• Title/Summary/Keyword: and Teeth

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HISTOLOGIC FEATURE AND INFILTRATION OF ADHESIVE RESIN ACCORDING TO PRETREATMENT ON PROXIMAL EARLY CARIES LESION (평활면 초기 우식병소의 표면처리에 따른 조직상 및 접착제의 침투 양상 비교)

  • Kim, In-Young;Jeong, Tae-Sung;Kim, Shin
    • Journal of the korean academy of Pediatric Dentistry
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    • v.36 no.1
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    • pp.30-37
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    • 2009
  • Early enamel caries is commonly remineralized by the patient‘s improved oral hygiene or fluoridation, however the result is clinically unreliable. As an alternative, we tried to seal the lesions with low-viscosity light-curing resin. The aim of the present study was to search the proper methods of the adequate pretreatment prior to applying adhesive resin on natural proximal caries lesions. Thirty nine extracted deciduous molar teeth showing proximal early caries lesion were used for this study. They were divided into 5 groups : Group 1; only carefully cleaned with water, group 2; etched with 15% HCl for 15s, group 3; etched with 35% phosphoric acid for 15s, group 4; etched with 35% phosphoric acid for 30s, and group 5; cleaned with 0.5% NaOCl. Following results were obtained by evaluating with SEM and CLSM after applied with adhesive resin. 1. As a result of SEM evaluation, group 2 showed clearly removed surface layer, group 3,4 showed partially removed surface layer irregularly, group 5 showed slightly removed surface layer. 2. Group 2 showed the deepest infiltration depth, followed by group 4, group 3, group 5, group 1 and besides group 5, other groups showed significantly deep infiltration depth. (p < 0.01) In conclusion, the best methods of the adequate pretreatment on natural proximal caries lesion for deep infiltration of adhesive resin was to etch with 15% HCl for 15s.

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A Study on Denture Satisfaction in Rural Elderly People (농촌지역 노인의 의치만족도)

  • Lee, Ga-Ryoung;Yoo, Wang-Keun
    • Journal of agricultural medicine and community health
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    • v.35 no.1
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    • pp.56-66
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    • 2010
  • Objectives: The study aimed to explore dental status and denture satisfaction in some rural elderly people. Methods: A total of 546 participants aged over 65 years was surveyed cross-sectionally. The subjects were surveyed with regard to their denture satisfaction by a structured questionnaire. The Wilcoxon or Kruskal-Wallis test was used for analysis. Results: As for respondents' satisfaction for dentures by the Likert scale of 5 score, aesthetic satisfaction (3.73) was highest, followed by general satisfaction (3.56) and masticatory functions satisfaction (3.45). In addition, the educational level, occupation, monthly income, the number of remaining teeth, use of denture variables have statistically significant difference in the denture satisfaction of those elderly people interviewed. Conclusions: The results showed that denture satisfaction in some rural elderly people was different in each categories. Consequently, providing tailor-made oral health education programs for the effective denture management of the elderly people should be needed in order to improve the quality of life of the aged.

INHIBITORY EFFECT OF Er:YAG LASER ON THE GROWTH OF STREPTOCOCCUS MUTANS (Er:YAG 레이저 조사가 Streptococcus mutans의 증식억제에 미치는 효과)

  • Song, Gwang-Chul;Lee, Chang-Seop;Lee, Sang-Ho;Lee, Nan-Young
    • Journal of the korean academy of Pediatric Dentistry
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    • v.30 no.1
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    • pp.15-24
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    • 2003
  • The purpose of this study is to investigate the sterilization effect of Er:YAG laser against the intraoral acid producing bacterium, S. mutans, by irradiating the culture solution containing S. mutans KCTC 3065 with Er:YAG laser having a $650{\mu}m$ diameter beam through the non-contact method. We obtained the following results after examining the temperature changes of the culture solution, numbers of bacterial colonies, and acid-producing ability and attaching ability on teeth by measuring the amount of extracellular polysaccharide produced by S. mutans. The number of bacterial colony was decreased in $10{\mu}l$ culture solution irradiated with laser in overall compared to the control solution. The number decreased as the irradiation intensity and pulse repetition rate were larger and as the exposure time was increased. However, it did not change significantly in $100{\mu}l$ culture solution compared to the control solution. Although the acid-producing ability of S. mutans was inhibited for a certain duration after laser irradiation in 10r1 bacterial culture solution, it did not change in $100{\mu}m$ solution compared with the control solution. The amount of extracellular polysaccharide synthesized by S. mutans was partially decreased through laser irradiation in $10{\mu}m$ culture solution but did not change in $100{\mu}m$ culture solution. Based on these findings, we concluded that Er:YAG laser has an sterilization effect on S. mutans in which we presume that the mechanism is through the heat effect rather than the mechanical effect from development of ultrasound.

