• Bulletin of the Korean Mathematical Society
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• v.61 no.1
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• pp.45-64
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• 2024

Let G be a finite group, K a split field for G, and L a linear map from K[G] to K. In our paper, we first give sufficient and necessary conditions for Ker L and Ker L ∩ Z(K[G]), respectively, to be Mathieu-Zhao spaces for some linear maps L. Then we give equivalent conditions for Ker L to be Mathieu-Zhao spaces of K[G] in term of the degrees of irreducible representations of G over K if G is a finite Abelian group or G has a normal Sylow p-subgroup H and L are class functions of G/H. In particular, we classify all Mathieu-Zhao spaces of the finite Abelian group algebras if K is a split field for G.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.2
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• pp.225-234
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• 2009

The aim of this study was to analyze moisture, crude protein, crude lipid, vitamin C and sugar changes in selected Korean chestnut cultivars such as Danteack, Deabo, Seokchu, Okkwang and Byunggo during storage at $4^{\circ}C$ and $-10^{\circ}C$ for 10 months. The moisture contents of selected Korean chestnut cultivars ranged from 49.9 to 57.4%. The moisture content of Seokchu was the highest. The contents of moisture in white kernel were higher than that in yellow kernel. The content of moisture showed decreasing tendency after 10 months of storage. The crude protein and crude lipid contents in whole kernel of selected Korean chestnut cultivars were $3.3{\sim}4.2%$ and $0.3{\sim}1.6%$, respectively. The crude protein content of Deabo was the highest. The crude protein in Danteack, Seokchu, Okkwang and Byunggo was increased during storage at $4^{\circ}C$ for 10 months, while that in whole kernel of Deabo was decreased and no changes in crude protein in yellow kernels of Deabo were observed. The crude protein in Okkwang was increased during storage at $-10^{\circ}C$ for 10 months. The cold storage was found to have higher composition change of crude protein than the freezing storage. The content of crude lipid in Daebo and Byunggo was decreased during storage at $4^{\circ}C$ and $-10^{\circ}C$. Yellow kernels of Deabo, Okkwang and Byunggo were found to have higher crude lipid content than white kernels. The vitamin C content also decreased during storage at $4^{\circ}C$ and $-10^{\circ}C$ and the decrease in vitamin C content was higher at $4^{\circ}C$ than $-10^{\circ}C$. Vitamin C was not detected after 3 months storage at $-10^{\circ}C$. The sugar content increased at the latter period storage at $4^{\circ}C$ and $-10^{\circ}C$. The sugar content of selected Korean chestnut cultivars ranged from $36.2{\sim}44.3%$ and Dantaek had the highest sugar content.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.399-405
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• 2016

The objective of this study was to determine the effect of sakso 2 corn kernels and cobs extracts on antioxidant activity in rats fed a high fat-cholesterol diet (HFC) for 2 weeks. 48 male Sprague-Dawley (4-weeks-old) were randomly divided into 6 groups: normal diet (N), HFC (C), HFC and 0.05% kernel extracts of Saekso 2 (T1), HFC and 0.25% kernel extracts of Saekso 2 (T2), HFC and 0.05% cob extracts of Saekso 2 (T3), HFC and 0.25% cob extracts of Saekso 2 (T4). The weight gain in all treatment groups were significantly lower and the food efficiency ratio (FER) in all treatment groups except T3 were lower than C group. Liver index (liver weight/100 g body weight) in N group and T2 were significantly lower than C group. The level of total cholesterol in plasma of N group and T2 were significantly lower than C group and HDL-cholesterol in plasma of N group and T2 were significantly lower than C group. Malondialdehyde (MDA) concentration of thiobarbituric acid reactive substances in N group, T3 and T4 were significantly lower than C group. Activity of catalase (CAT) in all treatment groups were lower than C group. These result suggest that saekso 2 corn kernels and cobs extracts may reduce oxidative damage through the activation of antioxidative defense systems in rats fed high fat-cholesterol diets.

