• Applied Microscopy
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• v.30 no.3
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• pp.285-293
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• 2000

The present study has been carried out to investigate the effect of fluoride toxicity on the morphology as well as inorganic chemical constituents of rat teeth. Rats were administered sodium fluoride at dose of 0 ppm, 100 ppm, 200 ppm and 300 ppm at the beginning of pregnancy. Animals were perfused intravascularly with glutaraldehyde and the incisors were removed. Changes in the protein composition of the secretory and maturation enamel were investigated using polyacrylamide gel electrophoresis (SDS PAGE). And the enamel surface of incisors was examined under scanning electron microscope (SEM). Changes of protein quantities were found significantly in high levels fluoride administration for experimental groups compared with control. The SDS PAGE analysis demonstrated as follows In control group, secretory phase enamel protein, amelogenins, was detected more quantities than experimental group. The enamelin, presence in maturation phase enamel , showed more quantifies than control enamel with an increasing fluoride concentration in the drinking water. Also, the scanning electron micrographic data showed hypoplastic, tough, uneven, pitted and cracked enamel surfaces covered with granular deposits as a result of excessive intake of fluoride. From these results we conclude that high dose of fluoride administration leads to severe structural alterations on the enamel surface and these structural changes could be through defective mineralization.

• Journal of Life Science
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• v.16 no.6
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• pp.925-931
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• 2006

Culture of osteoblast is extremely valuable in analyzing biological features that are specific to bone. ENA-A, ENA actimineral resource A, is a seaweed origin alkaline water. To investigate the bioactivity of ENA which act on bone metabolism, we studied the effects of a ENA on the activity of osteoblast MC3T3-E1 cells. ENA (1, 2, 4%) dose-dependently increased survival (p<0.05) and alkaline phosphatase activity (p<0.05) on MC3T3-E1 cell. And examined histochemistry and nodule formation according to the time course. To determine the expression patterns of bone-related proteins during the MC3T3-E1 osteoblast-like cell differentiation by using RT-PCR. This study suggest that ENA may promote the function of osteoblastic cells and play an important role in bone formation.

• Journal of the Korean School Mathematics Society
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• v.24 no.1
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• pp.83-105
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• 2021

In this paper, we analyzed the misconceptions and errors incurred during factorization learning. We also examined whether online individualization classes had a positive effect on students' mathematical achievement. The experiment was conducted for 4 weeks (16 times in total) on middle school juniors in rural areas of Gyeonggi Province, where the influence of private extra education was small. In the class, the 'Google Classroom' was used as a LMS, the video lecture was uploaded to YouTube, and the teacher interacted with the students through "Zoom" and "Facetalk". In the online class situation, students' assignments and test answers were checked in real time through 'Google Classroom', and immediate feedback was provided to the experimental class group's students. However, for the control group students, feedback was provided only to those who desired. A total of 7 achievement evaluations were conducted in the order of pre-test, formative evaluation (5 times), and post-test to confirm the change in students' ability improvement and achievement. Through the formative evaluation analysis, it was possible to grasp the types of errors and misconceptions that occured during the factorization process. Students' errors were divided into four types: theorem or definition distortion error, functional errors such as calculation, operation, and manipulation, errors that do not verify the solution, and no response. As a result of ANCOVA, the two groups did not show any difference from the 1st to 4th formative assessment. However, the 5th formative assessment and post-test showed statistically significant differences, confirming that online individualization classes contributed to improvemed achievement.

• The Korean Journal of Nuclear Medicine
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• v.4 no.1
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• pp.27-36
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• 1970

