• 한국정밀공학회지
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• 제33권12호
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• pp.979-984
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• 2016

Recently, ball screws have been used in machine tools, robot parts, and medical instruments. The demand for ball screws of high precision and reduced size is increasing because of the growth of high value-added industries. Three types of ball screws are typically used: deflector type, end-cap type, and tube type. They are also classified from C0 to C9 according to the precision level. A deflector type ball screw can reduce the variation of rotational torque and the size of the nut of the ball screw is minimized. To ensure the reliable design of ball screws, it is important to perform a structural analysis. The purpose of this study is to perform a stability evaluation through analysis of a deflector type miniature ball screw for weapon systems. The analysis is performed through Finite Elements Method (FEM) simulation to predict characteristics such as deformation, stress, and thermal effects. The interference between the shaft and the deflector for smooth rotation are also studied. Based on the results of the analysis, the development of the deflector type miniature ball screw for weapon systems is performed.

• Journal of Chest Surgery
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• 제30권6호
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• pp.580-584
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• 1997

기존의 폐동맥 혈류 조절술(pulmonary래eV banding procedure)의 미비 점을 보완하여 피하에서 조절 가능한 폐동맥 혈류 조절기(pulmonary artery banding device)를 개발하였다. 조절기는 탄성력을 가진 스테인레스 철 사를 이용하여 지그재그형으로 형태를 만든 조절부,폴리비닐 카테터로 된 몸체 부위 및 볼트와 너트로 이 루어진 나사부로 구성되어 있다. 15∼20 kg의 네 마리 황견을 이용해 좌측 개흉술 후 하행 대동맥에 본 장 치를 장착한 후 때월 후 장치의 조절에 따르는 혈압의 변화에 대한 검사를 하였다. 검사 후 실험동물을 희생시켜 장치를 포항한 대동맥의 병리 조직 검사를 시행하였다. 조절기의 나사부를 회전시키므로서 혈관 에 장착된 조절기의 직경과 원주가 정확하고 용이하게 조절되었다. 조절기의 조절에 따라 측정한 혈압 변 화에서 혈압이 조절기의 회전수에 선형 증감을 나타냈다. 폐동맥 혈류 조절기의 장착이 용이하고 쉽게 조 절 가능하므로 이를 장차 임상에 적용시켜 보다 향상되길 기대한다.

• 소성∙가공
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• 제29권6호
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• pp.331-337
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• 2020

Blind rivet nuts (BRNs) are increasingly used in automotive industry because unlike conventional bolt fastening, BRN fastening requires access from one side only. Generally, fastening is conducted using automated units, but manual fastening may be resorted to in case of small quantities. Since the fastening direction is not exactly perpendicular to the sheet metal, the BRN axis is tilted with respect to the plate and may result in damage or incomplete fastening. As the tilt angle (clamping angle α) increases, undesired plate deformation occurs and the contact area of the plate with the BRN fastening area decreases, reducing the clamping effect. In this study, the reduction of the clamping effect with the α was investigated to ensure stable fastening force. M6 BRNs were used in the tests. The fastening force was measured as follows: the plate was cut in half through the center of the hole; the BRN was inserted into the hole and fastened; and the clamping angle a was measured (values, 0° ≤ α ≤ 9°). The force leading to the separation of the halves was measured using a universal testing machine (UTM). The maximum α range, in which the fastening force remains stable, was determined. Finite element (FE) analysis confirmed that the fastening force decreases approximately linearly with increasing α. Based on the experiment and FE analysis using various α, the fastening force was found to decrease with α. Further, the maximum tolerance for α that provides secure fastening without damage is suggested.

• 비파괴검사학회지
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• 제28권4호
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• pp.352-357
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• 2008

구조물의 안전 보장 문제에 있어 재료의 파손 이전에 미세균열을 검출하는 것은 매우 중요하다. 비선형 초음파 기법은 일반적인 초음파 기법보다 미세결함에 민감하기 때문에 이를 이용하여 비파괴적으로 구조물이나 재료의 건전성을 진단하는 방법이 주목받고 있다. 계면접촉에 의한 비선형 초음파 효과는 초음파가 내부의 미세 균열에 입사될 때 미세균열면에서 응력과 변위가 비선형 관계를 가지고, 이에 의해 파가 왜곡되어 그 결과 고조파 성분이 발생하는 현상이다. 본 연구에서는 이러한 비선형 초음파 기법의 적용가능성을 알루미늄 시편에 인위적으로 발생시킨 피로균열을 대상으로 실험적으로 검증하고자 하였다. 이를 위해 V-노치를 갖는 A16061의 피로균열 시험편을 준비하고, 균열방향으로 2차 고조파 성분의 크기를 측정하였다. 실험결과 미세균열에서 고조파 성분이 크게 발생하며 이 기법에 의한 균열깊이 측정이 일반적인 반사파의 6 dB drop법보다 정확함을 확인하였다.

