본 연구는 2019년부터 2021년 9월까지 수집된 홀스타인 젖소 19,930두의 자료를 수집하였으며, 3 SD (Standard Deviation, SD) 범위에서 벗어나는 이상치를 제외한, 8,675두를 분석에 이용하였다. 자료분석은 Statistical Analysis System (SAS) 9.4 software를 사용하였고, 뒷유방높이, 뒷유방너비, 유방깊이, 유두길이 및 유두둘레의 실측치를 사용하였다. 그리고 뒷유방높이, 뒷유방너비, 유방깊이, 유두길이 및 유두둘레의 실측치와 산차, 305일 유량, 비유단계 및 착유속도의 환경요인의 효과를 추정하였다. 산차와 유량이 증가함에 따라 뒷유방너비, 유두길이 및 유두둘레의 실측치는 유의적으로 증가하는 것으로 나타났으며(p < 0.0001), 비유단계에 따라서 뒷유방너비 및 유방깊이의 실측치는 비유단계가 증가할수록 유의적으로 감소하는 것으로 나타났다(p < 0.0001). 각 환경효과에 따른 유방형질 실측치의 표현형 상관의 결과에서는 뒷유방너비와 유방깊이 실측치가 산차 및 유량수준에 대해 높은 상관을 나타냈으며, 특히, 유방형질 중 유방깊이 실측치와 산차에 대해 -0.40 ~ -0.67로 높은 음(-)의 상관을 보였다. 본 연구 결과로 미루어 볼 때, 유방형질이 유생산에 밀접한 관련이 있는 만큼 중요한 형질로 취급되어야 하며, 이들의 기초연구와 함께 유전적 특성을 구명하는 등 더 많은 연구가 수행되어야 할 것으로 사료된다.

The present experiment was designed to investigate the effects of extruded linseed supplementation on methane production in Holstein steers. Four Holstein steers fitted with permanent cannulas were assigned to two dietary treatments in a duplicated 2 × 2 Latin square design: a control diet consisting of tall fescue straw (65%) and concentrate (35%), and a treatment diet supplemented with 3.8% extruded linseed by replacing a part of ingredients in the concentrate of the control diet. The concentrates of the control and the treatment diet were isoenergetic and isonitrogenous. Extruded linseed supplementation did not affect dry matter intake but significantly (P<0.05) increased the intake of lipid. Rumen pH was significantly (P<0.05) lower for control than for treatment. Although there was no significant difference between treatments, the concentration of total VFA in control was 21% higher than in treatment. The concentrations of acetic acid, propionic acid and butyric acid were not different between treatments. Extruded linseed supplementation significantly (P<0.05) reduced methane output(g/d) and emission factor. Methane conversion rate was lower for treatment than for control but no significant difference was found. The results of the present study showed that extruded linseed supplementation in the diet of Holstein steers could reduce methane output.

Mobile games’ proportion in domestic game industry has been rising steadily every year and in next couple of years, it is likely to surpass online games. Considering that mobile games’ lifespan is very short compared to online games, recognizing the user’s needs at the beginning is important. However, there is a lack of research in such game field. This research is about mobile games’ initial experience importance in temporal viewpoint. Furthermore, it has verified whether this depends on user’s characteristic. I have conducted observation experiment on users of ‘Lineage M’, mobile MMORPG game, for one week starting from the game launch and deducted the importance of initial experience using AHP analysis. Moreover, by analyzing the differences in users’ proficiency, the research provides understanding of diverse users. In conclusion, this research provides basic data for improving satisfaction of initial game users and extending them to long-term game use.

본 연구는 운전자 연령대와 뇌손상 여부에 따라 다양한 반응시간 과제에서의 반응시간과 반응정확성에서 어떠한 차별성이 있는지 살펴볼 목적으로 수행되었다. 이를 위해 30-50대의 중년운전자, 65세 고령운전자, 그리고 65세 이상의 뇌졸중 고령운전자들을 대상으로 단순반응, 2-선택반응, 자극 이심률을 달리한 4-선택반응, 탐색반응 및 동적자극 탐지 과제에 대한 수행을 비교하였다. 본 연구의 결과를 정리하면 다음과 같다. 첫째, 전반적으로 중년, 고령 및 뇌졸중 고령운전자 순으로 느린 반응시간을 보였으나 자극 이심률이 작은 조건(5o)에 비해 큰 조건(10o)에서 뇌졸중 고령운전자의 반응시간이 다른 집단에 비해 더 두드러지게 지연되었다. 둘째, 전체 반응시간에서 단순 반응시간을 감산한 반응시간 을 분석한 결과, 2-선택반응 과제와 동적자극 탐지과제에서의 집단간 반응시간 차이는 유의하지 않았는데, 이것은 이러한 과제들에서의 반응시간 차이가 단순 반응시간에 의해 주로 결정된다는 것을 시사한다. 셋째, 일시적 기억을 요구하는 탐색과제에서는 두 고령운전자 집단이 중년운전자 집단에 비해 유의하게 느리고 부정확한 수행을 보였다. 넷째, 집단간 반응정확성에서의 차이는 선택 대안이 많은 과제와 기억을 요구하는 과제에서 두드러졌다. 이러한 결과는 기억 요구를 수반하는 탐색과제는 중년과 고령운전자 사이의 수행을, 반면 자극이심률 조건은 뇌졸중 여부에 따른 고령운전자 집단에서의 수행 차이를 민감하게 반영할 수 있음을 시사한다.

