• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.5
• /
• pp.588-595
• /
• 2016

This paper is a study on head bolts that are used in A/C compressors to reduce production cost and solve leak problems on the head bolt seat area that causes massive intermittent malfunctioning during production. In this study, the pre-heat treated steel, which was used as a material in the head bolt, eliminated the heat treatment process after forging. The pre-heat treated steel head bolts, which have 10 % lower tensile strength than the conventional SCM 435 head bolts, were selected after considering the results of creeping rupture properties, axial force, and stress concentration per tensile strength variation. Then, the performance test and the durability test with the A/C compressor that was assembled with the pre-heat treated steel head bolts were performed and verified. Based on the results, the pre-heat treated steel head bolts developed in this study saved 7.3 % in production cost by eliminating the heat treatment process and the logistics process. Furthermore, the leak problem on the head bolt seat area in the A/C compressor was addressed significantly on the mass production assembly line.

• PNF and Movement
• /
• v.18 no.1
• /
• pp.45-53
• /
• 2020

Purpose: This study investigated the correlation between standing balance and head-forward posture in adolescents. Methods: The participants in this study were 15 female adolescents. We took photographs of the participants' craniovertebral angle with a digital camera to determine the degree of head-forward posture. Standing balance was evaluated using the 30-second Romberg test of BT4. The measurements were taken on a stable-support surface and on an unstable-support surface using a balance pad. The data measured in this study were analyzed using SPSS version 23.0, and the statistical significance level α was established as 0.05. Pearson correlation coefficient analysis was performed to identify the correlation between the degree of head-forward position of the participants and their balance ability. Results: When we measured 30 seconds of the Romberg test, we observed that, with their eyes open, the participants' head-forward posture and balance were not correlated. However, with their eyes closed, there was a strong correlation between the forward position of the head and the balance ability, which declined as the head position increased. Conclusion: Adolescents with severe head-forward posture exhibited problems with balance in posture control with closed eyes when visual information was not available. It can be inferred that an abnormality occurs in proprioceptor sensation due to their habitual head-forward posture. Education on correct posture and preventive activities should be recommended to improve the health of such adolescents and avoid possible future problems of physical deterioration.

• Journal of Audiology & Otology
• /
• v.25 no.1
• /
• pp.43-48
• /
• 2021

Background and Objectives: Conflicting mechanisms have been reported about spontaneous reversal of positional nystagmus during head-roll maneuver in patients with benign paroxysmal positional vertigo (BPPV). The objective of this study is to review the reports about the characteristics and possible mechanisms of reversing positional nystagmus and to present seven new cases. Subjects and Methods: Seven cases (5 males, 2 females; 4 left-sided, 3 right-sided) were recruited among 732 patients with BPPV seen outpatient clinic between 2009 and 2019. Diagnosis of lateral canal canalolithiasis was confirmed when transient geotropic nystagmus was documented during head-roll test. Reversing positional nystagmus was analyzed in each case and clinical characteristics of the patients were documented. Results: The age of patients was ranging between 30 to 64 years (46.44±10.91). Duration of symptoms was short (21.34±19.74). Six of them had a story of head trauma. Initial latency was short. First, intense geotropic nystagmus was observed following provocative head-roll position on the affected side. There was short "silent phase". Then, a longer second-phase of reversed nystagmus was noted. Total duration of nystagmus was 78.40±6.82 seconds. Maximal slow phase velocity was 24.05±6.34 deg/sec. All patients were cured with barbeque maneuver. Conclusions: Ipsilateral reversing positional nystagmus during head-roll maneuver is due to lateral canal canalolithiasis. Mechanism is likely to be due to endolymphatic double flow. Bilateral cases may be due to simultaneous co-existence of canalolithiasis and cupulolithiasis. Longer recording of nystagmus is recommended not to miss the cases with spontaneous direction-changing positional nystagmus.

• Korean Journal of Audiology
• /
• v.25 no.1
• /
• pp.43-48
• /
• 2021

Background and Objectives: Conflicting mechanisms have been reported about spontaneous reversal of positional nystagmus during head-roll maneuver in patients with benign paroxysmal positional vertigo (BPPV). The objective of this study is to review the reports about the characteristics and possible mechanisms of reversing positional nystagmus and to present seven new cases. Subjects and Methods: Seven cases (5 males, 2 females; 4 left-sided, 3 right-sided) were recruited among 732 patients with BPPV seen outpatient clinic between 2009 and 2019. Diagnosis of lateral canal canalolithiasis was confirmed when transient geotropic nystagmus was documented during head-roll test. Reversing positional nystagmus was analyzed in each case and clinical characteristics of the patients were documented. Results: The age of patients was ranging between 30 to 64 years (46.44±10.91). Duration of symptoms was short (21.34±19.74). Six of them had a story of head trauma. Initial latency was short. First, intense geotropic nystagmus was observed following provocative head-roll position on the affected side. There was short "silent phase". Then, a longer second-phase of reversed nystagmus was noted. Total duration of nystagmus was 78.40±6.82 seconds. Maximal slow phase velocity was 24.05±6.34 deg/sec. All patients were cured with barbeque maneuver. Conclusions: Ipsilateral reversing positional nystagmus during head-roll maneuver is due to lateral canal canalolithiasis. Mechanism is likely to be due to endolymphatic double flow. Bilateral cases may be due to simultaneous co-existence of canalolithiasis and cupulolithiasis. Longer recording of nystagmus is recommended not to miss the cases with spontaneous direction-changing positional nystagmus.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.46 no.6
• /
• pp.1128-1141
• /
• 2022

Due to increased interest in safety in sports, leisure, industries, and daily life; the demand for products that protect the head is increasing. As a preparatory study for the development of head protection for head injury prevention, this study analyzed patents and utility models related to head protection products such as industrial safety helmets, vehicle helmets, and sports protection gear. For this study, 368 patents and utility models for head protection products searched through WipsOn were selected and analyzed by application year, function, application, protection area, main material, and subject. From the analytic results of this study, the quantitative and qualitative flow and characteristics of developing technology related to head protection products were identified. Through the trend of current technology, it provided data to seek the development direction in the future. The significance of this study is to secure objective data to establish a road map for creating new Intellectual Property for head protection products.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.626-628
• /
• 2001

고 기록 밀도의 HDD를 위해서는 HDD Media의 선 기록 밀도와 트랙 밀도를 높여야 한다. 선기록 밀도를 높이기 위해서는 HDD Write Head의 Field Gradient가 커야하고, 트랙 밀도를 높이기 위해서는 Write Head의 Aspect Ratio가 작아져야 한다. 본 연구에서는 3차원 유한 요소법을 이용하여 Write Head의 재료의 자기적 성질과 형상에 따른 고 기록 밀도용 Pole Tip Write Head를 설계하였다.

• Proceedings of the KSLP Conference
• /
• 2013.03a
• /
• pp.20-20
• /
• 2013

• Proceedings of the KSLP Conference
• /
• 2011.03a
• /
• pp.14-14
• /
• 2011

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 2010.03a
• /
• pp.44-44
• /
• 2010

• Journal of the Korean Magnetics Society
• /
• v.6 no.1
• /
• pp.7-14
• /
• 1996

According to demands of high density and wide band magnetic recording systems, a composite MIG head was developed. This head has the sufficient performance for use of a SD VCR : its characteristics are a good recoding performance, a low rubbing noise, a good frequency dependence of efficiency, and a good compatibility with ME tape. In a SD VCR system, the C/N value of a composite MIG head at 20.92MHz was 51 dB.