• 한국유기농업학회지
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• 제19권spc호
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• pp.271-274
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• 2011

Pepper mild mosaic virus (PMMoV) and cucumber mosaic virus (CMV) are important pathogens in various vegetable crops worldwide. We have found that methanol extracts of Quercus dentate (Oaimyo Oak) gal/nut strongly inhibit PMMoV and CMV infection. Based on this result, the inhibitor named as "KN0912" formulated from the extract of Q. dentate gallnut was tested for its inhibitory effects on PMMoV or CMV infection to each local lesion host plant (Nicotiana glutinosa; PMMoV, Chenopodium amaranticolor; CMV). Pre-treatment effect of KN0912 against infections of each virus to local host plant was measured to be $75.1{\pm}0.5{\sim}97.5{\pm}1.5%$ to PMMoV and $70.6{\pm}2.2{\sim}99.0{\pm}1.0%$ to CMV in 1~10mg/ml conc. and the absorption effect of the antiviral composition of KN0912 to the inside of tobacco leaves tissue, was inhibited by 55.7% to PMMoV and 63.8% to CMV. The persistence of KN0912 treatment was maintained until after the 3 days high inhibitory effect by 98% to PMMoV and by 95.1% to CMV. Inhibitory effects on systemic host plants of KN0912 were measured to be 80~90% to PMMoV and 60~75% to CMV. From the change of morphological characteristics of PMMoV particles under EM, we are tentatively suggested that one mode of action of KN0912 is inactivation due to the destruction of virus particles.

• 한국식생활문화학회지
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• 제10권4호
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• pp.291-300
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• 1995

The purpose of this paper is to survey various recipes of the roasted beef with twenty three classical cookboods written before 1943. The roasted beefis found total 32 times in the literature which can be classified into seven groups such as the roasted rib, roasted foot, roasted tail, roasted heart, roasted gall, roasted kidney and roasted fresh meat. The most frequent one is the roasted rib appearing eight times and the next is the roasted sliced beef with seasoning appearing seven. This proves that the those recipes have been the most favorite ones to Korean people for a long time. The roasted rib has been found since the middle of the 17th century, but the process of roasting ribs again with seasoning after three successions of dipping shortly into cold water in the midst of roast wasz disappeared. The roasted sliced beef with seasoning originated since the late 18th century, and the roasted beef with salt since the early 19th century which has been inherited as the roasted raw upper part of roasted beef recipes have been continued until today in the similar manner. Generally the roasted meat with bones and the roasted internal organs started in 1766 earlier than the roasted fresh meat by a century. The main ingredients were rib, foot, tail, heart, gall, kidney, fresh meat and knee bone, and the seasonings were mixtures of scallion stalk, garlic, pepper, oil, soy sauce and sesame seed powder. And peculiarly salted shrimp, pear juice, ginger were added to seasonings and pine nut powder was used as decorating ingredient.

• 대한지역사회영양학회지
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• 제9권3호
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• pp.315-325
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• 2004

This study was conducted to develop the standard breakfast menu for those weak groups having insufficient breakfast intake. The following three target groups are classified as: 16-19 years old high school male student, 20-29 years old female who have job or college students, 20-29 years old male or female who have job (double income family). While developing menus for each target groups, we applied several basic guidelines for meal planning as follows: Nutrient intake level was set to $\graction one-Third$ of RDA, while the energy level to $\fraction one-quarter $ of RDAs. Most Sequent meal pattern of Koreans was adapted; Suitabilities of appropriate serving size and cost for middle-income families were considered; Domestic foods and ingredients were used. We developed 24 menus summed by 2 menus for each season and three target groups. When evaluating the menus, most of the breakfast menus were sufficient of nutrients as a meal for the subjects. Three food groups such as grain/starch group, meat/fish/egg/bean group, vegetable/fruit group were included in all menus. Even though milk/dairy products group was not excluded for some menus, other calcium substitutes like anchovies were used. Oil/nut/sugar group was used to a minimum. The average number of foods for each menu was 12.8, which ranged from 10 to 17 depending on the menus. The average weight of the menus including soup was 822 g, 633 g and 730 g for each target group, respectively. The average price of the menu ranged from 2,000 to 3,500 won per person. The above results could be applied at home as well as foodservice institutes and furthermore could offer information for developing breakfast-substituting food products.