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A Case Study on Implementation of a School-Based Tooth Brushing Program in Gangneung City, Korea (강릉시 일부 초등학교 양치교실 운영 사례 보고)

  • Shin, Sun-Jung;Shin, Bo-Mi;Bae, Soo-Myoung
    • Journal of dental hygiene science
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    • v.13 no.4
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    • pp.518-527
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    • 2013
  • In 2011, South Korea's Ministry of Health and Welfare started a national tooth brushing room program without a pilot project. This study aimed to assess the effect of the implementation of this program in Gangneung, Korea. One-year outcomes of oral health behavior and self-reported oral symptoms in the study group after installation of the tooth brushing room were evaluated and compared with those of the control group using chi-square test. The prevalence rate of good self-rated oral health in grade 1-3 students increased from 35.7% immediately after installation to 48.9% after 6 months (p=0.031) compared to 37.3% in the control group (p=0.051). Immediately after installation of the tooth brushing room, 53.5% of grade 1-3 students in the study group brushed their teeth every day, but after 6 months, only 35.5% of students brushed daily (p<0.001) compared to 28.6% in the control group (p=0.007). The prevalence rate of bad breath in grade 1-3 students was 26.2% for the study group immediately after installation compared to 25.5% in the control group (p=0.065), but it declined 16.5% after 6 months (p=0.055). The prevalence rate of bad breath in grade 4~6 students was 14.7% for the study group after 6 months compared to 25.3% in the control group (p=0.016). We recommend the creation of a healthy school environment through a school-based tooth brushing program under the active supervision of classroom teachers and the continuous monitoring of program processes in order to promote children's oral health.

Effect of adhesive hydrophobicity on microtensile bond strength of low-shrinkage silorane resin to dentin (접착시스템의 소수성이 Low-shrinkage silorane resin과 상아질의 미세인장강도에 미치는 영향)

  • Cho, So-Yeun;Kang, Hyun-Young;Kim, Kyoung-A;Yu, Mi-Kyung;Lee, Kwang-Won
    • Restorative Dentistry and Endodontics
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    • v.36 no.4
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    • pp.280-289
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    • 2011
  • Objectives: The purpose of this study was to evaluate ${\mu}TBS$ (microtensile bond strength) of current dentin bonding adhesives which have different hydrophobicity with low-shrinkage silorane resin. Materials and Methods: Thirty-six human third molars were used. Middle dentin was exposed. The teeth were randomly assigned to nine experimental groups: Silorane self-etch adhesives (SS), SS + phosphoric acid etching (SS + pa), Adper easy bond (AE), AE + Silorane system bonding (AE + SSb), Clearfil SE bond (CSE), CSE + SSb, All-Bond 2 (AB2), AB2 + SSb, All-Bond 3 (AB3). After adhesive's were applied, the clinical crowns were restored with Filtek LS (3M ESPE). The 0.8 mm ${\times}$ 0.8 mm sticks were submitted to a tensile load using a Micro Tensile Tester (Bisco Inc.). Water sorption was measured to estimate hydrophobicity adhesives. Results: ${\mu}TBS$ of silorane resin to 5 adhesives: SS, 23.2 MPa; CSE, 19.4 MPa; AB3, 30.3 MPa; AB2 and AE, no bond. Additional layering of SSb: CSE + SSb, 26.2 MPa; AB2 + SSb, 33.9 MPa; AE + SSb, no bond. High value of ${\mu}TBS$ was related to cohesive failure. SS showed the lowest water sorption. AE showed the highest solubility. Conclusions: The hydrophobicity of adhesive increased, and silorane resin bond-strength was also increased. Additional hydrophobic adhesive layer did not increase the bond-strength to silorane resin except AB2 + SSb. All-Bond 3 showed similar ${\mu}TBS$ & water sorption with SS. By these facts, we could reach a conclusion that All-Bond 3 is a competitive adhesive which can replace the Silorane adhesive system.