• Journal of the Korean Society of Radiology
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• v.83 no.3
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• pp.669-679
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• 2022

Purpose To evaluate the feasibility of pediatric low-dose facial CT reconstructed with filtered back projection (FBP) using adequate kernels. Materials and Methods We retrospectively reviewed the clinical and imaging data of children aged < 10 years who underwent facial CT at our emergency department. The patients were divided into two groups: low-dose CT (LDCT; Group A, n = 73) with a fixed 80-kVp tube potential and automatic tube current modulation (ATCM) and standard-dose CT (SDCT; Group B, n = 40) with a fixed 120-kVp tube potential and ATCM. All images were reconstructed with FBP using bone and soft tissue kernels in Group A and only bone kernel in Group B. The groups were compared in terms of image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Two radiologists subjectively scored the overall image quality of bony and soft tissue structures. The CT dose index volume and dose-length product were recorded. Results Image noise was higher in Group A than in Group B in bone kernel images (p < 0.001). Group A using a soft tissue kernel showed the highest SNR and CNR for all soft tissue structures (all p < 0.001). In the qualitative analysis of bony structures, Group A scores were found to be similar to or higher than Group B scores on comparing bone kernel images. In the qualitative analysis of soft tissue structures, there was no significant difference between Group A using a soft tissue kernel and Group B using a bone kernel with a soft tissue window setting (p > 0.05). Group A showed a 76.9% reduction in radiation dose compared to Group B (3.2 ± 0.2 mGy vs. 13.9 ± 1.5 mGy; p < 0.001). Conclusion The addition of a soft tissue kernel image to conventional CT reconstructed with FBP enables the use of pediatric low-dose facial CT protocol while maintaining image quality.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.392-401
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• 2023

Corn (Zea mays L.) is one of the world's most important crops, along with wheat and rice, with a global corn production expected to reach 1,154.5 million tons in 2023. Considering this grain production, The generation of corn cob is expected to reach approximately 207.8 million tons in 2023. However, as an agricultural by-product, corn cobs are often considered waste and remain underutilized. Phytosterols, which are abundant in vegetable oils such as corn oil, provide a number of health benefits, including liver health, cholesterol reduction, and protection against chronic diseases such as diabetes. In this study, we investigated the potential of Kwangpyeongok ears, which are commonly used as grain and silage corn in Korea. We also examined the variation in phytosterol content with the maturity of corn ears to identify the optimal time for utilization. At the beginning of physiological maturity, corn cobs had 113.3 mg/100g DW of total phytosterols, which was highest phytosterol abundance during the growth stage. Corn kernels also had the highest phytosterol content at the beginning of physiological maturity. While previous studies on corn bioactive compounds have mainly focused on the kernels, the results of this study highlight that cobs are an excellent source of these compounds. Furthermore, phytosterol levels were influenced by genetic factors and developmental stages, suggesting the to increase the use of cobs as a source of bioactive compounds.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1254-1264
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• 2008

This paper suggests an extended memory polynomial model that improves accuracy in modeling memory effects of RF power amplifiers(PAs), and verifies effectiveness of the suggested method. The extended memory polynomial model includes cross-terms that are products of input terms that have different delay values to improve the limited accuracy of basic memory polynomial model that includes the diagonal terms of Volterra kernels. The complexity of the memoryless model, memory polynomial model, and the suggested model are compared. The extended memory polynomial model is represented with a matrix equation, and the Volterra kernels are extracted using least square method. In addition, the structure of digital predistorter and digital signal processing(DSP) algorithm based on the suggested model and indirect learning method are proposed to implement a digital predistortion linearization. To verify the suggested model, the predicted output of the model is compared with the measured output for a 10W GaN HEMT RF PA and 30 W LDMOS RF PA using 2.3 GHz WiBro input signal, and adjacent-channel power ratio(ACPR) performance with the proposed digital predistortion is measured. The proposed model increases model accuracy for the PAs, and improves the linearization performance by reducing ACPR.