적혈구(赤血球) 수명의 측정에는 $^{51}Cr$-표지적혈구법(標識赤血球法)이 임상적(臨床的)으로 이용(利用)되고 있으며 이는 이론상(理論上) steady state 즉(卽) 측정기간(測定期間)동안 순환(循環) $^{51}Cr$량(量)-적혈구량(赤血球量)이 일정(一定)할 때에 한(限)하여 유효(有效)하며 unsteady state 때는 true red cell survival을 알기 위하여서는 측정치에 영향을 주는 요인(要因)에 대하여 각각(各各) 교정(校正)해 줄 필요(必要)가 있다. 이 요인(要因)중에 특히 실혈(失血)로 인(因)한 영향에 관(關)하여는 계통적인 연구(硏究)가 적다. 이에 저자(著者)들은 $^{51}Cr$표지적혈구법(標識赤血球法)을 이용(利用)하여 실혈(失血)이 적혈구(赤血球) 수명측정(測定)에 미치는 영향을 인체(人體)에서 실험 관찰하여 몇가지 성적을 얻었다. 연구대상(硏究對象)은 총(總) 56명(名)의 청장년(靑壯年)으로 급성실혈군(急性失血群)과 만성실혈군(慢性失血群)으로 구분(區分)하여 급성실혈군(急性失血群)은 위장출혈등(胃腸出血等)이 없는 2대(代)의 의대생(醫大生)으로 $^{51}Cr$표지적혈구법(標識赤血球法)을 사용하여 적혈구(赤血球) 수명을 측정하는 동안($10{\sim}14$ 일간(日間)) 1일당(日當) 10ml(6명(名)), 25ml(4명(名)), 50ml(4명(名)), 75ml(4명(名)), 100ml(6명(名))를 각각(各各) 사혈(瀉血)한 군(群)과 10일간(日間) 1,000ml를 사혈한 군(群) 즉 200ml씩 5회(回)(4명(名)), 500ml씩 2회(回)(4명(名))로 세분(細分)하였으며 만성실혈군(慢性失血群)은 직업적인 공혈자(供血者)로 반복사혈로 생긴 9명(名)의 빈혈자와 십이지장충증(十二指腸蟲症)에 감염(感染)되어 구충(驅蟲)한 중등도(中等度)의 철결핍성 빈혈환자 7명(名)으로 나누어 관찰하였다. 측정(測定) 방법(方法)으로는 Gray 및 Sterling법(法)을 개설한 방법(方法)으로 $^{51}Cr$표지적혈구(標識赤血球)의 계측시료(計測試料)로서 전혈(全血) 및 적혈구(赤血球)를 사용(使用)하였다. 실험(實驗)성적은 1. 1일당(日當) 실혈량(失血量)이 증가(增加)할수록 적혈구(赤血球)수명($T\frac{1}{2}$)은 짧아짐을 알 수 있었다. 즉(卽) 1일당(日當) $20{\sim}50ml$ 사혈군에서는 $T\frac{1}{2}$이 현저히 짧아지는 rapid phase을 나타내고 1일당(日當) 50ml이상(以上) 사혈군에서는 짧아지는 정도(程度)가 완만한 slow phase을 나타낸다(Fig. 6). 2. 1일량(日量) 10ml 및 25ml식(式) 사혈한 군(群)의 적혈구수명(赤血球壽命)을 측정(測定)하는데 있어 적혈구(赤血球)를 사용하였을 때에는 $T\frac{1}{2}$측 정치에 유의한 차(差)가 없었으며 이 범위 내에서는 Hct., Hb. 및 혈청철치(血淸鐵値)도 역시 유의한 차(差)가 없었다. 3. 1일량(日量) 50ml 및 75ml, 100ml씩 사혈한 군(群)에서는 적혈구(赤血球)만을 사용(使用)하였을 때와 전혈(全血)을 시료(試料)로 하였을 때 사이에 $T\frac{1}{2}$의 측정치에 유의한 차(差)가 있었으며 이 때는 Hct., Hb. 및 혈청철치(血淸鐵値)에도 변화(變化)가 있었다. 즉(卽), 전혈(全血)을 사용한 적혈구(赤血球) 수명($T\frac{1}{2}$)의 측정치가 적혈구(赤血球)만를 사용(使用)한 적혈구(赤血球) 수명($T\frac{1}{2}$)의 측정치 보다 짧았다. 4. 일정(一定)기간(10 일(日)) 사혈의 총량(1000ml)이 같을 매는 200ml를 5회(回) 사혈한 군(群)이나 500ml를 2회(回) 사혈한 군(群) 사이에 적혈구(赤血球) 수명($T\frac{1}{2}$)에 유의(有義)한 차(差)를 볼 수 없었다. 5. 직업적 공혈자의 반복사혈로 인(因)한 만성(慢性) 빈혈환자 9명(名)에서의 $^{51}Cr$적혈구(赤血球)수명($T\frac{1}{2}$) 측정치는 평균(平均) 19.2일(日)로 짧아져 있으나 적혈구수명측정전후(赤血球壽命測定前後)에 충분(充分)한 철제(鐵劑)를 투여(投與)하여 Hct., Hb. 및 혈청철치(血淸鐵値)를 증가(增加)시켰으며 이때 볼 수 있었든 Hct치(値)를 규준(規準)하여 교정한 적혈구(赤血球)수명($T\frac{1}{2}$)은 거의 정상(正常)범위 안에 있어(27.6일(日)) 이러한 인자(因子)를 고려하지 않으면 잘못 이해할 수가 있다. 6. 구충자충(鉤蟲仔蟲)을 구충한 7명(名)의 중등도(中等度) 철(鐵)결핍성 빈혈환자에서의 적혈구(赤血球)수명($T\frac{1}{2}$) 측정치는 25일(日)$\sim$31일(日)로 평균(平均) 28일(日)이었으며, 이때 장 출혈량은 1일(日) $1.0{\sim}3.5ml$이었다. 단시일내의 급성실혈시에는 이와같은 소량의 실혈(失血)도 적혈구(赤血球)수명($T\frac{1}{2}$) 측정치에 영향을 보여 줌을 알 수 있었다. 따라서 이러한 정도의 실혈은 실험오차에 기인하는 것인지 아니면 장기 출혈에서는 이러한 소량의 실혈이 적혈구(赤血球)수명($T\frac{1}{2}$) 측정에 영향을 미치지 않는 것인지는 아직 확실히 말할 수 없다. 8. $^{51}Cr$-표지적혈구(標識赤血球)로 측정한 적혈구(赤血球)수명($T\frac{1}{2}$)은 측정시의 실혈량(失血量)에 큰 영향을 받음을 알 수 있으며 저자(著者)들은 $^{51}Cr$표지적혈구(標識赤血球)를 이용(利用)한 적혈구(赤血球) 수명 측정때 검사기간중 실혈량이 적혈구수명치(赤血球壽命値)에 미치는 관계를 상술(上述)한 실험치(實驗値)를 기초(基礎)로 하여 다음과 같을 교정식(校正式)을 고찰(考察)해 보았다. $^{51}Cr\;T\frac{1}{2}=17.0e^{-0.0495}+18.4e^{-0.000924x}$ 단(但) X : 1일(日) 실혈량(失血量)(단위(單位) ml)