• 한국식품영양과학회지
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• 제29권5호
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• pp.766-769
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• 2000

수침과정을 달리하여 제조한 도토리 앙금의 입자 특성을 조사하였다. 도토리 앙금의 X-선 회절도는 회절각도 $(2{\theta})14.5^{\circ},\;17.2^{\circ},\;19.7^{\circ},\;22.2^{\circ},\;24.5^{\circ}$에서 피크를 보이는 B형의 결정형을 보였으며, 열매의 수침과 앙금의 수침에는 영향을 받지 않았다. 또한 도토리 앙금 중 전분 입자는 대부분 타원형이며 일부는 모서리가 둥근 삼각형 모양이 존재하였고 중앙에는 hilum이 있었으며, 크기는 대부분 $10~20\;\mu\textrm{m}$ 범위였다. 열매의 앙금의 수침 과정 중 전분 입자에 붙어 있었던 비전분 성분은 대부분 제거되었다. 이상의 결과로 보아 도토리 열매와 앙금을 수침하는 기간이 입자의 성상이나 결정도에 큰 영향을 주지 않는 것으로 판단된다.

• Forest Science and Technology
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• 제14권4호
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• pp.160-168
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• 2018

The seeds of Elaeocarpus serratus, a tropical underutilized fruit tree are characterized by hard seed coat and consequent poor water uptake and low germination. To improve the regeneration through seeds, various parameters such as viability of seeds, water uptake, and effect of seed mass on germination and pretreatments were performed using a completely randomized design (CRD). Tetrazolium (TZ) test was conducted using fresh, mature seeds revealed $50{\pm}2.56%$ mean viability. Seeds of different weight classes showed similar pattern of water uptake and the saturation level was achieved at 60 hrs of soaking. Seeds belong to weight class 2.6-3.5g were germinated ($12.5{\pm}1.26%$) with $175{\pm}1.75days$ (d) of mean time taken for germination (MTG). Germination capacity of seeds varied significantly among different populations and Varkala population gave $12.5{\pm}1.1%$ germination with $174.6{\pm}2.5d$ MTG. Among various seed treatments, mechanical scarification was superior in germination and significant reduction in MTG ($p{\leq}0.05$). The mechanical scarification by complete removal of seed coat resulted in $49.2{\pm}1.52%$ germination within a short period of time ($9.52{\pm}0.89d$ MTG). However, the complete removal of seed coat without damaging to embryo is a difficult task. An alternate treatment (Mechanical scarification II) by making cracks on nut faces vertically followed by soaking in distilled water for 24 hrs gave $48.4{\pm}1.73%$ germination with significantly reduced MTG ($12.14{\pm}0.56d$) over unsoaked, untreated control ($6.5{\pm}1.84%$ germination and $197.18{\pm}1.79d$ MTG; $p{\leq}0.05$). This treatment (Mechanical scarification II) is therefore recommended for E. serratus seeds as it can adopt easily and can achieve 7 fold increases in germination over control. The recorded germination through mechanical scarification is in tune with realized viability percentage of the seeds.

• 소성∙가공
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• 제31권6호
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• pp.376-383
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• 2022

The potential damage region of a WC-Co cemented carbide die is investigated for cold forging process of a wheel-nut by numerical simulation with its chemical composition considered. Numerical simulation is utilized to calculate internal stress, especially for the WC-Co die, during the forging process. Finite element model is established, in which the elasto-plastic properties are applied to the work-piece of bulk steel, and elastic properties are considered for the lower die insert of the WC-Co alloy. This stress analysis enables to distinguish the potential damage regions of the WC-Co die. The regions from calculation are comparatively analyzed along with the crack area observed in the die after repetitive manufacturing. Effect of chemical composition of the WC-Co is also evaluated on characteristics of potential damage region of the die with variance of mechanical properties considered. Derived from Mohr-Coulomb fracture model, furthermore, a new stress index is presented and used for die stress analysis. This index inherently considers hydrostatic pressure and is then capable of deducing wide range of its distribution for representing stress state by modification of its parameter implying pressure sensitivity.