Mechanism by which periodontitis may contribute to atherosclerosis (치주염이 동맥경화에 기여하는 기전에 관한 연구)

  • Han, Seung-Hee;Kim, Kyung-Hwa;Yang, Seung-Min;Chung, Hyun-Ju;Choi, Yoon-Sik;Han, Soo-Boo;Chung, Chong-Pyoung;Rhyu, In-Chul
    • Journal of Periodontal and Implant Science
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    • v.32 no.4
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    • pp.837-846
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    • 2002
  • 그람 음성균의 감염에 의한 만성 염증질환인 치주염이 동맥경화를 동반한 허혈성 심장질환 (협심증이나 심근 경색)을 일으킬 수 있는 위험인자로 작용할 수 있다는 보고가 있었다. 그러나, 그 기전에 관해서는 명확하게 알려져 있지 않다. 작용기전의 하나로서, 치주염에 의해 치주조직에서 국소적으로 생긴 염증성 싸이토카인(IL-1${\beta}$, IL-6, $PGE_2$, TNF-${\alpha}$)이 혈행을 따라 이동하여 심혈관에서 동맥경화를 일으킬 수 있다는 가설이 제시되고 있는데, 이 가설을 검증해 보고자 한다. 서울대학교 병원 순환기 내과에 불안정 협심증이나 심근경색으로 입원한 환자 및 과거 이 질환의 병력을 갖고 있거나 검진 목적으로 내원하여 관상동맥 조형술을 받은 환자들 중 동맥경화로 진단받은 사람을 실험군(24명)으로 하고, 동맥경화로 진단받지 않은 사람을 대조군(12명)으로 하였다. 치주질환의 활성도를 나타내는 치은 지수, 치태 지수, 치주낭 깊이, 부착 상실을 측정하였다. Paper strip을 실험대상 치아(Ramfjord's teeth)들 중에서 가장 깊은 치주낭을 가진 두 개의 치아를 택하여 각 치아의 가장 깊은 치주낭에 30초간 삽입한 후 밀폐된 plastic tube에 넣고 ELISA kit를 이용하여 IL-1${\beta}$, IL-6, TNF-${\alpha}$, $PGE_2$의 농도를 측정하였다. 환자의 plasma에서도 동일한 싸이토카인의 농도를 측정하였다. 설문조사를 통해 동맥경화의 위험 인자로 간주되어온 고혈압, 당뇨, 가족력, 심근경색이나 협심증의 기왕력, 흡연의 유무를 기록하였다. 혈액검사를 하여 total cholesterol, triglycerides, LDL cholesterol, HDL cholesterol, WBC, CRP (C-reactive protein)의 농도를 측정하였다. 치주조직에 대한 임상 검사 결과 치은의 염증상태를 나타나는 지표인 치은 지수에서만 실험군이 대조군에 비해 유의할 정도 (p=0.0174)로 높게 나타났고, 만성적인 염증의 결과로 인한 치조골의 사실 정도를 나타내는 치주낭 깊이나 부착 상실에서는 유의할 만한 차이를 보이지 않았다. 치주낭에서 측정한 염증성 싸이토카인 중 IL-1${\beta}$, $PGE_2$가 실험군에서 유의할 만한 차이 (p=0.005, 0.022)를 보이며, 더 높은 농도로 나타났고, TNF-${\alpha}$는 대조군에서 유의성 있게 (p=0.009) 높게 나타났다. 그러나, plasma의 싸이토카인이나, serum lipid/lipoprotein, C-reactive Protein, WBC는 유의할 만한 차이를 보이지 않았다. 또한 치은열구액내의 싸이토카인과 이에 상흥하는 싸이토카인 간에 상관관계는 관찰되지 않았다. 다변량 로지스틱 회귀분석 결과, 치은열구액내의 IL-1${\beta}$와 TNF-${\alpha}$ 만이 동맥경화와 유의성 있는 관련성을 보였고, 특히 IL-1${\beta}$와 교차비는 273으로 상당한 관련성을 보여주었다. 결론적으로, 치주조직에서 국소적으로 생긴 염증성 싸이토카인이 그대로 혈행으로 이동하여 혈장내의 싸이토카인 농도를 높이는 것은 아니다. 그러나, 치주염으로 인해 치은열구내액내에 국소적으로 증가된 염증성 싸이토카인은 동맥경화와 상당한 관련성을 가진다.