• Journal of dental hygiene science
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• v.5 no.2
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• pp.63-70
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• 2005

The relation among the variables of dental hygienists' both personal protection and infection prevention education was investigated in order to identify the necessity of realization of personal protection and utilize in the development of educational programs. The study tools included structured questionnaire and in-home interview. Data analysis included frequency and t-test, and the relations among the variables were as below: (1) Dental hygienist's maskwearing was most well observed in Kyonggi-do (90.0%) by locations, and in the dental hospitals (84.8%) by working places, which was statistically significant. (2) Glove-wearing was most well observed in the university and the higher graduates population (59.1%) by academic background, and in the dental hospital (73.9%) by working place, which was statistically significant. (3) Protection glasses-wearing was most well observed in Guns, Ups, and Myons (82.4%) by locations, which was statistically significant. (4) Uniforms were hand-laundered at home in the 40.9% of the university and the higher graduates, which was statistically significant. (5) About infection management, 67.0% of 2-year college graduates and 71.7% of the respondents from dental hospitals had been educated during their college days, which was statistically significant. (6) About the necessity of infection education, 77.3% of the university graduates responded it is very necessary, which was statistically significant.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1302-1310
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• 2004

The purpose of this study was to investigate whether a web-based nutrition counseling could lead to beneficial outcomes in food intake and serum lipids of patients with hyperlipidemia. Forty hyperlipidemic patients, twenty of them were hypercholesterolemia and the other twenty were hypertriglyceridemia, participated in a web-based nutrition counseling program. At the first nutrition counseling, the patients were counselled through interview and then follow up nutrition counseling was accomplished four times during eight weeks through a web-based internet program. Various markers of disease risk including anthropometric indices, food intakes and serum lipid levels were measured before and after the web-based nutrition counseling. After nutrition counseling, body mass index significantly decreased in both groups and waist to hip ratio significantly decreased in male hypercholesterolemic patients (p<0.05). Total-cholesterol decreased from 262.2 mg/dL to 234.9 mg/dL, LDL-cholesterol decreased from 186.8 mg/dL to 160.5 mg/dL in hypercholesterolemic patients, triglyceride decreased from 288.6 mg/dL to 211.9 mg/dL and total-cholesterol decreased from 217.2 mg/dL to 198.7 mg/dL in hypertriglyceridemic patients after nutrition counseling. Anthropometric value and nutrient intakes were improved after nutrition counseling. Energy, fat and saturated fatty acid intakes decreased significantly in both groups (p<0.05). Therefore, this study shows that the web-based nutrition counseling is effective in improving food habit and influences positively in serum lipid levels of the patients. In addition, these results indicate that internet presents us with potential as a new medium for nutrition counseling in informationized society.