Identification of specific marker proteins in cells is useful for isolating cells and determining their cellular characteristics and functions. Based on our previous study showing that matrix metalloproteinase 9 (MMP-9) can be used as a marker for porcine spermatogonia, the expression pattern of MMP-9 was determined in both pre- (5-month old) and post-pubertal (11–month old) bovine testes. Histological analysis revealed that spermatogonia were located near the basement membrane in both testes, while spermatozoa were not detected in the 5-month old pre-pubertal bovine testes and epididymides. Mature spermatozoa were observed in the 11-month bovine testes and epididymides, and MMP-9 expression in 11-month old bovine testes was lower than 5-month old testes, according to reverse transcription-PCR and real-time-PCR data. To determine the specific expression sites of MMP-9 in the bovine testes, immunohistochemistry was performed. Expression of MMP-9 was observed in cells near the basement membrane of seminiferous tubules in both 5- and 11-month old testes. Furthermore, MMP-9 positive cells expressed protein gene product 9.5 (PGP9.5) and deleted in azoospermia (DAZL) that are already known as bovine spermatogonial stem cells markers. In the present study, MMP-9 expression was identified in both pre- and post-pubertal bovine spermatogonia expressing PGP9.5 and DAZL, and located near the basement membrane of seminiferous tubules. Thus, MMP-9 can be used as a marker for bovine spermatogonia, and may provide useful platforms for understanding the interaction between germ cells and extracellular matrix during spermatogenesis in the seminiferous tubules.

본 연구에서는 꽁치를 냉풍건조방법으로 생산한 과메기 의 성분 변화와 세척수 처리에 따른 미생물 제어효과를 조사하였다. 건조를 하기 전 시료의 수분 함량은 56.62% 였으나 초기 수분 함량이 급격히 감소하다가 시간이 지날 수록 완만해지는 결과를 보였다. 건조 처리 전의 과메기의 색도차는 42.40이었으나 온도와 건조시간이 증가함에 따라 색도차의 값이 감소하였다. 건조를 하지 않은 대조 구의 TBA 값은 0.219였고, 모든 온도 조건에서 건조가 진행될수록 산패도가 증가하였다. 과메기의 구성아미노산을 분석한 결과, 25℃에서 36시간을 건조시킨 처리구에서 총 아미노산 함량이 가장 높았으며 40℃에서 12시간을 건조 시킨 처리구가 총 아미노산 함량이 가장 낮았다. 건조온도와 시간에 따른 과메기의 지방산 분석 결과, 주요 지방 산은 14:0, 16:0, 18:1 등이 각각 18.15~20.96%, 28.06~ 32.51%, 17.06~19.81%로 분포하였다. Chlorine dioxide 100 ppm에서 60초 동안 세척한 구에서 미생물제어 효과가 가장 우수하였으며 과메기의 위해미생물 동정한 결과, Pseudomonas sp.와 Pseudomonas putida 로 두 균주가 조사되었다.

Volatile organic compounds(VOCs) detected frequently in the indoor air of child-care centers causes neurological disorders, lung, eyes, and bronchial irritation, and acute and chronic toxicity. In this study, the distributions of carcinogenic VOCs detected in child-care centers were characterized and a health risk assessment of the VOCs was performed, which can provide the necessary information for drawing up safety plans with respect to the concerned materials. The sampling of sites in day-care centers was undertaken two times: in the morning (10:00~12:00), and afternoon(16:00~20:00)-at 23 daycare centers located in Seoul, Korea from April, 2012 to July, 2012. The overall average concentrations of individual VOCs were benzene(1.61 μg/m3) > carbon tetrachloride (0.78 μg/m3) > chloroform(0.67 μg/m3) in order. Indoor/outdoor(I/O) ratios of benzene, carbon tetrachloride, chloroform were 1.33, 1.09, 1.72, respectively. Benzene and carbon tetrachloride are thought to be more strongly associated with outdoor sources as compared to chloroform. Spearman correlation of benzene, carbon tetrachloride between indoor and outdoor concentration showed statistically significant levels(p < 0.05). The linear correlations for benzene, styrene, and carbon tetrachloride were tested. A significant correlation was observed only for carbon tetrachloride, accounting for 83 % of the variance. The risk assessment of the carcinogenic VOCs for teachers, infants, and children showed that none of the targeted VOCs posed a serious risk.