THE EFFECT OF ND:YAG LASER IRRADIATION ON THE FORMATION OF CALCIUM FLUORIDE AND ACID RESISTANCE OF TOOTH ENAMEL (Nd:YAG 레이저 조사가 Calcium Fluoride 형성 및 치아 내산성에 미치는 영향)

  • Lee, Jae-Ho;Sohn, Heung-Kyu;Kim, Seong-Oh;Park, Kwang-Kyun;Choi, Byung-Jai
    • Journal of the korean academy of Pediatric Dentistry
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    • v.26 no.2
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    • pp.377-398
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    • 1999
  • Calcium fluoride, created by topical fluoride application, is the reservoir for fluoride ion regulated by pH in the oral environment. Therefore, the amount and the maintenance of calcium fluoride have an important role in preventing dental caries. The aim of this study is to evaluate the effect of Nd:YAG laser irradiation on the generation of calcium fluoride and the acid resistance of tooth enamel. The bovine anterior permanent teeth were prepared (n=276), and divided into following groups : no treatment (control) fluoride application alone, laser irradiation alone, laser irradiation after fluoride application, and fluoride application after laser irradiation. And each group was subdivided based on the application time of 1.23% acidulated phosphate fluoride (APF) (5 min and 30 min) and the irradiation energy of Nd:YAG laser ($20J/cm^2\;and\;40J/cm^2$). In case of fluoride application, each group was divided according to KOH treatment. Twenty three treatment conditions were made for this experiment and twelve specimens were assigned to each treatment condition. In each treatment condition, ten specimens were used for chemical analysis and two specimens were observed under SEM. In groups without treating KOH, fluoride content and the depth of enamel dissolved were measured using enamel biopsy technique. In groups with treating KOH, the amount of calcium fluoride was measured by the treatment with 1 M KOH for 24 hours and enamel biopsy was performed after KOH treatment. The results were analyzed by the fluoride content and the depth of enamel dissolved by enamel biopsy, amount and thickness of calcium fluoride, and the surface structures of enamel. The results are as follows: 1. In groups without treating KOH, the fluoride content of removed enamel showed a positive relationship with the energy density of laser when the laser irradiated before fluoride application 2. In groups without treating KOH, the depth of enamel dissolved decreased more with the combined laser and fluoride treatment than with laser or fluoride treatment, except for the case of $20J/cm^2$ laser irradiation after 5 minute fluoride application (p<0.05). 3. The amount of calcium fluoride did not increased by laser treatment with no statistical significance(p>0.05). 4. The particle size of calcium fluoride increased in case of fluoride treatment after laser irradiation, compared with fluoride application alone. In case of laser treatment after fluoride application, the particle size of calcium fluoride increased and some of the particles fused as well. 5. There were no significant differences in the fluoride content of dissolved enamel between groups without treating KOH and control group, except for the case of laser irradiation after treatment of APF for 30 minutes (p>0.05). 6. In groups with treating KOH, depth of removed enamel in the groups of combined treatment with laser and fluoride was shallower than that in fluoride application groups (p<0.05). 7. In groups without treating KOH, the relationship between fluoride content and the depth of enamel dissolved showed more negative (Spearman correlation coefficient: -0.6281) than in groups with treating KOH (Spearman correlation coefficient: -0.3792). The greater amount of calcium fluoride could be found in case where there was a significant differences of the depth of enamel dissolved between groups with and without treating KOH. From these results, it can be concluded that laser seems to be a little effects on the amount of calcium fluoride formation, but has some effect on the lowering the solubility of calcium fluoride. As the combined treatment of laser and fluoride application showed more effective acid-resistant property, more extended recall period for fluoride application can be achieved with this combined treatment in the clinic.