• Radiation Oncology Journal
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• v.18 no.3
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• pp.194-199
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• 2000

Purpose : Then determining the lower margin of post-operative pelvic radiation therapy field according to the traditional method (recommended by Gunderson), the organs located in the low pelvic cavity and the perineum are vulnerable to unnecessary radiation. This study evaluated the effect of individualized determination of the lower margin at 2 cm to 3 cm below the anastomotic site on the failure patterns. Materials and Methods . Authors included ぉ patients with modified Astler-Coiler (MAC) stages from B2 through C3, who received low anterior resection and post-operative pelvic radiation therapy from Sept. 1994 to May 1998 at Samsung Medical Center, Sungkyunkwan University. The numbers of male and female patients were 44 and 44, and the median age was 57 years (range: 32-81 years). Three field technique (posterior-anterior and bilateral portals) by 6, 10, 15 MV X-rays was used to deliver 4,500 cGy to the whole pelvis followed by Sn cGy's small field boost to the tumor bed over 5.5 weeks. Sixteen patients received radiation therapy by traditional field margin determination, and the lower margin was set either at the low margin of the obturator foramen or at 2 cm to 3 cm below the anastomotic site, whichever is lower. In 72 patients, the lower margin was set at 2 cm to 3 cm below the anastomotic site, irrespectively of the obturator foramen, by which the reduction of radiation volume was possible in 55 patients ($76\%$). Authors evaluated and compared survival, local control, and disease-free survival rates of these two groups. Results : The median follow-up period was 27 months (range : 7-58 months). MAC stages B2 in 32($36\%$), B3 in 2 ($2\%$), Cl in 2 ($2\%$), C2 in 50 ($57\%$), and C3 in 2 ($2\%$) Patients, respectively. The entire patients' overall survival rates at 2 and 4 years were $94\%$ and $68\%$, respectively, and disease-free survival rates at 2 and 4 years were $86\%$ and $58\%$, respectively. The first failure sites were local only in 4, distant only in 14, and combined local and distant in 1 patient, respectively. There was no significant difference with respect to local control and disease-free survival rates ( p=0.42, p=0.68) between two groups of different lower margin determination policies. Conclusion : The new concept in the individualized determination of the lower margin depending on the anastomotic site has led to the equivalent local control and disease-free survival rates, and is expected to contribute to the reduction of unnecessary radiation-related morbidity by reduction of radiation volume, compared with the traditional method of lower margin determination.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.469-485
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• 1996

Orthodontic patients are individuals that grow and develop ; therefore selection of the proper time for orthodontic treatment is considered to be one of most difficult and yet difficult factor. Since the development of cephalometric X-ray, amount and Pattern of craniofacial growth change with aging could be predicted and be came useful in the process of orthodontic treatment. The relationship between the mean values of cephalometric measurements and body height and weight was studied among the groups(boys and girls) of Korean children from the ages 6-years to 17-years. 409 boys and 437 girls with no abnormality in growth and development and no history of orthodontic treatment from the ages of 6 years to 17 years were chosen as subjects Cephaloment X-ray were taken for 3 years and hard tissue analysis based on Burstone's COGS, which was devided into measurements of 6 parts(Cranial base, Maxillar and Mandible, Dental measurements). The relationship between craniofacial growth and height & weight was studied. The following conclusions were obtained : 1. The maximum growth in the measurements of cranial base, N-Ar(FH), N-Ba(FH) corresponded with the age with the maximum increase in body height & weight in both boys and girls. 2. Genial angle gradually decreased with aging in both boys and girls. 3. N-ANS(L) showed greater amount of growth than ANS-Ne(L), and this had greater influence on facial profile. 4. N-A-$Pog^{\circ}$ decreased with aging, and mandibular growth exceeded maxillary growth in amount and rate. 5. Length of Y-axis Increased, but Y-axis to FH plane remained constant. This show that mandible grows at a constant angulation to cranial base. 6. As permanent teeth erupt, interincisal angle deceased.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.963-978
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• 1997