The children of daycare center are sensitive to indoor environmental pollution. This study was a preliminary investigation for improving the environmental and healthy quality of daycare centers. The sampling of sites in daycare centers was undertaken three times such as day-morning (10:00-12:00), afternoon (16:00-20:00), following dawn (04:00-08:00)-at 21 daycare centers located in Seoul, Korea from April, 2012 to July, 2012. The mean concentrations of TVOC were 255.2, 217.0, and 439.4 μg/m3 at morning, afternoon, and following dawn, respectively. The daycare center indoor/outdoor ratios on the most targeted volatile organic compounds were above 1.0 except that for carbon tetrachloride, which was almost 1.0. Significant correlations (p<0.01) were observed between indoor and outdoor carbon tetrachloride, which implies that indoor carbon tetrachloride could be largely accounted for by outdoor sources. The other targeted indoor volatile organic compounds such as benzene, toluene, ethylbenzene, styrene, xylenes, chloroform showed no significant correlations with that of outdoor.

Spermatogenesis is initiated from spermatogonial stem cells (SSCs) that has an ability of self-renewal and unipotency to generate differentiating germ cells. The objective of this study is to develop the simple method for derivation of SSCs using non-sorting of both spermatogonia and feeder cells. Simply uncapsulated mouse testes were treated with enzymes followed by surgical mincing, and single cells were cultured in stempro-34TM cell culture media at 37℃. After 5 days of culture, aciniform of SSC colony was observed, and showed a strong alkaline phosphatase activity. Molecular characterization of mouse SSCs showed that most of the mouse SSC markers such as integrin α6 and β1, CD9 and Stra8. In addition, pluripotency embryonic stem cell (ESC) marker Oct4 were expressed, however Sox2 expression was lowered. Interestingly, expression of SSC markers such as Vasa, Dazl and PLZF were stronger than mouse ESC (mESC). This data suggest that generated mouse SSCs (mSSCs) in this study has at least similar biomarkers expression to mESC and mSSCs derived from other study. Immunocytochemistry using whole mSSC colony also confirmed that mSSCs generated from this study expressed SSC specific biomarkers such as c-kit, Thy1, Vasa and Dazl. In conclusion, mSSCs from 5 days old mouse testes were successfully established without sorting of spermatogonia, and this cells expressed both mESC and SSC specific biomarkers. This simple derivation method for mSSCs may facilitate the study of spermatogenesis.

본 연구는 연구개발 외주비중(총연구개발비 중 외부 연구개발비 비율)에 영향을 주는 기업요인을 분석하는 것을 목적으로 한다. 이와 관련된 4개의 가설을 검증하기 위해 통계청의 2006년 기업활동실태조사 데이터를 이용해 토빗분석을 수행했다. 본 논문의 주요 결과를 요약하면 다음과 같다. 첫째, 기술역량이 높은 기업일수록 연구개발 외주비중이 높다. 즉 근로자수 대비 특허수 또는 연구개발 집약도(매출액 대비 연구개발비)가 높은 기업은 연구개발 외주에 의존하는 경향이 있다. 그러나 사내연구소를 보유한 기업의 경우 연구개발 외주를 주더라도 그 비중이 낮았다. 둘째, 혁신활동의 보완재로 IT솔루션을 활용하는 기업은 연구개발 외주비중이 높다. 셋째, 대기업일수록 내부 연구개발보다 외부 연구개발비의 비중 이 높다.

Recently micro deep hole drilling is required in the whole industry. However, micro deep hole drilling has still much difficulty because of the lack of drill rigidity and the interruption of chip. We treated a micro deep hole(diameter 0.35mm, depth 3mm) used in a connector jack pin. Therefore, a surface roughness is very important. In this paper, we studied on the variation of the surface roughness for cutting conditions during micro deep hole drilling of Be-Cu material. Most of all, we tried to drill on CNC for the realization of automatization.