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An influence of operator's posture on the shape of prepared tooth surfaces for fixed partial denture (진료자세가 고정성 국소의치의 지대치 삭제에 미치는 영향)

  • Won, In-Jae;Kwon, Kung-Rock;Pae, Ah-Ran;Choi, Dae-Gyun
    • The Journal of Korean Academy of Prosthodontics
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    • v.49 no.1
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    • pp.38-48
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    • 2011
  • Purpose: Dentists suffer back, neck and shoulder pain during their careers due to bad operating posture. If dentists have a good operating posture ergonomically, there would be less pain and discomfort in the shoulder and back. Therefore, dentists should learn the Home position which enables dentists to approach a stable posture ergonomically. This study was to compare tooth preparation in the Home position and the Random position, and evaluate the clinical efficacy of the Home position. Materials and methods: Tooth preparation for fixed partial denture was performed on the maxillary left 2nd premolar and maxillary left 2nd molar at the two different operating positions were compared. The amount of occlusal reduction, marginal width, subgingival margin depth, and convergence angle were measured. A T-test was performed separately to compare the results of the Random position and the Home position. Results: 1. The amounts of average thickness of occlusal reduction on fossa were deficient to the ordered ones in the Random position and the Home position (P > .05). 2. The average subgingival margin depth of prepared margin on maxillary left 2nd premolar, maxillary left 2nd molar were excessive in the Random position than in the Home position. On the maxillary left 2nd premolar, there was no statistical difference in the Random position and the Home position except Distal midline, DL line angle, Lingual midline, ML line angle (P< .05). On the maxillary left 2nd molar, there was no statistical difference in the Random position and the Home position (P < .05). 3. Average convergence angle in the Random position and the Home position were excessive compared to the ordered angle. There was no statistical difference in the Random position and the Home position (P > .05). 4. Analysis of pearson correlation : In the Random position, the amounts of average thickness of occlusal reduction, the average subgingival margin depth of prepared margin, convergence angle were significantly associated with each other (P < .05). But in the Home position, they were not significantly associated with each other (P < .05). 5. The time needed for preparation in the Home position was faster or equal than that of the Random position as time went on. Conclusion: In conclusion, there were no significant differences between Home position and Random position in measures of occlusal reduction, marginal width, marginal depth, convergence angle. However, preparation time and incidence of damaging adjacent teeth were less in Home position than in Random position. Therefore, if trained properly, Home position which is more ergonomically stable can be adopted for clinical use.

Dosimetric Evaluation of a Small Intraoral X-ray Tube for Dental Imaging (치과용 초소형 X-선 튜브의 선량평가)