Orthodontic patients are individuals that grow and develop ;therefore selection of the proper time for orthodontic treatment Is considered to be one of the most difficult and yet difficult factor.Since the development of cephalometric X-ray, amount and pattern of craniofacial growth change with aging could be predicted and became useful in the process of orthodontic treatment. The relationship between the mean values of cephalometric measurements and body height and weight was studied among the groups(boys and girls) of Korean children from the ages of 3-years to 12-years. 126 boys and 90 girls with no abnormality in growth and development and no history of orthodontic treatment from the ages of 3 years to 12 years were chosen as subjects: Cephalometric X-ray were taken for 2 years and hard tissue analysis based on Burstone's COGS, which was divided into measurements of 6 parts (Cranial base, Maxillar and Mandible, Vertical measurements, Horizontal measurements, Basal bone relationship, Dental measurements). The relationship between craniofacial growth and body height & weight was studied. The following conclusions were obtained : 1. The maximum growth in the measurements of cranial base, N-Ar(FH), N-Ba(FH) corresponded with the age with the maximum increasein body height & weight in both boys and girls. 2. Genial angle gradually decreased with aging in both boys and girls. 3. N-ANS(L) showed greater amount of growth than ANS-Me(L), and this had greater influence on facial profile. 4. $N-A-Pog^{\circ}$ decreased with aging, and mandibular growth exceeded maxillary growth in amount and rate. 5. Length of Y-axis increased, but Y-axis to FH plane remained constant. This show that mandible grows at a constant angulation to cranial base. 6. As Permanent teeth erupt, interincisal angle deceased.

• Journal of Chest Surgery
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• v.36 no.7
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• pp.472-482
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• 2003

Recent studies have demonstrated that cerebral desaturation during rewarming period of CPB was associated with postoperative neurologic dysfunction. The prevention of cerebral desaturation during CPB may reduce the incidences of neurologic and neuropsychological complications. The present study was prospectively undertaken to compare the clinical effects between two strategies (hypercapnic CPB and high flow CPB) to prevent cerebral desaturation for establishing a proper CPB technique. Material and Method: Thirty-six adult patients scheduled for elective cardiac surgery were randomized into either hypercapnic (Pa$CO_2$ 45~50mmHg, n＝18) or high flow group (flow rate 2.75 L/ $m^2$/min and Pa$CO_2$ 35~40mmHg, n＝18) during rewarming period of CPB. In each patient, middle cerebral artery blood flow velocity ( $V_{MCA}$), cerebral arteriovenous oxygen content difference (C(a-v) $O_2$), modified cerebral metabolic rate for oxygen (MCMR $O_2$), cerebral oxygen transport rate ( $T_{E}$ $O_2$), incidence of cerebral desaturation (internal jugular bulb blood oxygen saturation $\leq$ 50%), increased rate of S-100 $\beta$ concentration, and arterial and internal jugular bulb blood gas were measured during the five phases of the operation; Pre-CPB, CPB-10 min (steady-state CPB, nasopharyngeal temperature 29~3$0^{\circ}C$), Rewarm-1 (rewarming phase, nasopharyngeal temperature 33$^{\circ}C$), Rewarm-2 (nasopharyngeal temperature 37$^{\circ}C$), and CPB-off. Incidence of postoperative delirium and duration were assessed in all patients. All variables were compared between the two groups. Result: $V_{MCA}$ (157.88$\pm$10.87 vs 120.00$\pm$6.18%, p＝0.006), internal jugular bulb $O_2$ saturation (68.01$\pm$2.75 vs 61.28$\pm$2.87%, p＝0.03) and $O_2$ tension (41.01$\pm$2.25 vs 32.02$\pm$ 1,67 mmHg, p＝0.03), and $T_{E}$ $O_2$(110.84$\pm$7.41 vs 81.15$\pm$8.11%, p＝0.003) at rewarming periods were higher in the hypercapnic group than in the high flow group. C(a-v) $O_2$ (4.0$\pm$0.30 vs 4.84$\pm$0.38 mg/dL, p＝0.04), COE (0.36$\pm$0.03 vs 0.42$\pm$0.03, p＝0.04), increased rate of S- 100$\beta$ (391.67$\pm$23.40 vs 940.0$\pm$17.02%, p＝0.003), and incidence of cerebral desaturation (2 vs 4 patients, p＝0.04) at rewarming periods, and duration of postoperative delirium (18 vs 34 hr, p＝0.02) were low in the hypercapnic group compared to the high flow group. Conclusion: These results indicate that hypercapnic CPB may provide relatively diminished cerebral injury and beneficial effects for cerebral metabolism relatively compared to high flow CPB.low CPB.