 과정의 시간적 비용을 절감하는 데에 크게 기여할 수 있을 것으로 기대된다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.485-495
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• 1991

This experiment was carried out to obtain the information on the crossability, variation of chromosome number in pollen mother cell (PMC) and somatic cell of the progeny from the cross between hexaploid triticale cv. Sinkihomil and two diploid rye varieties. Seed set was 39.3 to 41.6% (averaged 40.5%) in the cross between triticale (P$_1$) and rye(P$_2$), which resulted in 0.33% in F$_2$(selfed F$_1$), 2.69% in F$_1$/P$_1$ 5.47% in F$_1$/P$_2$ respectively. However, seed set was extremely low in both reciprocal crosses when triticale was used as male. Germination rate of the crossed seed was 94.0% in F$_1$ 40.8% in F$_2$(selfed F$_1$), 59.5% in F$_1$/P$_1$ and 65.9% in F$_1$/P$_2$ from the cross between triticale and rye, respectively. Pollen fertility of F$_1$ plant was averaged 18.7% in the cross between triticale and rye. Number of Uni-, Bi-, and Trivalent in PMC was 12. 6, 6.94, and 0.53, respectively, in the F$_1$ between the triticale and rye. There were 28 chromosomes in F$_1$, 21 to 34 in F$_2$, 34 to 38 in F$_1$/P$_1$ and 19 to 23 in F$_1$/P$_2$ from the cross between the triticale and rye, respectively.

• Journal of Sericultural and Entomological Science
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• v.31 no.1
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• pp.25-36
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• 1989

In this experiment, gene action were analyzed for seven silkworm varieties in order to obtain basic information on their genetic improvement by diallel crosses. The results obtained were summarized as follows : In F1 generation, over-dominance was shown by Vr-Wr graphic analysis in four characters such as cocoon length in female, bave weight, cocoon weight and boiling off ratio in both male and female, and partial dominance in four characters such as fifth instar period, cocoon layer weight, cocoon layer ratio and bave length. In F2 generation, the partial dominance in all characters were obtained. Components of genetic variance analyzed for five characters such as fifth instar period, cocoon width, cocoon layer weight, cocoon layer ratio and fibroin contents in F1 generation, and for four characters such as cocoon width, cocoon layer weight, cocoon layer ratio and frbroin contents in F2 generation showed that addition effects were higher than dominant effects.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.331-337
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• 1994

In order to develop a $^{18}F$-labelled myocardial perfusion agent(flow tracer) for PET, $^{18}F$-labelled organic ammonium cations were synthesized and evaluated in relation to their biodistribution. Five quaternary organic ammonium compounds were labelled with $^{18}F$ in a side chain with moderate to good yields by direct introduction of $^{18}F$-fluoride. Radiochemical yields have been achieved in 30-40min by the precursors (tosylates) in dimethylsulfoxide 15-60% (decay corrected). The reaction was found to be autocatalyzed. A remote controlled procedure was developed in these synthesis. $^{18}F$-Labelling and HPLC-purification of com-pounds needed about 60 min(Yield; 7-20%). Up to now the two compounds N-4-[$^{18}F$]fluorobutyl-pyridinium cation(1) and N, N dibenzyl-4(2-[$^{18}F$]fluoroethyl)piperidinium cation(2) were investigated in relation to their biodistribution in mice. Compound 1 showed at 1 min post injection the high uptake of 19.22% ID/g organ in the myocardium but a following fast decline to 1.12% ID/g organ after 40min. Uptake of compound 2 was after 1min in the heart 5.90% ID/g organ but after 40min at the relative high value of 4.33% ID/g organ. Heart:blood ratio for compound(1) at 1 min was 8.3, at 40 min 2.6 for compound II 2.0(1min) and 15.0(40 min). As data of compound 2 showed greater heart uptake, slower myocardial release, and higher heart: blood ratios, compound 2 is a good candidate for further evaluation.

• Korean Journal of Materials Research
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• v.1 no.4
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• pp.214-220
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• 1991

The effects of $SiO_2$ reactive ion etching (RIE) in $CHF_{3/}C_2F_6$ on the surface properties of the underlying Si substrate were studied by X-ray photoelectron spectroscopy(XPS) and secondary ion mass spectrometry(SIMS) techniques. Angle-resolved XPS analysis was carried out as non-destructive depth profile one for investigating the chemical bonding states of silicion, carbon, oxygen and fluorine. The residue layer consists of C-F polymer. O-F bond was found on the top of the polymer layer and Si-O, Si-C and Si-F bonds were detected between Si substrate and polymer film. A 60nm thick damaged layer of silicon surface mainly contains carbon and fluorine.