  • Ji, Yunseo;Kim, YeonWoo;Lee, Rena
    • Progress in Medical Physics
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    • v.26 no.3
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    • pp.160-167
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    • 2015
  • Radiation exposure from medical diagnostic imaging procedures to patients is one of the most significant interests in diagnostic x-ray system. A miniature x-ray intraoral tube was developed for the first time in the world which can be inserted into the mouth for imaging. Dose evaluation should be carried out in order to utilize such an imaging device for clinical use. In this study, dose evaluation of the new x-ray unit was performed by 1) using a custom made in vivo Pig phantom, 2) determining exposure condition for the clinical use, and 3) measuring patient dose of the new system. On the basis of DRLs (Diagnostic Reference Level) recommended by KDFA (Korea Food & Drug Administration), the ESD (Entrance Skin Dose) and DAP (Dose Area Product) measurements for the new x-ray imaging device were designed and measured. The maximum voltage and current of the x-ray tubes used in this study were 55 kVp, and 300 mA. The active area of the detector was $72{\times}72mm$ with pixel size of $48{\mu}m$. To obtain the operating condition of the new system, pig jaw phantom images showing major tooth-associated tissues, such as clown, pulp cavity were acquired at 1 frame/sec. Changing the beam currents 20 to $80{\mu}A$, x-ray images of 50 frames were obtained for one beam current with optimum x-ray exposure setting. Pig jaw phantom images were acquired from two commercial x-ray imaging units and compared to the new x-ray device: CS 2100, Carestream Dental LLC and EXARO, HIOSSEN, Inc. Their exposure conditions were 60 kV, 7 mA, and 60 kV, 2 mA, respectively. Comparing the new x-ray device and conventional x-ray imaging units, images of the new x-ray device around teeth and their neighboring tissues turn out to be better in spite of its small x-ray field size. ESD of the new x-ray device was measured 1.369 mGy on the beam condition for the best image quality, 0.051 mAs, which is much less than DRLs recommended by IAEA (International Atomic Energy Agency) and KDFA, both. Its dose distribution in the x-ray field size was observed to be uniform with standard deviation of 5~10 %. DAP of the new x-ray device was $82.4mGy*cm^2$ less than DRL established by KDFA even though its x-ray field size was small. This study shows that the new x-ray imaging device offers better in image quality and lower radiation dose compared to the conventional intraoral units. In additions, methods and know-how for studies in x-ray features could be accumulated from this work.

A Study on the Utilzation of Two Furrow Combine (2조형(條型) Combine의 이용(利用)에 관(關)한 연구(硏究))

  • Lee, Sang Woo;Kim, Soung Rai
    • Korean Journal of Agricultural Science
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    • v.3 no.1
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    • pp.95-104
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    • 1976
  • This study was conducted to test the harvesting operation of two kinds of rice varieties such as Milyang #15 and Tong-il with a imported two furrow Japanese combine and was performed to find out the operational accuracy of it, the adaptability of this machine, and the feasibility of supplying this machine to rural area in Korea. The results obtained in this study are summarized as follows; 1. The harvesting test of the Milyang #15 was carried out 5 times from the optimum harvesting operation was good regardless of its maturity. The field grain loss ratio and the rate of unthreshed paddy were all about 1 percent. 2. The field grain loss of Tong-il harvested was increased from 5.13% to 10.34% along its maturity as shown in Fig 1. In considering this, it was needed that the combine mechanism should be improved mechanically for harvesting of Tong-il rice variety. 3. The rate of unthreshed paddy of Tong-il rice variety of which stem was short was average 1.6 percent, because the sample combine used in this study was developed on basisof the long stem variety in Japan, therefore some ears owing to the uneven stem of Tong-il rice could nat reach the teeth of the threshing drum. 4. The cracking rates of brown rice depending mostly upon the revolution speed of the threshing drum(240-350 rpm) in harvesting of Tong-il and Milyang #15 were all below 1 percent, and there was no significance between two varieties. 5. Since the ears of Tong-il rice variety covered with its leaves, a lots of trashes was produced, especially when threshed in raw materials, and the cleaning and the trashout mechanisms were clogged with those trashes very often, and so these two mechanisms were needed for being improved. 6. The sample combine of which track pressure was $0.19kg/cm^2$ could drive on the soft ground of which sinking was even 25cm as shown in Fig 3. But in considering the reaping height adjustment, 5cm sinking may be afford to drive the combine on the irregular sinking level ground without any readjustment of the resaping height. 7. The harvesting expenses per ha. by the sample combine of which annual coverage area is 4.7 ha. under conditions that the yearly workable days is 40, percentage of days being good for harvesting operation is 60%, field efficiency is 56%, working speed is 0.273m/sec, and daily workable hours is 8 hrs is reasonable to spread this combine to rural area in Korea, comparing to the expenses by the conventional harvesting expenses, if mechanical improvement is supplemented so as to harvest Tong-il rice. 8. In order to harvest Tong-il rice, the two furrow combine should be needed some mechanical improvements that divider can control not to touch ears of paddy, the space between the feeding chain and the thrshing drum is reduced, trash treatment apparatus must be improved, fore and rear adjust-interval is enlarged, and width of track must be enlarged so as to drive on the soft ground.

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