• Food Science and Preservation
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• v.9 no.3
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• pp.267-270
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• 2002

This study was carried out to establish storage methods and to keep high quality of the raw and boiled vegetable peanut. After boiling at 100$^{\circ}C$ for 20min at 7% saline water far 40min the pods were packaged with 80 $\mu\textrm{m}$ Ny/LDPE film in vacuum, 80$\mu\textrm{m}$ LDPE film and Gauge-bag, and stored at room temperature and 4$^{\circ}C$. The moisture content of pods in room temperature were decreased than pods at 4$^{\circ}C$. After 21days storaging with Gauge-bag, texture of pods were toughen because moisture content of pods reduced severely. Colour of raw pods in packaging 80 $\mu\textrm{m}$ Ny/LDPE film vacuum was severely browning but boiled pods was browning little after opening a seal. After 2days storage at room temperature and 21days storage at 4t, pods were deteriorated. The hardness was much lower in boiled kernels than raw kernels and decreased when the storage period elapsed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.36-44
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• 2007

In order to evaluate the utilization of immature green barley kernels as food processing material, these experiments were carried out to analyze free sugars, free amino acids, mineral contents and color of two naked barley varieties according to their heading dates. Contents such as moisture, protein, fat, ash, and free sugars were gradually decreased according to the days after heading of the nonwaxy naked barley 'Saessalbori' and waxy naked barley 'Hinchalssalbori', while crude fiber and starch were gradually increased. Contents like maltose and maltotriose in immature green kernels were high, but free amino acids showed a tendency to decrease, among which the alanine content was the highest. As barley matured, beta-glucan content, redness and yellowness increased, while lightness decreased. Considering chemical composition and color, the immature green cereals were produced through blanching the spikes harvested before the yellow ripe stage around $26{\sim}27$ days after heading. The optimum duration of harvest was very limited to produce green whole grains. The harvested green barley cereals is able to eat raw barley or cook it as food processing material.

• Korean Journal of Food Science and Technology
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• v.17 no.1
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• pp.25-32
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• 1985

Low-temperature in-bin paddy drying has been examined to study the limitations of this drying method under Korean weather conditions, the initial moisture content of the paddy, the bulk depth and the airflow rate. The results are reported and discussed with regard to drying time, energy requirements and costs, uniformity in the moisture content of the dried kernels and, finally, the quality of the paddy. The tests carried out during the paddy-drying period in 1981 and 1982 have shown that under Korean weather conditions paddy can be dried to safe storage conditions by continuous aeration with ambient air. Depending upon the initial moisture content of the kernels(19.2%-25.5% w.b.), the bulk depth(1.1-3.5m) and the airflow $(3.0-6.9m^3\;air/m^3\;paddy/min)$ the paddy could be dried within 5 to 17 days. The energy requirements and energy costs are shown to be considerably lower than for conventional high-temperature drying. No significant changes in the quality in terms of milling yield, cracking ratio, acid value and germination were observed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.2
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• pp.166-176
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• 2009

Eighteen Korean chestnut cultivars were collected from various places and the proximate compositions, dietary fiber, amino acid and free sugar contents in three parts (whole kernel, white kernel, yellow kernel) of eighteen Korean chestnut cultivars were analyzed. The white kernel of Chukfa and the yellow kernel of Ipyung contained the highest amount of moisture and crude protein, respectively. Carbohydrate content of whole kernel showed a range of $30.8{\sim}52.0%$ and crude ash content of whole kernel showed a range of $0.9{\sim}1.8%$. The amount of crude lipid was the highest in Byunggo. The amount of dietary fiber in Kwangeun, Daebo, Parkmi 1 ho, Yooma and Pyeonggi were higher than that of other Korean chestnut cultivars. Seventeen amino acids were detected. Major amino acids of the various chestnuts were aspartic acid and leucine. The amount of amino acids was higher in Ichui, Ipyung and Pyeonggi but was lower in Dantaek and Sandae than that of other samples. The major free sugar in the chestnuts was glucose. The free sugar amount of yellow kernels was higher than the white kernels.